Medium-capacity rail system

A medium-capacity system (MCS), also known as light rapid transit or light metro, is a rail transport system with a capacity greater than light rail, but less than typical heavy-rail rapid transit.^[1] MCS's trains are usually 1–4 cars. Most medium-capacity rail systems are automated or use light rail type vehicles.

Since ridership determines the scale of a rapid transit system, statistical modeling allows planners to size the rail system for the needs of the area. When the predicted ridership falls between the service requirements of a light rail and heavy rail or metro system, an MCS project is indicated. An MCS may also result when a rapid transit service fails to achieve the requisite ridership due to network inadequacies (e.g. single-tracking) or changing demographics.

In contrast with most light rail systems, an MCS usually runs on a fully grade separated exclusive right-of-way. In some cases, the distance between stations is much longer than typically found on heavy rail networks. An MCS may also be suitable for branch line connections to another mode of a heavy-capacity transport system, such as an airport or a main route of a metro network.