Definition: Track Gauge

Track gauge refers to the spacing of the two rails used by a trolley or other rail vehicle. Most are built to standard railroad gauge of 4 feet 8 ½ inches. However, some systems (New Orleans, Philadelphia, and Pittsburgh) use a wider track gauge that was adopted in the 1800s when streetcars were introduced. One North American heritage trolley operation (Detroit) used a narrower rail spacing, as its initial cars came from a European city (Lisbon) that used a very narrow track gauge. Cars built for one gauge normally can be converted to operate at another gauge, but the cost can be substantial.