Design and Construction of the IRT: Civil Engineering (Scott)
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Design and Construction of the IRT: Civil Engineering (Scott) |
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Design and Construction of the IRT: Civil Engineering Charles Scott
Historic American Engineering Record The records in HAER were created for the U.S. Government and are considered to be in the public domain. It is understood that access to this material rests on the condition that should any of it be used in any form or by any means, the author of such material and the Historic American Engineering Record of the Heritage Conservation and Recreation Service at all times be given proper credit. For information on HAER, visit Built In America: Historic American Buildings Survey and the Historic American Engineering Record, 1933-Present, Library of Congress American Memory Project. Part I[page 208] The October 24, 1885, Engineering News and Contract Journal announced:
William Barclay Parsons, future Chief Engineer of the Rapid Transit Commission and one of the men most responsible for New York's first subway, the IRT, had returned to the city in which he had acquired his engineering education. William Barclay Parsons graduated from Columbia College in 1879. The following fall he entered the Columbia School of Mines, from which he received a degree in civil engineering in 1882. Shortly thereafter, he joined the Erie Railroad, where he was assigned to the division engineer's office at Port Jervis, New York. From Port Jervis, Parsons moved to Rochester, where he supervised the reconstruction of the Erie's "Rochester Division." His experiences on the Erie provided him with the material for his two textbooks on railway maintenance of way, Turnouts (1883), and Track (1884). At the urging of his brother-in-law, civil engineer S. A. Reed, he returned to New York City to establish himself as a consulting engineer. Once in New York, Parsons devoted a portion of his time to a new field of civil engineering, subway construction. He served on the engineering staff of two companies, the New York District Company and the City Railway Company, which sought, unsuccessfully, to construct underground rapid transit railways. While neither the District nor the City Company succeeded in constructing its underground road, Parsons gained valuable experience and a thorough knowledge of Manhattan's geography and transit needs.2 In October of 1886 Parsons left New York to serve as Chief Engineer for the Fort Worth and Rio Grande Railroad. He did, however, retain his affiliation with the District Railway Company.3 In 1887 he became the Chief Engineer and General Manager of the Denver Railroad and Land and Coal Company.4 Upon the completion of these railway projects and a number of water-works ventures in Mississippi, Parsons returned to New York in 189l.5 His reputation as a railroad engineer, his experience with the City and District Companies, and his past association with iron-maker and New York Mayor Abram Hewitt,6 made Parsons a logical choice for appointment in 1891 when the New York City Board of Rapid Transit Railroad Commissioners chose an engineering staff to design the specifications for an underground railway. He was made assistant to the Chief Engineer, William Worlen, a past president of the A.S.C.E. When, however, private capital neglected to bid seriously on the proposed franchise the plan was abandoned and both Parsons and his chief, the sole professional experts [page 209] on the Commission, were dismissed. In 1894, a second attempt to finance an underground rapid transit railway was made by a reconstituted Board of Rapid Transit Commissioners. This time, Parsons was appointed Chief Engineer. He modified the 1891 plans, proposed a four track, electrically powered underground railroad located close to the street surface, and spent the latter half of 1894 defending the feasibility of the proposal.7 He made frequent appearances before a special commission empowered by the Supreme Court to investigate the practicability and desirability of the underground railway. Confident and articulate in defending the proposed subway, he rapidly answered the technical questions addressed to him during the commission's public hearing, and impressed even those opposed to the line's construction.8 Negative legal decisions, economic uncertainty, and the outbreak of the Spanish American War, however, impeded the line's construction. Parsons spent 1898 and 1899 surveying rail lines in China.9 In 1899, when approval was received for the subway to be built, he returned to New York to supervise its construction.10 At the end of 1904, with the majority of Contract One construction completed and a large portion of the subway in operation, William Parsons resigned as Chief Engineer of the Board of Rapid Transit Railroad Commissioners.11 Appointed to the Isthmian Canal Commission, he traveled to Panama as a member of the Committee of Engineers and urged the construction of a sea level canal rather the lock type subsequently constructed. Upon his return to the United States in 1905, he established a consulting engineering firm with Eugene Klapp, a former division engineer of the Board of Rapid Transit. The Steinway Tunnel, a railroad tunnel beneath the East River, connecting mid-Manhattan, (34th Street) to Queens, financed by August Belmont, was the firm's first project. Saint-John Clarke, another former Board of Rapid Transit division engineer, assisted Parsons in supervising the tunnels' construction. In 1905, Parsons accepted the position of Chief Engineer of the Cape Cod Canal, whose design and construction he supervised over the next nine years. Other projects undertaken by Parsons after constructing the New York subway included hydroelectric plants throughout the eastern United States; urban and interurban transit studies for San Francisco, Detroit, Baltimore, Chicago, Philadelphia and other American cities; and a bridge, dock, and land reclamation study in Cuba. Parsons also found the time to write American Engineers in France, a chronicle of his experiences as a military engineer during World War I, Robert Fulton and the Submarine, and a multi-volume Engineers and Engineering of the Renaissance. Parsons died on May 9, 1932.12 As a civil engineer, William Parsons numbered among the elite of the profession. Early in the 19th century, the precise functions of the civil engineering profession were undefined, and civil engineers were often craftsmen/entrepreneurs rather than highly specialized and professionally-trained experts. The engineers of the early canal and railroad [page 210] construction projects were practically trained men whose responsibilities "involved propriety and managerial functions in addition to the strictly technical."13 The rapid growth in the number of engineers during the second half of the 1800s forced a redefinition of the traditional relationship between the engineer and society. Founded in 1852, the American Society of Civil Engineers had become by the 1870s the recognized professional engineering organization. By the turn of the century, with the aid of the A. S. C. E., the modern engineer had emerged. The civil engineer of 1900 was ideally well educated, cultured, and imbued with a sense of social responsibility. Whether he supervised the building of railroads, the tunneling of sewers, or the construction of aqueducts, his jobs were large, socially significant, and often publicly financed projects.14 New York's underground rapid transit railroad was just such a project. Other means of transportation existed in the city surface and elevated lines, but they had originated as short stretches of track, expanding and consolidating to form the systems evident in 1900.15 The subway system was conceived on a large scale from the start. It was to serve the entire length of Manhattan and parts of the Bronx, connecting not one avenue to the next, but linking distant communities. The social repercussions of such an undertaking were likely to be proportional to the enormity of the project itself.16 Parsons, associated with this municipally sponsored project from 1891 until his resignation in 1904, keenly felt the social implications of his role as Chief Engineer. In March of 1905, one half year after completion of the first part of the IRT, he delivered an address at Purdue University entitled "Rapid Transit in Great Cities," which reviewed several of the most recent and significant transit projects, including New York's first subway. He argued that America's myth of the practical man, the enthusiastic individual battling the odds, was outdated. The socially significant engineering works of the day, he said, required "something more in the way of a foundation than an enthusiastic dream; there is needed from the beginning the cold analytical methods of a trained and educated mind."17 Parsons envisaged an educated professional engineer: "The engineer of today, and more especially of the future, will be concerned not only with calculations, but will also have to study men and their needs, questions of industrial demand, the law of finance, and much in regard to legislation. His it will be to conceive, to plan, to design, to execute, and then to manage."18 The education of the engineer was to equip him, in short, to do it all. The engineer was, unlike other workers, to manage the fruits of his labor. Parsons conception of the engineer, demanding a mastery of numerous social sciences, underscores the emerging sense of the delicate yet vital relationship between engineering and broad social problems. The stress was on the project and on its designer/manager. The engineer, rather than the financier or workman, was society's ultimate benefactor. [page 211] The engineer was the advocate of efficiency, and for this reason Parsons deplored the wasteful competition of the numerous private companies undermining the success of rapid transit in London. In Paris, on the other hand, he saw "monopoly working smoothly for its own advantage and the public benefit..."19 This social awareness, a vague commitment to the public good combined with a sense of leadership and responsibility, was shared by many of Parsons professional contemporaries.20 Benjamin M. Harrod, in his presidential address to the American Society of Civil Engineers, predicted that civil engineers would be the leaders in the state of the future. H. G. Prout, editor of Railroad Gazette, told the 1899 graduating class of Stevens Institute that engineers might serve by virtue of their professional training, as correctors of human depravity as well as designers of structures. George S. Morrison, in 1903, disparaged "Yankee ingenuity" as a progressive force. His view of the scientific training and analytical ability demanded of engineers tailed nicely with Parsons'; Charles F. Scott, a prominent electrical engineer, wrote in 1904 that the young engineer was entering the profession "at a time when social and industrial affairs are in the middle of great changes, and at a time when the work of the engineer is most fundamentally and intimately related to these great movement."21 These prominent engineers did not, in their public addresses, tie their sense of social obligation concretely to specific engineering works. They pictured themselves as the planners, managers, leaders of society, with visions and duties extending beyond individual projects.22 Parsons' work on the New York rapid transit subway allowed him to translate his more general belief into practice. Three principle factors guided and shaped the work of the Board of Rapid Transit Railroad Commissioners: a particular vision of rapid transit; the acquisition of a large, well-trained engineering staff; and the organization of the engineers into two distinct groups, the staff of the Commission and the staff of the Rapid Transit Subway Construction Company. High speeds along an independent right of way covering great distances were essential to the Board's view of rapid transit. All planning and implementation of the system would have to be done with these objective in mind.23 Parsons wrote in 1905 that an engineer "...is more valuable... in proportion as he can successfully master all the elements of his problems."24 The work was to be approached broadly, because a narrow frame of reference would result in a product ill-suited to its intended use. Parsons' 1894 report for the Board, Rapid Transit in Foreign Cities, exemplified this broad outlook. It analyzed the different transit systems within their own physical and social contexts, evaluating their applicability to other cities with a consideration of the different needs and aims in each individual situation.25 Parsons did not examine street railway systems, only tunnel and elevated roads providing rapid transit on exclusive rights of way. Nor did he confine himself to the examination of a particular type of motive power. The purpose of the Board, [page 212] as Parsons saw it, was not to tunnel a road and run electric cars through it. Its purpose was to establish a system of rapid transit for a significant urban area, with the particular needs of New York City in mind. The credentials of the engineering staffs of the Board and the IRT met Parsons' high standards. Parsons' Deputy Chief Engineer, George S. Rice, served as Chief Engineer for the Boston Rapid Transit Commission between 1891 and 1892, and made extensive investigation and reports. Parsons and Rice, after years of study of rapid transit systems in intimate relation