Mass Rapid Transit (MRT) systems are "Metro" and "Commuter Rail" systems "using trains of high-performance, electrically powered rail cars operating in exclusive rights-of-way, usually without grade crossings, with high platform stations" (TCRP, 1998).
- "Metro" is the most common international term for underground (subway) heavy rail transit, though it is also commonly applied to elevated heavy rail systems. Metros are the most expensive form of MRT per kilometre, but have the highest theoretical capacity.
- "Commuter rail" (or "suburban rail") is the portion of passenger railway operations that carries passengers within urban areas, or between urban areas and their suburbs. Passenger cars generally are heavier than Metro or LRT, the average trips are usually longer, and the operations are carried out over part of a railway system.
Read more in the gTKP Urban Mobility Topic Information Sheet on Mass Rapid Transit.