At 5:55 AM, Saturday, September 11th 1915 the first scheduled electric powered train departed Paoli for Philadelphia marking the beginning of one of the most famous railroad electrification projects in the United States.
At the close of 1910 the Pennsylvania Railroad had certainly accomplished some remarkable projects. The building of Penn Station and the Hudson and East River Tunnels was an engineering feat that put the railroad at a major advantage over many others, giving them direct access to New York City while establishing a through connection to New England markets. Out of necessity the new terminal utilized trains running on a proven direct current third rail system, as steam engines would literally suffocate passengers in the lengthy tunnels. The PRR had already begun utilizing DC propulsion on routes previous to the terminal as a way to economize operations and included subsidiaries Long Island Railroad and part of the West Jersey & Seashore. To the north the New Haven had just inaugurated heavy electrified mainline service utilizing a new alternating current installation in 1907, but with little time to observe the New Haven’s technology the PRR’s conservative management instead chose the proven DC system.
Soon after the New York terminal project was completed, engineering forces turned their attention to a major traffic bottleneck in the PRR’s corporate home of Philadelphia. Broad Street Station, built by the Wilson Brothers in 1881 and expanded by Frank Furness in 1892-93 was a 16-track stub ended terminal that was situated in the city center directly across from city hall. Broad Street saw a host of trains including commuter and long distance trains that stopped, terminated or originated here; because of the nature of a stub end terminal and a lengthily and congested reverse move to the engine facilities west of the Schuylkill River, trains faced a host of delays limiting Broad Street’s capacity and efficiency. In order to ease congestion the PRR turned to engineering consultant Gibbs & Hill to develop a solution utilizing electric traction, but this time with AC propulsion. Now several years into the New Haven’s electrification the PRR could capitalize on their triumphs while incorporating technological advances to perfect the new installation. A simplified infrastructure and commercial power purchased from Philadelphia Electric made AC propulsion very economical over DC which required the railroad to construction dedicated power plants. With a supply agreement in place the PRR and Philadelphia Electric could easily expand the network over the next several years, sharing the power generation expansion cost with other commercial and industrial customers.
The initial phase of electrification would be a costly investment due to the complexities of the Philadelphia Terminal’s trackage. Once completed however, it could not only support electrified Paoli service but also mainline service to Wilmington, Trenton, the West Chester Branch and Chestnut Hill branch freeing up valuable terminal space while maximizing the benefit of the initial cost. Power would be supplied by the Schuylkill River generating station and transmitted across the river to the Arsenal Bridge sub-station then on to the West Philly, Bryn Mawr and Paoli sub-stations. Here the 25 cycle 44,000 volt single phase power would be stepped down to 11,000 volts and fed to trains via overhead trolley lines supported by cable suspension supports strung between tubular steel trolley poles. The route to Paoli was 20 miles in length and electrification included wiring a coach yard and service facility in the West Philadelphia shops as well as a new facility in Paoli, a total of roughly 93 miles of track. Initially limited to just the Paoli commuter runs the electrification would power some 80 plus trains a day while affording an 8% overall increase in capacity at Broad Street. Though this seems like a small advantage for such a significant investment, the PRR looked to the future making this the first of several steps to dramatically increase capacity by expanding electric operations off the initial hub.
While planning, design and construction of the Paoli electrification was taking place, the PRR turned to the proven class P54 steel coach that was already in production. Though only a basic coach design the PRR had incorporated provisions in the plans to accommodate electrification and operating components when it was time to develop a fleet of self-propelled multiple unit (MU) cars. These motorcars would largely makeup the initial fleet of the PRR’s electric operations until suitable locomotives were developed to haul long distance trains. Classified as MP54's many were already in electrified service on the Long Island and WJ&S utilizing DC propulsion. The MP54 fleet eventually comprised of over 1400 cars; 480 ran on the PRR proper, 923 on the Long Island Railroad and 18 on the WJ&S /PRSL, some of which outlasted the PRR itself, remaining in operation through 1981.
With the first phase of electrification a success the railroad continued expansion from the Broad Street terminal, next on the Chestnut Hill branch in 1918 and the White Marsh branch in 1924. Concurrent to the expansion of the PRR’s electrified network other notable projects commenced, one of great importance was the Philadelphia Improvements. With heavy construction beginning in 1927 the PRR sought to replace Broad Street Station with a new subterranean station and office tower called Suburban Station and Penn center respectively. All north-south oriented mainline trains would utilize a new through station on the west bank of the Schuylkill River called 30th Street Station. East-west trains utilized an upgraded facility out on the mainline in North Philadelphia to eliminate the need to reverse out of the terminal to continue after stopping since 30th was actually off the New York-Pittsburgh mainline. Commuter trains in and out of Suburban would also service 30th Street from a separate upper level reducing the concentration of travelers separating commuter operations from the long distance and regional trains.
Though the massive Philadelphia Improvements took years to complete electrification continued at a rapid rate extending south to Wilmington on the mainline including the branch to West Chester in 1928 and north on the mainline to Trenton and the Schuylkill Valley Branch to Norristown in 1930 completing the electrification of all Philadelphia region suburban lines. Further studies reiterated the economical advantage of electrification outside the commuter zones for regional and long distance trains between New York, Philadelphia, Washington DC and Harrisburg, prompting PRR president William Wallace Atterbury to close the gaps in electrification beginning late in 1928. Despite the Great Depression the electrification project continued through 1933, completing the retrofit of the New York Terminal for AC traction and finishing catenary work to complete the network to Wilmington and Paoli. Understanding that Wilmington would not be a suitable southern terminal for electrification, catenary was pushed south to Washington DC including Potomac Yard, financed by a $70 million loan secured from depression era federal recovery programs. Beginning in January of 1934, various reports say up to 20,000 men went to work, comprising of furloughed railroad employees and new hires in the electrical / construction trades to complete the electrification of the New York – Washington DC mainline, which opened for business on February 10th 1935. As a result of the success on the north-south “corridor” the PRR sought to complete electrification from the eastern seaboard west to the Harrisburg terminal including all associated freight and passenger mainlines. Work commenced on the Low Grade from Morrisville to Enola, the mainline from Paoli to Harrisburg, the Columbia Branch and Port Road. Completed in 1938 the entire electrification created a powerful conduit that put the railroad in an excellent position to handle the impending pressure of wartime traffic demands.
The electrified infrastructure of the PRR mainline has remained visibly the same over the ensuing decades despite modifications and renewal. Surviving the Pennsylvania Railroad, Penn Central, Conrail and Amtrak the sub-stations, tubular catenary poles and surviving interlocking towers remain along with many original station buildings preserving the character of the Mainline, a name synonymous not only with the railroad but towns along the route to Paoli. As Amtrak continues to renew their electric traction system the original details of the 1915 electrification, now part of the successful Keystone Corridor could be on borrowed time. There are plans being developed that would call for a total replacement of the 1915 era catenary system. The construction of larger modern support towers similar to those found on the Northeast Corridor will allow Amtrak to move feeder and transmission lines to the railroad right of way much like later phases of electrification did. For now while you ride the Paoli Local or one of Amtrak’s Keystone Service trains take note of the historical infrastructure that survives, that infrastructure around you was part of the one the most ambitious and successful railroad electrification projects in the world!