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GRAND CENTRAL ELECTRIFICATION
In 1903, when the Central began planning its Grand Central Terminal electrification, the lure of electric operation was certainly in the air. Trolleys were already taking the country by storm and the first round of electric interurban building was well under way. Chicago had been operating multiple-unit rapid transit trains system-wide since 1900 and the Baltimore & Ohio Railroad had demonstrated the remarkable pulling power of electric locomotives with its Howard Street Tunnel electrification in 1895. The Central had been considering electrification since 1899 but was in no hurry, what with serious questions surrounding the best choice of system.[3] A fatal accident in 1902, however, left no alternative. On January 8 a New York Central morning rush-hour train ran a red light in the smoke-filled Park Avenue tunnel and rear-ended a stopped New Haven train, killing fifteen commuters. The public outcry was so great that the Central moved to action even before the State Legislature, on May 7, 1903, officially banned the use of steam locomotives on the Grand Central line south of the Harlem River after July 1, 1908.
----------------------- The Central formed a commission to study the situation and make recommendations as to the general nature of the electrification. The Electric Traction Commission, as it was named, was well-staffed with engineering talent, including two who would play important roles: the Central's Vice-President and Chief Engineer William J. Wilgus, and reknowned consultant, Frank J. Sprague. The former devised the brilliant two-level scheme for the new Grand Central Terminal while the latter most certainly had a guiding influence (though he downplayed it) in the selection of low-voltage third-rail direct current (d.c.) for the power distribution system. As reported by Wilgus, the group met weekly and set "principles and policies" to be "carried out by a technical corps under the jurisdiction of the electrical engineer."[4]
----------------------- To be sure, there were compelling reasons for the Central's selection of 650-volt d.c. over the competing 11,00-volt single-phase alternating current (a.c.). For one thing, d.c. had already been proven in urban and suburban situations, whereas a.c., despite its acknowledged advantages in efficient line distribution, had not been demonstrated in any major installation. There were more convincing arguments in support of d.c. for the Grand Central Terminal electrification, though: 1) the use of a.c. would require lowering tracks to provide clearance beneath overpasses for the overhead distribution wires, and 2) the clincher, a New York City ordinance prohibited the use of unprotected high tension wires (as in overhead distribution systems).
Another reason given in support of the low-voltage d.c. installation was the "desirability of harmonizing all of the larger electrical installations in the New York vicinity, such as elevated, surface railways and subways."[5] The intention was to provide "11,000-volt three-phase alternating current for high-pressure transmission between the central power stations and the substations, and 600-volt direct current for the low-pressure conductors and third rail."[6] There was even an intimation that a connection might be made with the rapid transit subway (already using low-voltage d.c.) at 42nd Street, the site of the planned new Grand Central Terminal.[7]
----------------------- The Central's commitment to d.c. extended to its suburban electrification, which included radiating lines to Yonkers and North White Plains in addition to the mainline Hudson Division as far as Croton-on-Hudson. Whereas the New Haven Railroad, which shared Grand Central Terminal facilities and approaches with the Central, chose to use 11,000-volt single-phase catenary a.c. once outside the city and on its own right-of-way (and put itself at the cutting edge of railroad electrification technology), the Central planned instead to eventually extend its Hudson Division electrification as far north as Albany with low-voltage d.c. (The superiority of a.c. as a distribution system ultimately discouraged any serious expansion of the Central's electrification. The New Haven, after experiencing early difficulties to the point of nearly abandoning its a.c. system, extended its electrification to New Haven and set the standard to be followed decades later by the Pennsylvania Railroad in its electrification of what is now Amtrak's Northeast Corridor. As of this writing, that system is expected to be extended all the way to Boston.)
A paper presented by Sprague at a meeting of the American Institute of Electrical Engineers on May 21, 1907, provides some insight into the Central's choice of system and the design of the S-motors, so integral a part of the overall plan. What is interesting is that by 1907 many of the claimed advantages of d.c. over a.c. were discounted by at least some engineers, as was evident by the comments of those attending the meeting. Yet Sprague's approach to electrification remained unchanged. Foremost in Sprague's approach was the assertion that the locomotive's motor (Sprague's forte) is the starting point, the key element, the first variable in the design process to be fixed. For Sprague, this pointed to the d.c. motor because of its greater simplicity, efficiency, and reliability. Building on these three factors, the remaining components fall into place: Specifically, the use of third-rail distribution, with its proven reliability, to provide the carrying capacity required by the low voltage; and the design of a locomotive that would exploit the theme of simplicity, efficiency, and reliability to the fullest extent possible. (In support of Sprague's position, the d.c. traction motor has until recently been the de facto standard for today's electric and diesel-electric locomotives.) These above considerations are of paramount importance in any electrification because of the need to write off the project's large initial investment. This was especially true of low-voltage d.c. (with its expensive distribution system), which Sprague characterized as the unequivocal choice for high-density traffic. "The present hope of usefulness of the single-phase system," he said, "is on roads of considerable extent which operate an irregular and sparse traffic, and where only a moderately expensive, or what may be called second-class overhead construction which will keep down the ratio of line investment to that of the balance of the equipment, is tolerable."[8] If Sprague's remark, made in his May 1907 presentation, didn't ruffle a few a.c. feathers, a subsequent remark must certainly have:
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----------------------- The success, if not also the ultimate validity, of Sprague's approach has been borne out by the durability of the Central's electrification and the S-motors in particular. The installation is still in operation and the last of the S-motors survived till the early eighties, after nearly eight decades of virtually trouble-free day-in and day-out service.
This is the second part of an article written in 1992 for Electric Lines magazine, just before it ceased publishing. |