to the specific urban environment, were well suited to direct New York City's rapid transit project in accordance with the Board of Rapid Transit's broadly conceived plan. Building the subway rapidly and economically required that construction be started at as many places as possible. To ensure that the materials used complied with the contract specifications, and supervising the diverse and often geographically scattered work sites required a large and effectively placed staff of engineers and inspectors. "For the convenience of superintending the construction,"26 five engineering divisions were established. Each engineering division was supervised by a Division Engineer. One division, the sewer division, was responsible for supervising the contractors employed to excavate, relocate, and reconstruct all sewers and drains to be disrupted by the subway. The other four divisions corresponded to the four geographical sections listed in the construction contract. A Deputy Chief Engineer was appointed to assist in directing the work of the large staff of draftsmen and inspectors. A Bureau of Inspection was established responsible for to test and inspect materials at the point of production. Dozens of inspectors and assistant engineers monitored the actual construction.27 Final authority for the design and construction of the subway rested with the engineers of the Board of Rapid Transit.28 The contractor and sub-contractors also employed an engineering staff. The contractor appointed a Chief Engineer and General Manager, the latter to "lay out a scheme for the operation of the road and the acquisition of the necessary equipment."29 The contractor also employed an electrical engineer, a mechanical engineer, and a car designer, "all particularly eminent in their several specialties."30 Because of the size of the project, the contractor divided the route into fifteen sections and enlisted subcontractors to perform the actual construction. Each of the subcontractors employed a civil engineer responsible for directing the work on his particular section and implementing the directives of the engineers of the Board of Rapid Transit. The composition of the Commission's engineering staff was rich in technical school graduates. Parsons' belief in the necessity of a broad engineering education was of course not the only factor bearing on staff selection; the large percentage of graduates may simply have reflected the greater number of men preparing for engineering careers in such schools.31 But, Parsons' supervision of personnel selection doubtless contributed to the highly professional character of his staff. Like him, 27 of his 117 original engineers, were [page 213] Columbia graduates. George S. Rice, the Deputy Chief Engineer, was a Harvard graduate. Among the division engineers, Beverly R. Value represented Columbia; William A. Aiken held a B.A. from Loyola and a degree in civil engineering from Rensselaer; and Albert Carr was a Yale graduate. Of all division engineers and assistant engineers, 100 of 118 were college graduates. Among the rodmen and axmen of the surveying staff, 73 and 37 respectively were graduates of a college.32 Positions below the level of Division Engineer were filled by competitive Civil Service examination, but many of those holding these positions were also technically trained men. Both the popular and the engineering press found this information worth comment.33 The credentials and backgrounds of engineers attracted to the consulting positions and to the service of the Rapid Transit Subway Construction Company, were no less impressive. Louis B. Duncan, of Duncan and Hutchinson, the electrical consultants to the Commission, held a doctorate from John Hopkins University. During his tenure as consultant to the subway project he was appointed chairman of the Electrical Engineering Department at Massachusetts Institute of Technology.34 In supervisory positions on the Rapid Transit Construction Company staff, S. L. F. Deyo, the Chief Engineer, and John Van Vleck, designer of the boiler and operating plant of the subway power house, were both Union College graduates. Lewis B. Stillwell, the electrical engineer, held an engineering degree from Lehigh, and George Gibbs was a Stevens Institute graduate.35 While the construction of the New York rapid transit subway was a major engineering project, it was also a business venture. The end product was to be a commercially profitable rapid transit railroad. August Belmont, financing the venture, took an active interest in the recruitment of the engineering staff of his construction and operating companies.36 One of the earliest recruits was E. P. Bryan, superintendent of equipment and later general manager of the Interborough Rapid Transit Company. Through without an engineering degree, he had vast railroad experience, beginning as a telegraph operator and advancing to General Manager of the Terminal Railroad Association of St. Louis. His most noteworthy achievement was the supervision of the Union Station in that city. He brought managerial and business expertise to the Interborough Company, qualities useful to financier Belmont.37 Bryan's early arrival may also have enabled him to advise Belmont in the selection of other railroad engineers. Solomon L. F. Deyo, Chief Engineer of the Rapid Transit Subway Construction Company, also came to the Interborough Rapid Transit Company from steam railroading. After graduating from Union College, his railroad work was interrupted only briefly when he served as superintendent of the American Metaline Company, a manufacturer of dry lubricants. He then joined the staff of the Buffalo and Geneva Railroad, and later worked for the New York, New Haven, and Hartford Railroad.38 Among the electrical and signaling engineers, Lewis B. Stillwell and George Gibbs stand out as significant designers and innovators. Stillwell's background and experience was remarkably suited to his work on the subway. He joined the Westinghouse Electric and Manufacturing [page 214] Company staff in the 1880s and by 1895 was an assistant manager. He joined with engineer and scientist O. B. Shallenburger and William Stanley in research on alternating current technology. The extensive hydroelectric project at Niagara Falls in the 1890s was one of the first great ventures in alternating current transmission,39 and when Westinghouse took the contract for the electrical equipment, Stillwell took charge of production and installation. In 1895, he left Westinghouse to become electrical director of the Niagara Falls Power Company and the Contract Construction Company. The Niagara project publicized the possibilities of alternating current transmission. While at Niagara, Stillwell took on consulting assignments at other power and railway installations. Most important of these, with reference to his later work on the subway, was his job as electrical consultant to the Manhattan Railway Company during the electrification of its elevated lines between 1899 and 1902.40 His experience on this project proved of great significance in the selection and design of an electrical system for the subway as the subsequent electrical engineering report will show. George Gibbs' first job after his graduation from Stevens Institute in 1882 was at Thomas Edison's Menlo Park laboratory. He was involved in the early operation of Edison's first central electrical generating station at Pearl Street in New York. In 1895, he worked for the Chicago, Milwaukee, and Saint Paul Railway as head of the testing department, performing chemical and physical analyses of materials for railroad car construction. His work with this road, which included designing and occasionally patenting steam heating and electric lighting systems for railroad cars and improved signaling systems, brought him to the attention of George Westinghouse. Westinghouse was just entering the direct current railway field and Gibbs became his representative in Europe. In this capacity, Gibbs took charge of the electrification of the Mersey Tunnel in Liverpool, England, and was a consultant to the Paris underground railroad. His consulting work for the New York subway, involving supervision of rolling stock, tracks, switching, signaling and repair shops, drew on this rich experience. In New York, Gibbs continued his career as inventor and innovator, designing a trip for the automatic safety brake for the subway, and latch mechanisms for the sliding doors adopted for the rolling stock. With the cooperation of both the Interborough Company and the Pennsylvania Railroad, Gibbs designed the first all steel passenger cars used in heavy railroading. He introduced them into subway service, and the design was soon adopted by the Pennsylvania and the Long Island Railroad Companies, and their use quickly became standard railway practice.41 The most prominent engineers on the staffs of the Board of Rapid Transit Commissioners and the Rapid Transit Construction Company had experience primarily with steam railroads on electrically operated elevated, tunnel, or trunk lines. None of those considered above had [page 215] experience in electric street railway work. The experience of men in the heavy, high speed lines offered more to the projects than could those experienced with smaller, slower surface lines. The common thread which wove their efforts together was the desire of the Board, and especially its Chief Engineer, to provide New York City with a transit system characterized by a rapidity and convenience unknown in other major cities. The "Contract One" New York subway was to be the model for, and basis of, a system of underground rapid transit whose periodic expansion could serve the City's constantly growing population. Part II[page 219] The idea of underground railway transit had fascinated civil engineers as early as the 1850's. The first passenger carrying underground railway, the Metropolitan Railway, was built in London, 1860.1 The first section of the Metropolitan was completed in January, 1863.2 The Metropolitan and the later Metropolitan District Railway operated beneath public streets and private property. The two roads traveled through shallow open cuts and in brick arch tunnels. A special construction, "masonry side walls and iron cross girders with brick jack arches turned between them," was used wherever it was necessary to reduce the height of the tunnel.3 Only a small portion of the railway, was built by tunneling "cut and cover" construction, in which the railway structure is built in an open excavation, with the surface later restored to its original condition, was used almost exclusively in constructing the Metropolitan and Metropolitan District Railway.4 Steam locomotives propelled the trains on both lines, and no mechanical system of ventilation was used in the tunnel portions of the railway. To compensate for the lack of adequate ventilation, "condensing" type steam locomotives, burning only sulfur free coke, were used.5 The early technical and financial success of London's underground railway spawned a multitude of proposals for railroad transit beneath the streets of Manhattan. The American proposals were little more than imitations of the London Metropolitan Railway, a masonry arch tunnel built at a depth of between twenty-five and thirty-five feet below street.6 As these first schemes were never realized, engineers suggested other types of underground transit design. The two most common of these alternative designs were the deep tube tunnel and the close to the surface or "Arcade" rail road. During the years between 1864 and 1896 the feasibility of each of these types of underground railroads was continually debated as each new underground rail road plan was proposed and then abandoned. In 1864, H. B. Willson proposed the construction of a five-mile long railroad, partly in tunnel and partly over ground, running between the Battery, on the southern tip of Manhattan, and an unspecified location near Central Park. A major portion of the double track, steam powered railroad. was to be constructed in a tunnel beneath Broadway. Willson proposed constructing the tunnel under Broadway, "there being found, on careful examination, no engineering difficulties of any moment in the way."7 The "Metropolitan" or "Underground Railroad" as Mr. Willson labeled his proposed railroad, was to provide local and express service. Trains, operated at a speed of twenty to twenty five miles per hour, were expected to cover the five miles between the southern terminus at Bowling Green and the northern station at Central Park in twelve minutes. Willson believed that railroad "when fully completed will be regarded as a work in point of utility and importance not inferior to the Croton Aqueduct,"8 but it was never constructed. [page 220] Refined versions of the Willson plan were periodically offered. The 1856 version of the Underground proposed to run beneath Fifth Avenue and 59th Street. Fifth Avenue was chosen because, unlike the other north-south avenues, it did not have a large number of water and sewer pipes buried beneath it.9 Civil engineers were enlisted to design the structure and the specific steps to be taken to construct the line. A. P. Robinson served as chief engineer for New York's "Metropolitan Railroad."10 The design advanced by Robinson called for a brick arch tunnel whose crown was to be approximately eight feet below the street and thus well beneath the water pipes and sewers. The tunnel was to be twenty-five and one-half feet wide and sixteen feet high at the center of the arch. The tracks