Why is road pricing a good idea?

What Americans mean by a 'McMansion'. Click for slideshow.

I’m not aware of anyone who disagrees seriously with the contention that car travel is underpriced. The consequence of this inefficiency is we drive more than we otherwise would and more than is socially optimal.

The idea of road pricing is that drivers should pay the real costs they impose on others through traffic congestion, pollution, noise and carbon emissions.

There’s also another force at play here which exacerbates the problem of excessive driving. There are some costs that drivers actually do pay – standing costs like depreciation, insurance and registration – that are “disconnected” from the perceived cost of travel.

A person deciding whether or not to drive somewhere will tend to take account of the cost of their time plus petrol, but they usually don’t perceive the standing costs. This under-estimation promotes more driving.

There have been various experiments with road pricing, such as the well known Singapore and London central city cordons (giving rise to amusing interpretations such as this one by Boris Johnson). However this is a technologically outdated approach – transponders and/or GIS technology mean it is now feasible to charge motorists in relation both to distance and traffic conditions i.e by location and time.

A driver who paid a price for a litre of petrol that included both external and standing costs would have a strong incentive to drive less. A gauge on the dash showing the total cost ticking over with every kilometre would provide an even more powerful nudge to think long and hard about the wisdom of driving.

Road pricing can be thought of in simple terms as a two-part per kilometre tariff that recovers both external costs and those standing costs that can be disaggregated. One part is a charge reflecting the general cost of using the roads. The other is a variable price reflecting specific costs like congestion in peak periods.

There are potentially some important benefits for the wider community from road pricing: Read the rest of this entry »