The Pennsylvania Turnpike was the first American paved highway of the automobile era in which tolls alone were expected to pay all project costs. The 160-mile roadway, which cut an east-west path from Pittsburgh to the state capital of Harrisburg, was considered a revolutionary example of transportation system design and served as a model for the Interstate Highway System.

Motorists had never before seen a road without traffic lights, intersections, and pedestrian or railroad crossings. It was a novel concept that brought 27,000 vehicles on the new roadway the first Sunday it was opened. 

For the project to be constructed in a mere 20 months, 1,100 engineers worked on the design, producing many innovations. For example, when possible, the turnpike route was laid out on southern exposures, allowing the sun to melt the ice and snow on the roads. In addition to the roadway, the design involved over 300 bridges and culverts, nine interchanges, 10 service plazas, and 11 tollbooths. 

Resources  

1. Dan Cupper, "The Road to the Future,"  American Heritage  41 (May/June 1990): 102-111. 
2. Edward J. Trojan, "Pennsylvania Turnpike Ushered in New Generationof Super Highways," Public Works  125 (January 1994): 48-49.