were to be twenty-four feet from the street. Ventilation was through pipes running between the tunnel and the street. Drainage presented "no particular difficulties".11 Passengers were to ride in cars nine feet wide and forty feet long at a speed of twenty miles per hour between stations located at intervals of one half mile. Each car was to be capable of transporting eighty passengers. The sponsors of New York's Metropolitan Railroad estimated that three years would be needed to complete the project. Work was to commence at several points simultaneously to expedite the construction of the road.12 The Chief Engineer of the Croton Aqueduct, W.S. Craven, vigorously objected to any excavation necessitating the relocation and reconstruction of Croton water mains. He was certain the excavations would sever sewers and interrupt water service.13 Countering Craven, the sponsors of the Underground argued that the open methods to be used in constructing their line had been proven safe in constructing the London Underground railway, which ran through streets more heavily laden with fragile pipes than any street in New York. In constructing the railroad, "not a single experiment is proposed or to be attempted," concluded the Underground's directors.14 Engineer Robinson, however did admit that some problems would be encountered in building the railroad. Canal Street was "the real engineering difficulty."15 In crossing Canal Street, the railroad would bisect the sewer outlet to the North (Hudson) River. Robinson proposed building new sewers that would recognize the Underground Railroad as the dividing line between the east and west side drainage systems. The construction of the Underground Railroad would require that the sewers be rebuilt so that henceforth all sewers east of the railroad would drain into the East River and those sewers on the west side of the line would flow into the North (Hudson) River.16 The fear of a massive disruption of street traffic during the construction of an underground railroad was a powerful objection frequently used against the proposed line. To minimize the inevitable disruption of street traffic, Robinson suggested that the tunnel be constructed in four separate stages. First, a trench would be dug and sheet piling erected to hold back the earthen walls. In this narrow trench the foundation and one sidewall would be constructed. Upon completion of one sidewall, the second wall would be constructed in an [page 221] identical manner on the opposite side of the street. Once both sidewalls were in place and covered with earth so that traffic could again travel above them, the middle of the street could be excavated and the arch between the sidewalls built while traffic was detoured to the sides of the street. With the arch completed, the street could be backfilled and repaved while the construction of the invert or bottom of the tunnel proceeded without interruption. Where this method of construction proved impractical, wooden bridges were to be built covering the entire excavation and allowing traffic to travel as usual while the excavation of the entire street took place beneath.17 The Central Underground Railway made the second attempt to construct an underground railroad in 1868. The Central proposed constructing a steam powered railroad running beneath Broadway from City Hall north to Astor Place and then up Fourth Avenue to Union Square. From Union Square the line was to travel beneath Madison Avenue as far as 120th Street.18 To "inspire the public with confidence in the success of the undertaking,"19 the directors of the Central Underground Railway relied heavily upon the expertise of British underground railroad engineers. Two of the directors, George Griswold and William Duncan, toured London's Metropolitan Railway, consulted with the engineers of the line, and contracted with the Metropolitan to import an engineering staff to direct the construction in New York.20 In 1869, the Central Underground reported that the examinations conducted by their engineers had removed "every obstacle that had been supposed to be in the way." With the questions of grades, lighting, tunneling and ventilation solved, construction could begin as early as February, 1870. Ventilation was no longer to be a problem as the Central intended to use a rather mysterious, "new motive power, which the engineers recommend for use in propelling the trains, dispensing with steam and smoke and much of the noise caused by running locomotives."21 To expedite construction, the railroad was to be built by a number of contractors, each undertaking a half-mile section simultaneously. Five thousand men were to be employed so that the work could be pushed forward by day and at night. Disruption of street traffic was to be kept at a minimum, "the earth being drawn out on over a thousand carts during the night while the streets are unobstructed."22 While the proposals of the Metropolitan Underground Railroad and the Central Underground Railway were looked upon favorably for their promise to substitute "steam power for horse power,"23 in their conveyance of passengers, their reliance upon British designs and construction methods prompted a measure of criticism. The New York Times cautioned that:
[page 222] A third and significantly different underground railroad proposal was advanced by the New York Arcade Railroad. The Arcade Railroad differed from the New York Metropolitan and Central Underground Railroad primarily in the type of structure to be built and in the depth of its location. The Arcade Railroad Company proposed a shallow excavation of Broadway to a depth of fifteen feet. At this depth a subterranean street would be built within the curb lines of the street above. Upon this subterranean street a four-track steam powered railway was to be constructed. The railroad was to be bordered by sidewalks and stores occupying the basements and vaults of adjacent buildings.25 By 1870, the Arcade Railroad boasted that its revised plans had "the unqualified and unanimous support of Broadway property holders who have taken the time to study it."26 To reduce the noise and vibrations, the revised plans of the Arcade Company called for the tracks to rest on a "longitudinal section of rubber or other elastic substance." To allow street traffic to move smoothly, the Arcade Company planned to use movable wooden bridges to fully cover the excavation.27 The first actual construction of an underground railroad in New York began in 1869. Alfred E. Beach, the editor of Scientific American, proposed a pneumatically propelled railroad running beneath Broadway. In 1867, Beach demonstrated the feasibility of his concept of pneumatic transit, building a short wooden tube in which a railroad car carrying twelve passengers was propelled by a large fan located at one end of the tube. In 1869, Beach began excavating his tunnel from the basement of a building on Warren Street near Broadway. The Beach tunnel ran east from Warren Street to Broadway, where it turned at a 90" angle and ran for one block beneath Broadway. Since Beach did not have a franchise to excavate beneath Broadway, the construction of his tunnel was carried out clandestinely for 58 nights. At the Warren Street end of the 312 foot long, 8 foot diameter tunnel, a large chamber housed a small station and a large blower for propelling the single passenger car. The car was circularly shaped and only slightly smaller than the diameter of the tunnel. The fan generated an air current that forced the car forward. A vacuum, created by reversing the fan so that suction discharged the air through an exhaust vent, permitted the car to be returned after it had been blown forward.28 Beach opened his underground railroad to the public in February of 1870 and continued to operate it for almost a year, until pressure from some Tammany politicians forced its abandonment. The method used by Beach to construct his tunnel was almost as unique as his pneumatic railroad. Beach was the first American to use a hydraulically powered "shield" in driving his tunnel. The shield used by Beach permitted the tunnel to be driven without disturbing the surface above the tunnel. Eight iron shelves with sharpened edges formed a full circle the width of the tunnel. The material inside the shield was removed and a permanent cast iron or brick lining installed. While Beach used a relatively advanced method to drive his tunnel, his methods of aligning its course was considerably less advanced. Each night, Beach aligned his tunnel by driving a jointed rod up through the roof of the tunnel and through the street where he could view it.29 [page 223] In 1873, at the urging of prominent civil engineer Octave Chanute, the American Society of Civil Engineers, established the "Committee on Rapid Transit and Terminal Freight Facilities." The committee investigated hundreds of designs for surface, elevated, and sub-surface passenger and freight railways.30 Their report, issued in 1875, recommended elevated rather than underground passenger railways for Manhattan. Among their objections to underground railways were:
One engineer, Charles H. Fisher, argued that the topography of Manhattan itself prohibited the construction of an underground railway. Concluded Mr. Fisher, "It is well known to those familiar with the topography of New York, that it is not at all suited to underground projects owing mainly to the low depression which crosses the City from North to East Rivers, in which there was formerly a canal."32 (A reference to Canal Street). Despite the ASCE's endorsement of elevated rather than underground railways, civil engineers continued to offer designs for underground transit systems. The Harlem River Tunnel Company, which had proposed building railroad freight tunnels beneath Manhattan, and the remnant of the original Underground Railroad of 1864, joined, in 1880, to form the.New York Underground Railway. The New York Underground Railroad proposed building two double track tunnels between Battery Park and Central Park similar in design to those suggested by the Underground Railroad between 1864 and l866.33 [page 224] The Broadway Underground Railroad, the successor to the Arcade Railroad Company, also sought to build their railroad using a modified version of an older design. In 1884 the Broadway Company obtained a charter to excavate Broadway to a depth of fifteen feet and construct a passenger transit railroad in the manner of the original Arcade Railroad scheme. The charter, however, limited the width of the excavation to thirty-five feet, insufficient for a four-track standard gauge railroad. To operate within the limits of their franchise, the Broadway Company proposed constructing not a two-track railroad, but rather, four narrow gauge tracks. Unlike the original Arcade Railroad, the Broadway proposed using either electricity or compressed air to operate their locomotives.34 A year later the Broadway Company had committed themselves to using electric engines, but had moved no closer to constructing their line than any their predecessors.35 In 1886, the New York District Railway obtained the right to construct a passenger railway beneath Broadway. The District Company proposed a build a line from Bowling Green at the southern tip of Manhattan north, beneath Broadway, to Madison Square. At Madison Square a west-side line was to branch off, run beneath Broadway and terminate at Eighth Avenue and 59th Street, while the main line continued up the east side beneath Madison Avenue, under the Harlem River and into the Bronx. The line was to be built with four tracks, so that both express and local service could be provided. The engineers of the District Company, with Parsons at their head, proposed to construct the line entirely beneath public streets and to use the existing curb lines. Water, gas and steam pipes, pneumatic tubes, electric cables, and sewers were all to be relocated in galleries constructed parallel to and adjacent with the route of the subway. The line was to be constructed by open excavation in small sections so as not to disrupt a large volume of surface traffic.36 Plans called for the excavation of the line to be 16 feet deep and 35 feet wide, with an additional four and one-half feet on each side of the railway to be occupied by the pipe galleries. A foundation of concrete two feet thick, coated with a thick layer of "Trinidad" asphalt, was to be laid along the entire length and width of the line. The external walls, the partitions separating, the railway from the pipe galleries, the track, and the columns supporting the roof girders were to be built upon this foundation. The exterior walls were to be of brick masonry and the center columns were to be wrought iron, spaced four feet apart resting upon cut granite footing stones. Iron girders were to be placed transversely across the columns and a roof constructed from steel plates would rest across the girders. Upon these plates was to be placed a full two inches of asphalt waterproofing and a six-inch layer of concrete. The street pavement was to be relaid directly above this steel, asphalt, and concrete roof. A unique feature of the District Company design was the proposal to place between the iron columns a longitudinal partition of "steel wires interlaced with flax or vegetable fiber and oil compound, the whole pressed into a solid panel by hydraulic pressure." The "Ferflax" was expected to significantly deaden the noise produced by the electrically powered trains that were to utilize the tunnel. It was estimated that with the methods of construction to be used the cost per mile would not exceed three million dollars per mile.37 [page 225] The District Company, however, never obtained the funds necessary to begin construction. The high cost of construction was not the only criteria used to question the viability of underground rapid transit. The Sanitary Engineer argued that a system of rapid transit would provide riders with a comfortable, rapid and inexpensive ride that did not annoy residents adjacent to the route to travel. In looking at existing modes of urban transit, the Sanitary Engineer concluded:
