Route capacity

It may be limited by the worst bottleneck in the system,[1] such as a stretch of road with fewer lanes.

[3] For a metro or a light rail system, route capacity is generally the capacity of each vehicle, times the number of vehicles per train, times the number of trains per hour (tph).

Beyond this mathematical theory, capacity may be influenced by other factors such as slow zones, single-tracked areas, and infrastructure limitations, e.g. to useful train lengths.

Severe snowfalls will reduce the capacity of highways and freeways, and high winds will make landing and departing airports difficult.

For railways with very high passenger loads, the maximum possible route capacity is an important factor.

A common unit for route capacity is people per hour (pph), which can for metro style systems can be as high as 80,000.

A slower rail system will require more rolling stock to maintain a high throughput of trains.

[10] A railway that operates at close to the level of theoretical capacity for extended periods will have lower punctuality (fewer trains arriving when timetabled).

[11] Route capacity depends on the number of passengers using a system, if only because this will affect the length of station stops.

[13] Increasing route capacity for a rail system requires substantial investment in infrastructure.

Mixing different types of trains, or even different stopping patterns, will result in a substantial reduction of capacity.

Freight trains often accelerate and brake more slowly than passenger, and have lower top speeds.

[19] In modern times, Punggol metro line in Singapore uses a moving block system to achieve a headway of 90 seconds, so the route capacity is 40 trains per hour.

Stations in a railway system, and where train are required to stop to pick up or drop off passengers, serves to reduce the route capacity.

Moving block represents a new type of signalling that allows the reduction of headways, and an improvement of route capacity.