Friday, July 07, 2006

Capability, Choice and Capacity
the three Cs of successful public transport


Key is an ability to go anywhere anytime.

'Anywhere' requires good network coverage, a sensible route structure and easy interchange between services.

'Network coverage' comes down to service being available within reasonable walking distance of home, work, shops and recreation.

A sensible route structure involves direct and easy to understand routes that link major trip generators and transport interchanges with each other and surrounding residential areas.

Easy interchange between services require the following:

- No financial penalties: integrated and multimodal fares
- Co-ordinated timetables: for reliable transfers and minimal waiting
- Easy physical access: a short, safe and direct walk from station to bus stop, preferably unimpeded by car traffic

'Anytime' implies consistently wide operating hours combined with adequate service frequencies. The travel capability required should be reflected in the service frequency provided (as per the previous post). Where services are less frequent than ten or fifteen minutes, a network-wide headway hierachy should be adopted to assure consistent connections.


Choice is obtained by satisfying capability. This is because a high-capability public transport system satisfies a large number of travel requirements. This enhanced flexibility expands choice; many will no longer reflexively reach for the car keys as if this was the only option.

To further increase the number of choice passengers, the service needs to be grown to make it even more convenient and thus car-competitive (two more Cs!). Since total travel time is a major influence of choice, methods such as smart scheduling, frequency upgrades, interchange redesign, bus/tram priority, and express running are all important.


Having provided a high-capability network that many people use by choice, the final problem is meeting this demand through providing sufficient capacity.

In some ways this is a nice problem to have, since it is the opposite of the spiral of declining patronage/declining revenue/declining service/declining patronage that many transit systems saw during 1950/60s.

Depending on infrastructure utilisation, substantial capacity upgrades are not always cheap. However the public transport planner can take some comfort that they are cheaper than freeway projects with equivalent or smaller people throughputs.

Enhancing capability and thus broadening choice should be key themes for public transport advocates. For their part, planning agencies should evaluate the merits of proposed projects on the basis of the capability benefits that they bring.

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