However, underground railway transit was seen as even less of a viable alternative than the surface or elevated lines. Even with the prospect of an electrically propelled underground railroad, the Sanitary Engineer concluded:
[page 226] The City Railway Company offered New York another variant of underground rapid transit, one that promised to improve at the very least, the health and safety of those living above the route of the proposed railroad. The City Company proposed constructing an underground railroad through the middle of blocks, beneath private property. Once the four track line was constructed, new fireproof residential and office buildings would be constructed over the railway. Drawing upon the idea of the Arcade Company, the City Railway intended to construct their line as a shallow tunnel railroad with the track twelve feet below the surface of the street. Electricity was to provide the motive power for the line. The City Railway Company anticipated that building its four tracks line and restoring the surface with five story fireproof buildings would cost approximately $3,500,000 per mile.40 Less than one month after the City Railway proposed its novel form of underground transit, an underground railroad unlike any previously considered, a deep tunnel line, was proposed by a New York City construction contractor. The route of this deep tunnel railroad was also unlike any previously proposed. The line was to begin in the Bronx, cross into Manhattan and, buried deep beneath Central Park and Fifth Avenue, continue south to Washington Square. A Washington Square line was to proceed to City Hall Park where it would divide, one line turning west and crossing into Jersey City, New Jersey, where it could connect with the large terminals of large trunk railways, while the other branch continued south to the Battery. From the Battery the railroad line was to cross into Brooklyn and emerge as a surface road at Prospect Park, continuing above ground to a terminal at Coney Island.41 The tunnels were to be driven at a depth of 150 feet below the surface. Elevators were to transport passengers between the street and the tunnel stations. Asked why he had chosen to propose a deep tunnel rapid transit railway, contractor Clarke responded: "In order to avoid steep grades and to get a perfectly unbroken solid sub-stratum of rock in which to work. Furthermore, at that depth the concussions and jars from explosions in mining will be hardly perceptible at the surface and therefore unobjectionable."42 Clarke did not specify whether steam or electric locomotives would power his underground railroad. He did indicate that mechanical devices would be employed to assure that the tunnels were adequately ventilated.43 The deep tunnel proposed by Clarke was never constructed. His idea for a deep tunnel railway connecting Brooklyn and Manhattan with the major railroad terminals on the west side of the Hudson was, however, revised and subsequently championed by the Metropolitan Railway Company of New York in 1890. While American engineers were designing and proposing underground railways that were never built, European engineers were supervising the construction of subways that would provide the model for the IRT. Between 1884 and 1900, steam powered underground railways, electric underground rapid transit railways, and electrically powered elevated railways were [page 227] constructed in London, Liverpool, Glasgow, Paris, and Budapest.44 The City and South London Railway, begun in 1886, was a radical departure from previous London underground railway construction. Unlike the Metropolitan Railways, the City and South London was built as a deep tunnel. The three-and-a-half mile railway traveled in two cast-iron lined tubular tunnels located between forty and eighty feet beneath the streets of London. The deep tunnel construction necessitated the use of both stairways and elevators in the stations. The City and South London was unique for two reasons. First, the railway tunnels were driven using a circular shield in a manner similar to that used by Alfred Beach in driving his short tunnel beneath Broadway. Second, the City and South London, though designed as a cable railway, adopted electricity to propel its trains. Electric locomotives weighing between ten and a half and thirteen and a half tons pulled three-car trains up grades as steep as three percent at speeds of ten to twenty-five miles per hour.45 The completion of the City and South London Railway encouraged the construction of a number of similarly designed, electrically powered deep tunnel railways. The construction of the Waterloo and City Railway; Central London [now the Central Line]; Waterloo and Baker Street [Bakerloo Line]; and Charing Cross, Euston, And Hampstead [Northern Line Charing Cross Branch] added twenty-three and a half miles of deep tunnel railway to the London system.46 In 1886, after three years of construction, the Glasgow City and District Railway began operation. The three-mile line was built by an equal mixture of cut and cover, deep tunnel, and open construction. A steam powered road with a conventional brick arch tunnel, the Glasgow line was unique primarily because construction began at twenty-two different locations.47 The Glasgow Central, begun in 1888, used both brick arch and flat roof, iron girder construction. Because of the presence of large deposits of mud, clay and sand, the latter generally saturated with water,48 Glasgow's second underground railway was built close to the surface and almost exclusively by cut and cover. The presence of a large number of sewer pipes in the path of the railway, and the desire of the municipal officials that construction not disrupt traffic, necessitated some imaginative construction techniques. Sewers that intersected the subway were rebuilt to travel parallel streets, and water and gas pipes that crossed the route were replaced by a larger number of smaller diameter pipes, easily relocated above or long the side of the railway structure. Municipal officials limited the interruption of street traffic by permitting open excavation only between 12PM on Saturday and 5AM on Monday. Compliance with this regulation necessitated excavating, erecting, and restoring as large a section of railway structure as could be completed in the forty-one hours alloted by the municipal government. Glasgow's construction of a shallow tunnel by means of open excavation through difficult terrain, with a minimum of interruption to street traffic, demonstrated that the subway construction need not be prohibited for fear of disrupting the daily life of the city.49 [page 228] The Liverpool Elevated Railway, provided further and more dramatic testimony to the economy of electrical propulsion. Using the most advanced electrical generating equipment and burning an inexpensive grade of coal provided "financial results... even more satisfactory than in London...."50 In Paris, two steam railways provided local passenger service. The Chemin de Fer Ceinture, a twenty-mile long, two track belt railway, was built "according to the topography -- surface, open cut, tunnel and viaduct" construction being adopted. The Chemin de Fer de Sceaux, begun in 1891, while short in length (6,240 feet), provided a number of lessons in economical construction of sub-surface railway structures. Masonry arch tunnel, flat, iron girder tunnel, and open cut, comprised respectively 79, 15, and 5% of the line. Cut and cover construction was used extensively.51 In Paris, as in Glasgow, a unique method of construction was devised in order to reduce disruption of street traffic. Unlike Glasgow, where short sections of the whole structure were erected, the Chemin de Fer de Sceaux constructed longer sections of one half of the tunnel structure, leaving the other half of the street unexcavated. Where brick arch tunnel was used, one half of the street was excavated, the side wall and half of the arch constructed, and the street surface immediately restored. Shifting traffic to the completed side of the street, the other side was excavated, the remaining side wall built, and the arch completed. Once the arch was completed the core of earth left untouched beneath it was excavated using a railway constructed within the tunnel to haul it to a central hoisting structure. Where iron girders were used to build the structure, a similar procedure of erecting only one half the structure at time was also followed.52 The engineers responsible for supervising the construction of the Chemin de Fer de Sceaux reported that it was both "better and cheaper to: remove and introduce all material by train and not through the streets by wagon; use simple material, especially concrete; keep the rail level as close to the surface as possible, as the difficulties and expense increased with the depth."53 The Budapest underground railway, completed in 1896, was the first underground railway to substitute steel for iron and concrete for brick. The Budapest line, like the American "Arcade" and "District" Railway plans, ran through a shallow tunnel with masonry walls and a flat roof. Unlike its projected flat roof predecessors, the Budapest line used steel beams in the roof between which concrete arches were formed.54 While no American city had an underground railway comparable to those found in Europe, two American railroads, the Baltimore Belt and the Intramural of Chicago, contributed to the technical progress of rapid transit. The Baltimore Belt was constructed by the [page 229] Baltimore and Ohio Railroad to travel through Baltimore and cross the Patapsco River without using a car ferry. The critical portion of the seven mile, electrically powered railroad was the 8,350-foot section beneath Howard Street, one of Baltimore's most heavily trafficed streets. Cut and cover construction was used for 1,200 feet while almost 7,000 feet was tunneled. The tunnel was a brick arch structure whose crown ranged from ten to fifty feet below the street.55 The construction of the Baltimore Belt Railroad made a contribution to the future New York Rapid Transit Subway. It demonstrated that electric locomotives were capable of hauling heavy trains. The difficulty of constructing a tunnel railroad through water-laden sand, beneath a heavily traveled and built up street, necessitated that the contractor devise cautious methods of construction. The contractor who constructed the Baltimore Belt Railroad and gained this valuable experience was John B. McDonald. The Intramural Railway of Chicago, a short (2,800 feet) elevated railway, was the first United States railway to use electricity to propel "full trains run in a regular service." The success of the Intramural in 1894 prompted the Metropolitan West Side Railway of Chicago to choose electricity to propel their trains.56 The construction of the European undergrounds demonstrated that "... it had become possible to use, with comfort and cleanliness, the great sub-surface for transit purposes, a space hitherto considered of value only as a place to bury sewers, water and gas mains in haphazard and disordered confusion."57 European precedents encouraged American engineers to see that a practical and desirable alternative to the elevated railroad did exist. The introduction of electricity to propel the trains permitted the underground railway to be transformed into an underground rapid transit railway. Not only did electricity render ventilation less of a problem, but is also reduced the costs of operation. The introduction of steel and concrete provided engineers with an economical means of constructing large sub-surface railroad structures. With all the evidence available from foreign and domestic examples, two factors emerged to determine which of the many types of underground railways was most appropriate for New York: the cost of operation and the cost of construction. The operation of London's electrical underground railways, the Liverpool elevated, the Baltimore Belt Railroad, and the Intramural Railway of Chicago demonstrated that electricity offered the most economical means of propelling urban passenger trains. Electricity also permitted the trains to be operated in any type of tunnel, deep, intermediate, or shallow depth, where steam locomotives, because of the ventilation systems required, were restricted to the shallow or intermediate-depth tunnels, And since "the substitution of a motor other than an ordinary steam locomotive would at once remove "99.997% of the foul atmosphere from an ordinary railway tunnel,"58 the cost of ventilation systems could be avoided. [page 230] Glasgow demonstrated deep tunnels were eight times more expensive than open excavation. Paris confirmed that cut and cover construction of the shallow depth tunnel was the most economical. The general hypothesis that emerged from the European experiences was that the deeper the tunnel the more expensive it would be to construct.59 Additionally, the need for mechanical