Participants' cars will be fitted with electronic equipment that will register a charge, with road prices rising on days of heavy atmospheric pollution. The project, part of the European Commission's Eurotoll scheme, is also being tested in France, Germany and Italy, and is based on proven technology.
Driver behaviour is assumed to be influenced by two factors: cost and convenience. As well as introducing road- charging, Leicester's council will change road priorities to make journey times shorter by bus than by car.
Eddie Tyrer, of Leicester council's traffic section, says: "Politically road charging is not acceptable nationally or locally. But if it does come, what we want to see is what it would do, how it might become acceptable, and how it might improve air quality. We also want to determine what price is necessary to create a change of behaviour."
The Department of Transport, one of the partners in Eurotoll, is keen to see tolls introduced on British roads, to reduce excessive traffic on some urban roads and as a way of encouraging more private finance into new road building, especially for motorways. But efforts to create toll roads in Britain have been hit by a series of problems.
Until now the biggest obstacle has been drivers themselves, who simply do not want to pay tolls. The RAC polled motorists and found strong opposition. Jeremy Banks, head of public policy at the RAC, says: "The outcome was that drivers were very strongly opposed to tolling. If it happens, they would prefer toll booths, and would like the money to go to road maintenance and public transport."
But booths would not fit easily on many British motorways, and would slow down traffic flows. Moreover, part of the attraction of tolling is to bring in private capital which, it seems, drivers would resist. And drivers are one of the most powerful vested interests.
What is more, all opinion polls of drivers have shown that tolls will lead to the diversion of traffic, rather than converting drivers into public transport users. Higher car-parking fees in town and city centres has been a factor in the popularity of out-of-town shopping malls. Urban tolls would have the same effect, and motorway tolls could dramatically shift traffic on to trunk roads.
One study predicted that introducing tolls on the M25 could lead to a 500 per cent increase in heavy goods traffic on parallel sections of the A25. While the extent of diversion is dependent on the level of charges, any charge produces a worryingly high level of diversion, according to the studies conducted. And anti-roads campaigners have warned that private motorway developers will be able to set their own tolls. This might lead HGV tolls to be set at deterrent levels so that privately built motorways were geared to car use, forcing heavy lorries on to suburban streets and narrow trunk roads.
The technology is proven, having worked satisfactorily in Germany and the Far East. Indeed, regular users of the M25 Dartford River Crossing have been able to use pre-paid tags combined with automatic vehicle identification since 1992. The result has been a significant improvement in vehicle throughflow compared with either manual or machine payment.
But the political problems currently seem insurmountable. These have led the Government reluctantly to turn its back on road pricing, and turn instead to shadow road tolls. Under this, a private developer would be paid by the Government for the level of traffic that uses a road, but will pay a penalty when roads are out of service for repair.
Even the shadow road tolling programme has hit problems, with eight consortia bidding for the supply of the technology now down to just four after the others withdrew. The remaining potential suppliers now face testing at the Transport Research Laboratory starting this summer, and then a further trial on the M3 next spring.
The bright new future of a network of privately financed toll roads no longer looks a realistic option. Toll roads might even be seen as a metaphor for the Private Finance Initiative as a whole. Private capital is being brought in, but not on the Government's original terms, and in much smaller sums than had been envisaged.