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In Brisbane

A few questions, maybe some others can show some light on it:

1. How high does the charge have to be to get, say, a 1% reduction in congestion at peak hour? I'm trying to get an idea of the elasticity of peak hour traffic.

2. If people shift from car to public transport (presumably at peak hour) how is the public transport system going to cope with that influx? Isn't capacity expansion at peak hour very expensive as all rollingstock and buses are in use? Can the current system handle it?

3. Will this increase 'rat running' through suburban streets because they are less congested/cheaper at peak hour?

Maybe some people might have international examples of experiences they could share.


2. The cost will presumably be significantly less per passenger-km than a road expansion program, if one or the other are required to maintain levels of economic activity around the city centre.

If the choice is the continued status quo of slow, congested travel by car versus uncongested travel by a balance of modes, then the latter might indeed prove more expensive. In that case, an economic appraisal ought to correctly evaluate whether the economic benefits of uncongested travel (less time wasted, plus mitigation of pollution, noise, disruption of other road users, etc.) are worth the expense.


I don't know, I think "making people pay for their congestion" goes over better in some places than "letting people pay to avoid congestion". In NYC at least, this will become "letting the rich pay to avoid congestion while the rest of us ordinary folk sit in traffic", or in two words, "Lexus lanes".



1) I believe the elasticity depends on the type of congestion pricing used and the actual place in question. For urban highways the elasticity is around -0.1 to -0.4 (http://www.vtpi.org/tdm/tdm35.htm).

3) London uses a network of cameras around the charge zone that get effective coverage. The technology is fairly affordable these days. If a cordon pricing policy is used, rat running is of no use. You pay money and time in this case. If it is quicker to rat run then increase the charge until the main roads flow quicker.

Cap'n Transit

All this myopic talk about "elasticity" puzzles me. Driving is in competition with transit. Whether people choose one or the other depends on their relative value (or cost, if you prefer). If transit in Sydney is better than transit in Los Angeles, people are more likely to choose it even if the value of driving is the same.


I'm not sure I like to put this in the traditional government carrot or stick category. Road pricing is an attempt to do with road travel what we do with every other scarce resource - let supply and demand get closer to balance through setting a price. If you charge for bread (which the Soviets discovered has some advantages) you're not doing it to punish bad bread eaters, or to give others special bread access privileges - you're doing it to make sure demand and supply can achieve some equilibrium (and in the case of bread, that you have a way to pay for more bakeries if you need them).

Elasticity is difficult to calculate, since there have not been a ton of examples of congestion pricing, and the details differ. The changes that occur are complex - some people change their time of travel; some move to transit or biking or walking; some use a different route; and some don't make the trip at all. If they move to transit, then more funds are needed to support service, no question. But we want that to happen - and doesn't happen today because use of roads is free.

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