ventilation and elevators in the deep tunnel railway added to the cost of both construction and operation. The conclusion was that an electrically propelled railway built in a shallow or intermediate depth tunnel was both more economical to construct and operate. Private capital's inability to construct an underground railway in New York prompted more active municipal involvement in the rapid transit decision; in 1891 Mayor Hugh Grant appointed a new Rapid Transit Commission, the first in the city's history to have an engineering staff confined, as previously mentioned, by William Worthen and William Barclay Parsons. Charting the topography that the subway structure would encounter was the first step. Test borings were made along Broadway from South Ferry to 34th Street. The results of these tests were both unexpected and encouraging. The engineers learned that in general the presence of solid rock was was at a depth greater than generally believed; they encountered rock until 163 feet beneath Duane Street in lower Manhattan. The rock beneath Canal Street, however, was closer to the surface than had previously been believed. And the material encountered at Canal Street was not "muck and fine sand, but on the contrary," consisted "largely of good, coarse gravel and presents an excellent material for foundations."60 With the added knowledge devised from the borings, Worthen and Parsons proceeded to produce two differing proposals for a Broadway underground railway.61 Worthen offered a structure where all four tracks were located on a single level, while Parsons placed four tracks on a two-tiered, double track structure. Both Worthen and Parsons chose electricity as the motive power.62 Worthen envisioned a four track road built upon a concrete foundation. Iron columns would support a roof of wrought iron girders covered by iron plates. Upon this iron plate ceiling a layer of coal tar was to be placed to insure against water seepage and corrosion. The tunnel was to be built without interfering with the sub-surface sewers and pipes, because the roof of the structure was to be kept at least eight feet below the street.63 Parsons prefaced his proposal with a general description of the problems to be anticipated in constructing a subway beneath the streets of lower Manhattan and a discussion of the alternatives that existed to overcome the impediments. He found the major obstacle to the rapid and economical completion of an underground to be the maze of pipes, conduits, cables, and sewers beneath the streets. He concluded, "There are two general systems by which it seems possible to construct a railway under Broadway without interfering with the pipes and wires: a tunnel in solid rock reached by elevators, or a tunnel midway between the rock and surface, driven through the sand by a shield.64 [page 231] The result of the test borings had strengthened the argument against the construction of a deep tunnel railway, indicating that certain points in the downtown area rock was as deep as 160 feet below the surface of the street. To build a structurally sound tunnel, boring through solid rock would be required. With the surface of the rock at such varying depths, the construction of a deep tunnel railway would have to be at so great a depth, in some places 200 feet below the street, as to be excessively costly both to construct and to operate. Since a tunnel this deep would be inappropriate for a system designed for local as well as long distance travel, the alternative was to construct a tunnel through the deep layers of sand at a depth below the deepest pipe, or a tunnel that was located directly below the street, requiring relocation all pipes encountered during its construction. Parsons choose the latter alternative and explained the rationale for his choice:
Parsons concluded a tunnel that avoided interfering with sub-surface pipes would be uneconomical to construct. He recommended the railroad be constructed as close to the surface as possible and all pipes encountered during construction be relocated in such a manner as to avoid the subway and still allow access for repairs. Specifically, Parsons called for the construction of a two-tier roadway, each with two tracks and a center gallery for all pipes. Parsons' structure, like Worthen's, was to be built on a concrete foundation, have iron columns and cross girder, and be topped by an iron plate roof covered with a protective covering of asphalt.66 Both plans received considerable discussion in the popular press and among the engineering journals.67 Four consulting engineers were chosen to evaluate the two plans and decided Worthen's plan the least disruptive of street traffic. However, despite the popular discussion and the endorsement of the consulting engineers the plan went no further than the paper upon which it was drawn. [page 232] Passage of the Rapid Transit Act of 1894 inaugurated another attempt to construct a rapid transit subway. The 1894 Board of Rapid Transit Railroad Commissioners appointed William Barclay Parsons Chief Engineer, provisionally adopted the 1891 plan for a single level, four track subway beneath Broadway, and instructed Chief Engineer Parsons to investigate European rapid transit railways.68 Upon his return from Europe, Parsons expressed disagreement with the route chosen by the 1891 Rapid Transit Commission. He argued that since any construction beneath Broadway would provoke vigorous objections from adjacent property-owners, New Elm Street, an avenue parallel to and 100 feet east of Broadway, should be the route of the subway between City Hall and Astor Place.69 The Board of Rapid Transit Railroad Commissioners appointed a Board of Experts to evaluate Parsons' proposal. The Board of Experts consisted of four civil engineers; Octave Chanute, Thomas C. Clarke, William N. Burr, and Charles Sooysmith; and former Mayor Abram Hewitt. The five advisers endorsed Parsons' objections to the 1891 route, approved his altered design and verified the accuracy of his estimates of the cost of construction.70 The Board of Rapid Transit Railroad Commissioners, however, rejected the substitution of Elm for Broadway and accepted with minor modifications the 1891 plan of construction.71 On May 22, 1896, the New York Supreme Court denied the Board of Rapid Transit the authority to construct the subway along the Broadway route proposed in 1891. Having been denied the right to construct a rapid transit subway beneath Broadway, the Commission came round to the views set for by Parsons and the Board of Engineering Experts. A resolution passed by the Commission shortly after the Supreme Court decision directed the Chief Engineer to:
Within four months Parsons returned with a plan containing the modifications in compliance with the Court's objections to the 1891 plan. Parsons estimated that sufficient savings could be made if the portion between the Battery and City Hall Park were eliminated. The southern section of the line was placed beneath Elm Street, and the junction between the east and west side lines was moved from 14th Street to 42nd Street.73 As part of his relocation report, Parsons conducted test borings along Elm Street. The borings indicated that to the depth for which the excavation for the railway will be made, there was "no material found which would slide or give difficulty in handling."74 Rock at a level interfering with the subway structure was first encountered at 12th Street and continued north. It was during the Elm Street borings that tests for standing or ground water were first made. The tests revealed the ground water was found "about one foot above the level of the mean high tide."75 Parsons found this information encouraging since it indicated that with the exception of the line between Leonard and Grand Streets, a distance of 1,600 feet, the Manhattan portion of the subway would be above the high tide, a level which made mechanical drainage equipment unnecessary. Since Elm Street lay near the City's drainage dividing line, the problem of relocating the sewers intersected by the subway would be considerably reduced, an additional economic realized.76
Beyond the modifications presented, Parsons envisioned that the remainder of the route could be built in accordance with the earlier plan. The Court approved this new proposal, subject to a number of financial conditions which were not met until November, 1899. This done, the Board of Rapid Transit Commissioners authorized the drafting of formal specifications that could be inspected by contractors interested in constructing the railroad. The route finally adopted called for the subway to begin, "at a point at or near the intersection of Broadway and Park Row [page 234] and proceed North beneath Park Row and Centre Street to New Elm Street. After traveling beneath Elm Street as far as Eighth Street, (Astor Place) the line was to proceed north beneath Fourth Avenue until Union Square (14th Street) was reached. From 14th Street to 42nd Street the road was to travel under Park Avenue. Upon reaching 42nd street the line was to travel west beneath 42nd Street as far as Broadway. Between 42nd Street and 190th Street the route followed first Broadway and, after crossing 167th street, Eleventh Avenue. North of 190th Street, Elmwood Street and Broadway were to carry the line across the Harlem Ship Canal and into the Bronx. An east side route was to diverge from the Broadway line at 103rd Street and proceed east under Central Park to the intersection of Lenox Avenue and 110th Street. The subway was to continue north beneath Lenox Avenue as far as 141st Street where it was to cross under the Harlem River and emerge as an elevated road, traveling via Westchester Avenue, Southern Boulevard, and Boston Road to the northeastern terminus at Bronx Park.78 The contract divided the construction into four sections, so that if funds for the entire line were unavailable, construction of a portion or portions of the line could begin. The four sections were:
In November of 1899, the Board of Rapid Transit published an "Invitation to Contractors" formally soliciting bids for the construction of the proposed rapid transit subway.80 Engineering journals criticized the format of the invitation. The Engineering News was convinced that no contractor was in a position to equip and operate the road as the contract specified. The Engineering Record argued that constructing the subway, "at a time when materials are unprecedentedly high" and in a city where the compliance with "state and city labor laws... considerably increases the cost of work" would diminish the enthusiasm of any contractor to bid on the project.81 [page 235] Two contractors, Andrew Onderdonk and John B. McDonald, did submit bids to construct and operate the New York rapid transit subway. Mr. Onderdonk and his son, a civil engineer, operated the New York Tunnel Construction Company.82 McDonald was a railroad and public works contractor who had performed construction work for the Baltimore and Ohio, Pennsylvania, West Shore and Potomac Valley Railroads between 1881 and 1889. In 1890, when the Board of Rapid Transit was first at planning the subway, McDonald began the construction of the Baltimore Belt Railroad, successfully completing it in 1895. At the time McDonald bid on the subway, he was working on the Jerome Park reservoir. In February, 1900 the Board of Rapid Transit announced that he had been selected to construct all four sections of the subway.83 The size of the project, the variety of the structures to be constructed and the terrain to be worked, and the general desire to complete the project in as short a time as possible,84 prompted the contractor to divide the project into fifteen sections, "the beginning and ending of these several sections being fixed by local conditions necessitating variations in the construction."85 Individual sections were then placed under the jurisdiction of sub-contractors. Steel erection all along the route was contracted to one firm, Terry and Tench Company. The work of relocating and reconstructing the sewers, the first step, was distributed among a number of small sub-contractors.86 Two of the biggest contracts were for furnishing structural steel and cement. The Carnegie Steel Company undertook the manufacture of the 74,326 tons of structural steel and 4,000 tons of rail required to construct the subway. The contract required 22,439 tons of steel beam, 20,466 tons of rivet steel, 7,921 tons of steel column, 23,500 tons of steel viaduct, and 4,064 tons of rail. United Building Materials Company was awarded the contract to supply McDonald and his sub-contractors with 1,500,000 barrels (300,000 tons) of cement. In 1895, the total amount of cement consumed in the United States was less than 100,000 barrels. The largest portion of the cement was used in making concrete. Mixed with twice as much sand and four times as much crushed stone, the engineers estimated that 400,000 cubic yards of concrete would be produced for use in constructing the subway. These two contracts were "the largest ever undertaken by an individual firm for supplying cement and steel for a single engineering work."87 The contract between McDonald and the Board of Rapid Transit consisted of ninety-four pages of basic construction specifications accompanied by three volumes of maps and drawings. The contract described not only the route and the type of construction to be followed, but also the specific materials to be used in constructing the subway, and methods of construction permitted.88 [page 236] The contract permitted