President George Washington publicly favored the establishment of roads to promote the westward expansion of our nation. In 1791, the legislature of the Pennsylvanian Commonwealth approved a state-wide transportation plan and a year later created the Philadelphia and Lancaster Turnpike Company. The turnpike charter called for the construction of a 62-mile log-surfaced road, which provided successful transport for settlers and their goods over the muddy territories.
The Lancaster Turnpike route was later replaced by a canal after 1800 and then the beginnings of a railroad in the 1880s. The Allegheny Mountains posed a barrier to William Vanderbilt and Andrew Carnegie, who at the time were building a railroad from Harrisburg west to Pittsburgh to compete with a more northerly route provided by the booming Pennsylvania Railroad. Over one-half of the road bed was constructed and seven tunnels partially excavated before Vanderbilt went broke in 1885.
As early as 1910, ideas arose to convert the abandoned railway route into a motorway. The idea of a turnpike to cross the Alleghenies was supported by the trucking industry as well as the motoring public. In late 1934 the idea of building a new highway along the then-abandoned South Pennsylvania Railroad Company line through the Allegheny Mountains was proposed and President Franklin D. Roosevelt's administration, who was looking for work-relief projects, thought the highway would fit the bill.
A feasibility study began in 1934 with surveyors collecting information and engineers selecting routes and preparing plans. In 1937, the governor signed a bill to create the Pennsylvania Turnpike Commission. America was still recovering from that the great depression, and so President Roosevelt supported the construction on the turnpike to lower unemployment through his WPA. The project wound up being financed by a loan from the New Deal's Reconstruction Finance Corporation for almost $41 million at 3.75 percent. The WPA also provided another $29 million in grants.
The Pennsylvania Turnpike project limits were from Middlesex, located west of Harrisburg, to Irwin, east of Pittsburgh, a distance of 160 miles. For the project to be constructed on schedule in a mere 20 months, 1,100 engineers were employed. Noteworthy was the consistency of the design standards of the turnpike, much different than previous piecemeal attempts to build roads through different areas. Plans called for a 200-foot right-of-way with two 12-foot lanes of travel provided in each direction with medians, berms, long entrance and exit ramps, banked curves, and separated grade crossings.
Revisions made during the course of design included changing from two asphalt and two concrete lanes to all concrete lanes. A four-foot median was replaced with a ten-foot one. The maximum grade selected for the turnpike was three percent, which an automobile could easily tolerate but was still much less than the nine to twelve percent grades on local highways. A standard sight distance of 600 feet was chosen. Straightaways were designed for 100 mph and the spiral curves were super-elevated to accommodate 70 mph. Easy grades were carved through valleys, ravines, and mountains. Almost 70 percent of the original turnpike was straight, with the longest a 40-mile stretch west of Carlisle relieved by one curve to break the monotony.
Many innovations were introduced during the layout of the highway. When possible, the turnpike route was laid out on southern exposures to let the sun heat the ice and snow on the roads. Toll booths off of the turnpike were located on downhill grades to allow drivers time to react instead of being surprised. In addition to the roadway, there were over 300 bridges and culverts, nine interchanges, ten service plazas, and eleven toll booths to design.
After plans were completed in October, 1938, 155 construction companies and 15,000 workers from 18 states were under contract with the Turnpike Commission. Initially, planners proposed nine tunnels. But, Quemahoning and Negro mountains near Somerset were both by-passed and seven tunnels made it from the drawing board to construction. Six of the seven original railway tunnels ranging from 3,500 to 6,800 feet had to be completed or widened to allow two lanes of vehicles. Work began at a slow pace due to difficulties acquiring right-of-way, but a year later fifty crews were building a ribbon of pavement at a rate of three-and-a-half miles a day.
