Section 3: selecting suitable rail transit for cities

Urban rail transit can be classified in various ways, such as by spatial location (underground, ground, elevated), track type (heavy, light, monorail), guidance system (steel wheel dual-track, rubber wheel monorail, rubber wheel guided), transport capacity (large, medium, small), isolation from other traffic (fully enclosed, semi-enclosed, open), and service area (suburban, urban, regional rapid).

Key Factor: Transport Capacity

For city planners, choosing the right type of rail transit depends largely on transport capacity.

Large Capacity: For densely populated cities needing massive passenger transfer, the subway is ideal. It carries 30,000 to 70,000 passengers per hour per direction, operates at 40 km/h, with stations spaced 1 to 1.8 km apart. Subway construction is costly, challenging, and time-consuming.

Medium Capacity: If funds are limited but medium transport capacity is needed, light rail or tram is suitable. These carry 10,000 to 30,000 passengers per hour per direction, operate at 30 km/h, and cost about half of subways. Stations are spaced 0.6 to 1 km apart.

Small Capacity: For lower transport demands, monorail is an option. It carries 5,000 to 20,000 passengers per hour, operates at 30 km/h, with short headways.

Suburban Rail for Longer Distances

Unlike subways and light rails for intra-city travel, suburban rail serves commuters between cities and nearby towns/satellite cities. It covers distances from tens to hundreds of kilometers, with stations spaced 10 to 20 km apart and speeds exceeding 120 km/h. Sometimes, suburban rail overlaps with high-speed rail, like the Beijing-Tianjin Intercity Railway.