open excavation (cut and cover) construction and tunneling. Open excavations were not to exceed 400 feet in length unless covered to permit the passage of pedestrians and vehicles. Open excavation was permitted between the southern terminus at City Hall station and 34th Street. Tunneling was required between 34th and 40th Streets and on the east side route from 104th Street, beneath Central Park, to Lenox Avenue and 110th Street. Open excavation was permitted along 42nd Street, and on the west side as far north as 60th Street. North of 60th Street the contractor could choose "the most expeditious manner possible, having due regard to safety of persons and property and reasonable consideration for the accommodation of street traffic."89 Having studied the deep tube, intermediate depth, arches of masonry, and shallow flat roof or "Arcade" style tunnels, the Board chose the latter. Chief Engineer Parsons explained, "weighing all the advantages and disadvantages, your Engineer recommended the adoption, so far as possible, of the shallow excavation type on account of the greater convenience when completed and probable less expense to construct.90 The Board's preference for a shallow tunnel railway received tangible encouragement from the example of the Boston subway. In 1895, Boston began constructing an underground right of way for a portion of its electric street car line. Boston desired to decrease the congestion of its downtown streets and increase the rapidity of streetcar travel. To accomplish both objectives, the city decided that in the most congested area the streetcar tracks should be relocated beneath the street. To assure maximum accessibility, the "Arcade" or shallow depth tunnel was chosen. Like the recently completed Budapest railway, the Boston engineers used steel beams with concrete arches between them in constructing their flat roof tunnel. The Boston tunnel introduced steel columns with concrete arches between them into the side walls as well.91 In New York, however, "abrupt changes in topography and geological formation" prevented shallow construction everywhere. Between City Hall and 31st Street, 41st Street and 122nd Street, 135th and 150th Street, and beneath Lenox Avenue, the structure was built close to the surface. Between 33rd and 40th Streets, the presence of the Metropolitan Street Railway's Park Avenue tunnel necessitated dividing the subway and passing the tracks under Murray Hill in two separate concrete-lined tunnels. The need to maintain reasonable gradients also necessitated tunneling beneath Central Park between Broadway and Bronx Avenue, and on the west side, between 150th and 155th Streets, and from 158th Street to Fort George. Depressions of the topography required the construction of a viaduct between 122nd and 135th Streets. Topography and economics encouraged the use of an elevated structure on the west side, north of Fort George, and on the east side north of Melrose Avenue in the Bronx.92 [page 237] Different types of construction were used in building the subway. The majority of the tunnel, 10.6 miles or 52.2% of the Contract One road, was constructed with a flat roof of steel I-beams and transverse concrete arches. Steel I-beams, spaced five feet apart longitudinally, served as side wall columns and horizontal ceiling beams. Between the I-beams, concrete arches were formed. Four bulb-ended steel angles, six inches in width, were riveted together to form a single bulb-angle column. The bulb angle columns were placed between the tracks to carry the steel roof beams. Knee braces were used in connecting the bulb angle columns and the roof beams. The steel frame rested on a concrete foundation, the full width of the subway, with a minimum thickness of eight inches. Granite footing stones within the concrete foundation supported the bulb angle columns located between the tracks. The steel beam and concrete structure allowed either the full or a partial width to be built, "with an absolute certainty that the several sections will fit together, connections between the rigid members being made of plastic and easily molded concrete."93 The entire structure, top, bottom, and both sides, was coated with a thick layer of waterproofing, eight layers of felt and asphalt paper, applied prior to backfilling and resurfacing the street. A modification of the standard steel beam and concrete structure was used in constructing the subway beneath Lenox Avenue. The steel I-beams normally used in the side walls and roof were replaced by one-and-an-eighth to one-and-a-quarter inch thick steel rods embedded in the concrete. The rods were spaced from four to ten inches apart and surrounded by eighteen to thirty inches of concrete, depending upon the load the roof was expected to carry.94 [page 238] Standard bulb angle columns located between the tracks added support to the roof. Four and a half miles, 23% of the subway, was built as a concrete lined, arch tunnel. Five miles, 24.6%, operated above ground, running upon a steel viaduct. Cast iron lined tubular tunnels carried the subway beneath the Harlem and East Rivers.95 With the route and type of structure decided upon,"
To assure adequate supervision of the sub-contractors, the sub-contract sections were organized into four engineering divisions:
A Sewer Division was also created to supervise the work of relocating and reconstructing the sewer and drain system.97 The first shovel of earth was turned at City Hall Park in ceremonies held on March 24, 1900. The next day work on the 20.5 mile subway began in earnest. The first step in constructing the subway was relocating all the sewers and storm drains intersecting the right of way of the subway. The Chief Engineer estimated that 7.2 miles of sewer along the right of way and 5.13 miles of sewer beneath other streets would be reconstructed.98 Manhattan's sewer system was the combined type where both sanitary sewers and street storm drains connect and discharged together. The sewers ran beneath the streets and avenues where they discharged into larger, lower level mains whose final outlet is in either the North (Hudson) or East Rivers, depending upon the specific gradients and topological conditions of each local area. Since constant expansion and frequent alterations made the records of the Sewer Department cumbersome and confusing to work with, the contractor undertook a comprehensive sewer survey. The sewer division engineers sought to locate all sewer mains and outlets, measure every manhole for depth, determine the flow, drainage, area covered, and run-off of each locality, and wherever possible, examine the internal condition of the sewer mains along their entire length. The engineers concluded that since the path of the subway bisected Manhattan along a north-south axis the [page 239] the best solution was to accept this division and direct the flow of the sewers on the east side of the line to the East River and all sewers on the west side of the line to the North (Hudson) River, unless gradients prohibited this practice. This system resulted in the construction of sewers running parallel to the subway which then emptied into the existing low lying mains.99 The need to construct the sewers in accordance with a multitude of specific local conditions produced a sewer system that lacked a uniform method or type of construction, varying instead as local conditions dictated. The finished sewer system used all of the standard types of sewer construction as well as few novel designs created to overcome the problems encountered at Canal Street and Chatham Square, and 110th Street and Lenox Avenue, and Railroad Avenue and 149th Street. The construction contract specified that sewers be constructed of either arched brick masonry or vitrified concrete or iron pipe, whichever way was most appropriate for each section.100 Wooden stave (circular) and wooden box construction were permissible where conditions necessitated, primarily at the East River disposal outlet. Concrete sewers, costing as much as one third less than the conventional brick arch sewers were also constructed. The Engineering News described the construction of concrete sewers:
Combinations of concrete and brick construction, where concrete inverts (bottoms) carried a roof arch of brick, were also used. There were points at which the sewers had to be carried across the path of the subway or where the large size of the sewer required special construction. Canal Street, 110th Street and Lenox Avenue, and Railroad Avenue and 149th Street were the most prominent examples of special work. The Canal Street sewer, draining an area of 180 acres, had previously emptied into the Hudson River. With the construction of the subway, the Canal Street sewer had to be diverted to the East River and a new outfall line constructed. The sewer started as a five and a half foot circular brick sewer beneath Canal Street, expanded to a six and a half foot sewer beneath Chatham Square, Leonard, and Madison Streets, became a box sewer between Madison and South Streets, and was finally funneled into two circular wooden stave pipes at its outlet at the East River. With the exception of the Chatham Square section, which was built in tunnel, the Canal Street sewer was constructed in an open cut. Because of the heavy street traffic and the large number of street railway tracks, the thirty foot section beneath Chatham Square was built in tunnel. The diameter of the tunnel was only six and a half feet, but the fine sand that was penetrated and the fact that the tunnel was only thirty feet beneath the surface complicated the task.102 At Lenox Avenue and 110th Street, a six foot six inch diameter circular brick sewer, draining 124 acres of the west side of Manhattan, was intersected by the subway. A new sewer of equal diameter, but to a depth sufficient to pass beneath the subway was constructed on either side of the subway structure. Where the sewer passed beneath the subway, the brick sewer was replaced by three 42 inch diameter cast iron pipes. [page 241] An objective of the sewer division-engineers was "to arrange for the permanent flow of sewerage without pumping."103 Only one sewer was reconstructed below the tide line, necessitating the use of a siphon to assure proper drainage. In crossing beneath the subway at Railroad Avenue and 149th Street in Manhattan, the sewer dropped below the tide level. Two siphons were built so that should the sewer prove not to be self-cleaning, one siphon could be shut off and cleaned while the other continued to function. During the first few months of sewer reconstruction, the engineers and contractors organized the work force, procured the equipment, and arranged for the delivery of the materials needed for the actual construction of the subway. All but one sub-contractor agreed that the economical and efficient use of pneumatic tools hoists, drills, pumps, concrete mixers, and riveters required a central air compressor power plant for each section or groups of sections. To satisfy the need for compressed air, nine central compressed air stations were constructed.104 The heavy volume of street traffic, the presence of large buildings with footings resting on sand close to and above the bottom of the subway excavation, and the complicated design of the City Hall station and turning loop, made section 1 especially costly, difficult, and tedious to construct. The original plans for section one called for the four track line to continue south past the Brooklyn Bridge station and form a two track turning loop around the United States Post Office building. The decision in 1900 to extend the line down the east side and into Brooklyn brought about an alteration in this design. The revised plans called for the two interior or express tracks of the main line to continue to Brooklyn while the two exterior or local tracks dropped below the main line, veered west a short distance, and formed a single track turning loop beneath City Hall Park.105 The loop under City Hall Park was the first part of section 1 to be excavated. The loop, unlike the steel frame portions of the subway passing beneath Park Row, was a concrete arch structure with a width of 11 feet and a height of 14 feet, 10 inches. The excavation was open cut work except for that portion of the loop passing under the vaults of the Post Office Building and the ten story New York Times Building. Tunnels were driven beneath these two structures. The entire excavation for the loop, as was all of sections 1 and 2, was in soft, loamy sand, which was removed by hand shoveling. In excavating sections 1 and 2, the methods varied depending upon the volume or surface traffic and the extent to which a particular street could be closed to traffic.106 The heavy volume of street railway traffic on Park Row prohibited its being closed. It was necessary to dig four narrow trenches parallel with the street, one on each side of the street railway line and one each outside the line where the exterior wall of the subway structure would be built. When the trenches were six or seven feet beneath the street railway track, horizontal tunnels, perpendicular to the line of the railway and the trenches, were dug and the street surface supported by short timbers. Through these transverse tunnels, spaced at ten-foot intervals and between the locations where the actual subway columns and girders would be erected, 14 by 14 inch timbers or "needle beams" were placed. These needles beams were wedged up against the roof of the tunnel and held firm by temporary timber supports. Beneath