The Federal Transit Administration has classified several different kinds of rail transit. Tell help people tell the difference between commuter rail and heavy rail or between streetcars and light rail, the following table lists the distinguishing features of each type. Click on the name of each mode to read more about that form of rail transit.
|Mode||Distinguishing Feature||Average Speed mph||Capacity People Per Hour||Average Cost Per Mile in Millions||Range of Costs Per Mile in Mlllions|
|Streetcars||Cars can't be coupled into trains||8.2||2,000||46||40 to 60|
|Light Rail||Trains that sometimes run in streets||15.6||9,000||137||80 to 350|
|Heavy Rail||Exclusive rights-of-way||20||50,000||440||250 to 2,200|
|Commuter Rail||Rush-hour trains on freight or former freight tracks||32.7||20,000||36||7 to 70|
|Hybrid Rail||All-day trains of Diesel-powered railcars on freight or former freight tracks||23.6||6,000||20||10 to 40|
|High-Cost, Low-Capacity Rail||Light-rail train lengths on exclusive rights-of-way||23.6||9,000||400||300 to 630|
|Automated Guideways||No human driver||8.9||8,000||100||50 to 150|
The capacity shown for light rail is for cities that operate three-car light-rail trains. Portland city blocks are too short for three-car trains, so trains are limited to two cars, reducing capacities to 6,000 people per hour. Salt Lake City blocks are long enough for four-car trains, increasing capacities to 12,000 people per hour.
The average cost and cost ranges for light rail exclude three very expensive subterranean light-rail projects in Los Angeles, San Francisco, and Seattle. The average cost and cost ranges for the high-cost, low-capacity rail (which is not an official FTA category) are based on the Honolulu rail project and Seattle University light-rail project. There have not been any automated guideways built in recent years so the numbers are based on historic costs and the projected costs of building a new Seattle monorail line that was never built.