Norristown High Speed Line

The Norristown High Speed Line (NHSL) is an interurban line system operated between Upper Darby and Norristown, Pennsylvania, USA by SEPTA. The rail line runs entirely on its own right-of-way, inherited from the original Philadelphia and Western Railroad line (still referred to by locals as the "old P&W" and Route 100).

The Norristown High Speed Line is unique in its combination of transportation technologies. Originally chartered as a Class I (steam) railroad, the line is fully grade separated, collects power from a third rail, and has high-level platforms common to rapid transit systems or commuter rail systems such as the Long Island Rail Road or Metro-North Railroad, but has onboard fare collection, mostly single-car operation, and frequent stops more common to light rail systems. Previously, the Norristown High Speed Line was considered to be a light rail line, according to a 2008 SEPTA budget report; however, the line is currently considered a heavy rail interurban line, according to a 2009 SEPTA business plan.

The line was formerly known simply as Route 100, but was officially changed to its current name in September 2009 as part of a customer service initiative by SEPTA.