these transverse beams, a half-dozen six by six foot shafts were then dug to a depth below the projected foundation grade of the subway structure. Timber columns, twelve inches square, were set in these shafts and wedged tight against the transverse needle beams. After the columns were in place and carrying the weight of the beams and the street above them, the remaining earth could be carefully removed and the trench excavated to the full depth and width required by the subway structure. Construction could then proceed while [page 244] traffic on the street above continued to flow uninterrupted by. Along Elm Street light traffic and the lack of asphalt paving permitted the contractor to close the street and excavate the full width of the subway without concern for maintaining a roadway above the excavation. Section 1 and 2 were excavated entirely in sand. In section 3, rock at a level interfering with the subway structure, necessitated different methods of construction. The rock, first encountered at 10th street, gradually rose closer the surface until it was within three feet of the street and "directly beneath the yokes of the electric railway... at 15th Street."107 The excavation of the remaining portion of section 3 was through rock of varying depths. To minimize the disruption of traffic, the initial cut and cover construction in section 3 was limited to one half of the street. However, "as the work progressed it was found that the inconvenience resulting from the excavation on one side of the street was felt with almost equal force upon the other, and that the building of the railway half at a time produced almost as much interference with street traffic as would the building of two railways."108 Excavation of the full width of the street was subsequently permitted. Temporary steel and wooden bridges allowed the orderly, if restricted, flow of streetcar and vehicular traffic above the excavation. The streetcar tracks were carried on temporary trestles while excavation and construction progressed below. In building these temporary trestles, trenches were dug at intervals of forty feet transverse to and beneath the streetcar tracks. Upon reaching the depth of the subgrade of the subway, concrete footings were poured in the trench and a timber trestle or bent erected. Along the outside and between the middle of the streetcar tracks, 24 inch steel beams, forty feet in length were laid longitudinally in a trench dug just below the bottom of the tracks. The beams rested upon the tops of the previously constructed timber trestles. Transverse to the street tracks, trenches dug so that cross beams beams could be inserted beneath the tracks and fastened to the longitudinal I-beams by rods and bolts. Once a sufficient number of transverse cross beams had been placed to carry the weight of the tracks and securely tightened, the excavation of all the remaining earth and rock could begin. This system of carrying the streetcar tracks permitted the total excavation of the street. The construction of the subway could proceed with only one interruption every forty feet. After the subway structure was completed, brick piers built on the roof of the structure carried the weight of the streetcar tracks while the trestles were removed, the excavation backfilled, and the pavement restored.109 [page 245] Overhead cableways were used extensively in sections 1, 2, and 3 to remove the excavated material or "spoil." Derricks were placed where large masses of rock and earth were to removed. The derricks hoisted the steel buckets full of spoil out of the trenches and to the surface. Once on the surface the buckets could be attached to the cableway, elevated from the ground, and moved along the length of the system to the end of the excavation where the spoil was dumped into horse drawn carts for removal to any of several disposal sites.110 In the area of Union Square, the entire area below the level of the streetcar tracks was solid rock. A pedestrian bridge over the excavation, a stiff leg derrick for removing rubble from the excavation, and a multitude of air compressor lines [were used in construction].111 To avoid damaging the streetcar tracks when using dynamite to excavate for the subway the tracks of the streetcar line were removed to the east side of 4th Avenue. After the relocation of the streetcar tracks, sufficient space was available to excavate and construct the two southbound tracks of the subway. The completion of the southbound side of the subway permitted the relocation of the streetcar tracks to their original position, and the construction of the remaining two, northbound, tracks of the subway. Section 4 presented the engineers and contractors with the most vexing problems. This section passes beneath a rocky elevation known as Murray Hill. In 1900, this neighborhood contained some of the most prestigious residences in Manhattan. Geologically, Murray Hill is a surface formation of mica schist rock whose strata lie at an angle of 45 degrees. This formation is subject to slides when sufficiently disturbed, and two such slides occured during construction. The contract for section 4 called for the subway to be entirely in tunnel from 34th Street to 41st Street. Complicating the construction was the presence of a two track tunnel used by the Metropolitan Street Railways. This tunnel under Park Avenue necessitated separating the four tracks of the subway and arranging them into two double track tunnels. The two pair of tracks were located beneath and at the sides of the Metropolitan Railway tunnel. [page 246] The first step in constructing the tunnels was to sink four shafts, one at each end of the tunnels. The shafts were located on the side of the streetcar tracks at each end of the tunnel. A strong timber platform was built over the street, connecting the two shafts. This timber platform carried the equipment needed to operate the compressed air drills used in driving the tunnel. The two shafts at the south end of the tunnel were the first to be sunk. Work began on the east tunnel shaft on September 17, 1900 and on the west shaft on October 15, 1900. These two shafts were thirty feet long, twenty feet wide, and directly over the route of the tunnel. The south shafts penetrated a solid strata or rock that required no timbering. Using air drills and dynamite to break the rock loose, and stiff leg derricks to excavate the spoil, work progressed without incident. The final depth of the two shafts, 24 feet, was reached within four months. The two north shafts required timbering as they hit both rock and layers of hard earth. Although smaller than the south shafts they were sunk to a deeper depth, 38 feet. On December 11, 1901 the driving of the west tunnel began from the south shaft. This tunnel was driven using the "top heading" method. Figure 1 indicates the sequence used in driving the tunnel by method. In driving the east tunnel northward a "bottom drift" was employed. The rapidity with which the east tunnel was driven northward using the bottom drift, prompted the contractor to discontinue using the top heading in the west tunnel and proceed with a bottom drift there as well. Figure 2 indicates the sequence of the excavation using the bottom drift. After the initial excavation (portion 1) the tunnel was widened by removing rock on both sides (portion 2). The removal of portion 3 followed, and lastly, the upper portion, number 4 was removed. Because of the very soft and decomposed rock encountered in driving the east and west tunnels south from 41st Street, the top heading was initially used on both. Here permanent timbering was also necessary. Improvement in the rock in the west tunnel permitted the contractor to substitute the bottom heading (Figure 2), while maintaining the top heading in the east tunnel. The method of driving the Murray Hill tunnels differed from the conventional practice of American rock tunneling, which, with few exceptions; were driven using the center top heading pattern. The Murray Hill tunnels used the bottom drift method, wherever possible because, according to Chief Engineer Parsons, it was more economical and permitted more rapid excavation.112 In driving the tunnels, compressed air drills bored holes about seven feet deep with a diameter starting at 2 and 3/4 inches and tapering down to 1 and 3/4 inches. These holes were filled with small charges of dynamite and blasted. Throughout the driving of the Murray Hill tunnels, dynamite blasting presented major problems. The windows of buildings adjacent to 34th Street suffered considerable damage, which prompted the contractor to cover the shafts of the tunnels with heavy timbers. Deflecting the air flow in this manner considerably reduced the problem. Deeper holes were also bored so that rock [page 247] itself would bear the burden of the explosive shock and reduce the vibrations experienced at the mouth of the shaft.113 While the driving of the tunnel differed at each end, the method of removing the excavated materials was similar at both ends. Three parallel narrow gauge tracks were laid on the floor of the tunnel and advanced to the face of the tunnel excavation. Small flat cars upon which steel boxes (skips) were placed, carried the excavated material between the face of the tunnel excavation and the shaft, where the surface derricks lifted the skips to the street. The material from the bottom portions of the tunnel was loaded into the excavation by hand. In removing the material from the upper portions of the tunnel, a "traveler" or rolling platform was used. Mounted upon this wooden platform were air drills and temporary roof support columns. The platform was moved back when blasting thus allowing the rock to fall upon the tunnel floor where it could be loaded into the excavation cars. Lining the two tunnels with concrete presented an entirely new set of problems. The first problem was to establish an adequate concrete mixing facility. Stone crushing machinery was elevated above the street on heavy wooden platforms, and the concrete mixing machinery was placed within the vertical tunnel shaft. The stone removed from the tunnel was hoisted to the surface, transferred to cars, and pushed to the crushing machine on tracks laid upon the elevated platform. Once crushed, the stone was sent to the mixing machinery located within the shaft. The stone, sand, and cement were dumped down the shaft and funneled into a rotating mixer held aloft by a wooden framework. The mixed concrete could be discharged directly into the steel skips and pushed along the tunnel to wherever it was needed. The footings for the tunnel sidewalls were poured first. These footings extended approximately 18 inches into the tunnel from the sidewalls. Rails were laid upon this concrete base to carry a rolling platform or traveler. Three travelers were used: one to build the sidewalls, one to carry a derrick, and a third for forming the roof arch. The first wooden platform carried the wooden lagging or forms which shaped the sidewalls. This platform was rolled to where the sidewalls were to be constructed. The forms were placed, and the traveler secured against movement. Concrete was then shoveled between the rock and the form and the sidewalls were constructed. After the concrete hardened the form was moved forward, and the next section of sidewall was poured. After the sidewalls were constructed the derrick and the roof arch traveler advanced. The derrick moved between the sidewall and roof arch platforms, lifting the concrete into a position where workers could shovel it into the forms. The roof arch traveler provided the forms for lining all of the tunnel above the previously constructed sidewalls. The roof arch forms were placed, then concrete was shoveled through the top of the form until the concrete on both sides reached the crown of the arch. Starting at the rear and working forward, the concrete was shoveled and rammed into the crown of the arch until the entire area behind the form was filled. [page 248] Accidents plagued section 4. On January 27, 1902, the first of a number of fatal accidents occurred. A large but undetermined quantity of dynamite, stored at the north end of the section (41st Street) exploded. Five persons were killed and a number of buildings extensively damaged by this explosion.114 Less than two months after the explosion on 41st Street, a severe rock slide occurred between 37th Street and 38th Street beneath Park Avenue in the east tunnel. The Engineering News reported the event:
The accident alarmed adjoining property owners and focused public attention of the hazards of subway construction. A vigorous campaign waged by property owners followed resulting in the Board's appointing a committee of engineers to investigate the cause of the accident and recommend action to insure against recurrence. [page 249] The investigating committee consisted of five civil engineers, two appointed by property owners, one by the Board of Rapid Transit Commissioners, one by the Chief Engineer of the Commission, and William Parsons as Chief Engineer. The report of the engineers concluded that work could continue in the east and west tunnels provided their precautions were followed.116 Work was resumed in accordance with the recommendations of the engineering committee and safely pursued until June 17, 1902, when the final fatal accident on section 4 occurred. During an inspection tour accompanied by Chief Engineer Parsons, Ira A. Shaler, the sub-contractor of the section, was severly injured. Parsons' diary describes the accident.
