The government's road-pricing plans have economic, rather than environmental motives, writes Dan Milmo

Changing gear: today's Queen's Speech included
plans for a national road-pricing scheme.
Photograph: Scott Barbour/GettyThe contents of the road transport bill revealed in today's Queen's Speech are no surprise. In fact, several British cities including Manchester, Birmingham and Bristol are queuing up to implement the road-charging proposals.

The bill allows local authorities to set up trial road-pricing schemes: from a Ken Livingstone-style congestion charge to the more sophisticated pay-as-you-drive concept.

Despite the increasing political clamour over global warming and the presence of a climate change bill in the Queen's Speech, this is not a green measure. The imperative behind it is purely economic. Congestion costs the West Midlands - an area encompassing Coventry and Birmingham - around £2.2bn per year and authorities there are certain to apply for the £200m in annual funding that the government has made available for road pricing trials.

However, given the scale of the congestion problem in the region and the size of investment needed for a comprehensive road-pricing scheme, this £200m is not enough. A report commissioned by local authorities in the West Midlands estimates that an effective pricing system will cost £2bn to implement, plus a further £2bn investment in local transport infrastructure to ensure that people priced out of their cars are not sardine-packed onto crowded buses and trains.

The same concerns apply for Manchester and Bristol. If the road transport bill is not accompanied by significant public transport investment, it might struggle to reduce congestion. Commuters and casual drivers are the real targets of this bill because most businesses will not stop transporting goods by road. However those who drive to work, or are habitual car drivers, will not abandon their vehicles either, if there is no acceptable alternative.