Two weeks later, Ira Shaler died. The second engineering. division included 4 sub-contract sections, numbers 5a and b, and 6a and b. Section 5 began at the center line of 41st Street and Park Avenue, extended north to 42nd Street, and curved west beneath 42nd Street. This section continued west under 42nd Street until it intersected with Broadway. At Broadway, the line turned north and continued up along Broadway to 47th Street. The center line of 47th Street marked the end of section 5a. Work on section 5a began on February 25, 1901. The start of work on this section was delayed by negotiations between the New York Central and Hudson River Railroad Company and the Board concerning a possible joint station at 42nd Street. When months of negotiation with the New York Central produced no agreement, work proceeded according to the original plans. The terrain in section 5a consisted of a five to fifteen foot layer of densely packed earth over solid rock. The major problem in section 6a was the multitude of large sub-surface obstacles: 48 inch water pipes, sewer mains, and electrical conduits and the electric railway tracks running along, and intersecting with, 42nd Street. Two tracks ran along 42nd Street, while lines crossed it at Park, Sixth, and Broadway. Large buildings on both sides of the subway right of way also posed problems. A number of buildings along 42nd Street maintained underground vaults extending as far as eighteen feet into the projected path of the subway, as did the foundations of the elevated railway station at 42nd Street and Sixth Avenue. [page 250] While the presence of so many varied surface structures made construction in section 5a difficult, the subway structure itself was not unusual. With the exception of a small portion at the eastern end of the section, where it emerged from the Park Avenue tunnel and curved west beneath 42nd Street, section 5a was the standard four-track, steel bent structure. Differing excavation techniques were used, depending upon the specific surface and sub-surface impediments encountered. The property under which the subway zig-zagged from Park Avenue and curved west below 42nd street was privately owned. This property was condemned, and the subway was built in an open cut. The section of subway between Park Avenue and Fifth Avenue included a station and a fifth track built for switching operations. Consequently, this section of the line was wider than most other portions of the standard four track line. The depth of the excavation between Fifth and Sixth Avenues varied from 25 to 35 feet below the surface of the street. Generally between ten and twenty-seven feet of the excavation penetrated solid rock. In excavating this portion of section 5a, a 15-foot wide trench was dug longitudinally along the south side of 42nd Street. This trench was sheeted and braced in the usual manner, and then steelwork for a single track was erected. At frequent intervals, however, roof arches were left unturned so that the rubble from subsequent lateral excavations might be removed. Once this single track was completed, transverse drifts north below 42nd Street were begun. These lateral excavations were at the level of the subway roof and driven north approximately 20 feet, to a point where the third row of steel columns would be erected. After this drift was sheeted, 24 inch steel beams were inserted into the drift, one end lying on the roof of the subway and the other resting on the rock within the drift. With the underpinning securely in place, the space to be occupied by the subway structure was excavated, the structural steel erected, and the roof arches formed. Naughton and Company constructed section 5b, from the center of 47th Street north beneath Broadway as far as 60th Street. Work began on September 20, 1900, mostly through rock with a shallow cover of earth, and with the additional problems of a double track electric street railway line running along the middle of Broadway, and a multitude of sub-surface pipes and sewers. The contractors first excavated the space between the curb and the streetcar line. Lateral excavations beneath the tracks, supported by wooden posts, permitted the construction of one half of the subway structure. After the pavement was restored over the completed half of the subway, the same method was used to construct the other half. What made the work of section 5b unusual was the necessity of constructing the line beneath the 724 ton, 75 foot high monument to Christopher Columbus located at Broadway and 59th Street.119 The Columbus monument is a large granite statue carried upon a 50 foot high shaft. The shaft is mounted on a three-tiered pedestal. The foundation is a 45 foot square, 14 inch deep pad of concrete and brick masonry. The first step in building the subway under the monument was to sink two shafts, one each on the north and south sides of the monument's foundation. These two shafts were carried to a depth three feet below the foundation-line of the subway construction. A tunnel 6 feet wide and 7 feet high was driven from these two shafts out beneath the foundation of the monument. Upon the tunnel floor concrete was laid and 12 by 12 wooden columns were placed between the concrete floor and the foundation of the monument. With this temporary wooden underpinning in place, workmen built a solid masonry foundation. A large steel girder, resting on two wooden trestles, was then placed beneath the eastern edge and wedged tight against the monument's foundation. The relation of the completed subway structure and Columbus monument is most clearly defined in drawing 191. Section 6a and b were awarded to sub-contractor William Bradley. The material excavated along this portion of the line consisted of a layer of earth and rubble covering rock. Section 6a and b differed considerably from the four track line constructed in sections one through five. The standard steel-frame, four-track structure was carried north in section 6 as far as 96th Street. Ninety feet north of 96th Street, the interior, or express, tracks descended and the exterior, or local, tracks ascended. Between 103rd and 104th Streets the express tracks swung east, passing beneath the uptown local track. The two tracks veering east at 103rd Street formed the east side line into the Bronx. The two exterior tracks, separated at 96th Street, continued north beneath Broadway. At 100th Street a third track was added to the [page 251] two already coming up Broadway. This third track carried blocking which supported the street surface. Once these were in place and the street was sufficiently supported, the contractor excavated the rock and erected the columns and roof beams for another track. He repeated this procedure until the steel frame and roof for all four tracks was completed. This continued as far as 135th Street where a large storage yard was located. In both 6a and 6b, open excavation was the predominant method of construction. The street railway tracks were supported on wooden truss bridges, as in section three.120 [page 252] The east side line and engineering division 3 began with section 7, which curved east from Broadway under private property from 103rd Street and Central Park to Lenox Avenue and 110th Street. Section 7 was a double track tunnel through rock, except for a short portion of open cut. The contractor easily tunneled section 7, as the rock was solid mica schist, bearing little water. The contractor drove the tunnel using two shafts and one portal. The use of a portal was made possible by the abrupt sloping of a rock ridge into a deep ravine in Central Park. Mules pulled small railroad cars loaded with rubble to the shafts, where a heavy elevator hoisted the rock-laden cars to the surface. Work progressed rapidly because of two 8-hour shifts on the headings served by the shafts and one 8-hour shift on the portal heading. Approximately 100 feet of section 7 was built using open cut methods. Once the cut was excavated, a two track concrete arch was formed.121 Fallen rock and rubble was loaded by hand into the mule drawn cars, pulled beneath the traveler to the shaft-head, and removed to the surface. Section 8 extended from 110th Street to 135th Street under Lenox Avenue. Two contractors, Farrell, Hopper and Company and John C. Rodgers built this section. Farrell, Hopper constructed the portion between 110th Street and 116th Street, sub-letting the portion between 116th Street and 135th Street to Rodgers. In section 8, the subway traveled in a two track, flat roof, reinforced concrete structure. The structure was located on the west side of Lenox Avenue, between the west curb and the street railway tracks that occupied the center of the avenue. Four stations were located within this section. Section 8, built through sand and sand mixed with gravel, offered few serious difficulties. Much of the sand was of a high enough quality to be screened, washed, and used for mixing with concrete and mortar. Because of the width of Lenox Avenue, the relatively low level of development along this portion of the line, and the nature of the excavated material, no unique methods of construction were employed. The standard procedure was to sink a single trench to the foundation grade of the structure, brace and sheet the sidewalls, lay the concrete foundation, erect the steel, and concrete the roof all within this single trench.122 The only thing worthy of note in section 8 was the reliance upon mechanical devices different from those used for other sections. The location of the subway on one side of the avenue, and the absence of street railway tracks above the excavation, made for an easy job. Bridges were required at the intersection of cross streets, but these [page 253] were of routine construction. The contractor could use a locomotive crane to handle the excavated material. This steam powered crane traveled on tracks laid on the street parallel to the excavation. The crane was used for removing the loaded skips and dumping them directly into horse drawn wagons. Along Rodgers' portion of section 8, overhead cableways of varied description were used to remove the material from the trench.123 As his job was the simplest, Rodgers completed it quickly, finishing a two and a half block long section of two track subway and resurfacing the avenue in 90 days. And even with delays in steel delivery, he completed a one-block section of subway in 36 days.124 Steep grades and cast iron tubes distinguished section 9 from the remainder of the Contract One rapid transit subway. The 8,000 feet of section 9 began at 135th Street and Lenox Avenue in Manhattan, ran under the Harlem River, and surfaced in the Bronx at Melrose Avenue. In the portions of this double track section not beneath the river, three types of construction, standard steel frame, reinforced concrete, and concrete arch, were used. Open excavation was permitted for the entire length of section 9 except, of course, for the Harlem River tunnel. In tunneling the Harlem River, twin cast iron tubes were constructed. The two tubes were each 450 feet long with an interior diameter of fourteen feet, and were connected by a vertical cast iron diaphragm. The two tubes were surrounded by a layer of of concrete with a minimum thickness of one foot. The roof of the tubes was covered by a layer of concrete two and one-half feet thick. An order issued by the United States War Department required that the top of the subway tunnel be at least twenty feet below the tide level of the river.125 The grades approaching the Harlem River tunnel were a full three percent, the steepest anywhere along the Contract One right of way.146 An examination of the riverbed indicated the presence of a layer of clay of varying thickness lying above fine silt. The rock beneath the clay and silt dropped sharply at the west bank. The presence of clay, silt, and irregular rock assured the contractor of difficulty and danger should he proceed to drive the tunnel with a conventional shield. He suggested building a rectangular-shaped, submerged coffer dam extending from the shore to the middle of the river and within this caisson-like structure, excavating the rock and earth and constructing the tunnel one half at a time. The Chief Engineer of the Rapid Transit Commission agreed to permit this unique method of tunnel construction, and work on the Harlem River tunnel began from the west side of the river in June, 1901. [page 254] The first step was dredging a channel across the bottom of the river following the projected line of the tunnel. On both sides of this channel, working platforms, carried on piles, were constructed to house compressed air equipment and derricks. Contractor McBean described the remainder of the construction:
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