The target of the trials - thought to be the first in Europe - is the car carrying only the driver, often a commuter, one of the main causes of traffic 'gridlock' in towns and cities.
So-called 'high-occupancy vehicle' lanes are well-established in the United States, notably in Los Angeles, where they have helped to reduce traffic volumes and urban car-parking. Nottingham, one of Britain's most congested cities, hopes to reproduce that success.
The special lanes, provisionally labelled 'green routes', will be opened on one or more major commuter roads as part of a wider initiative aimed at unclogging the city.
Nottingham also wants to tempt council employees into car-sharing and car-pooling by offering them inducements: for example, the chance to 'telecommute' or work from home.
There may well be hitches; the first green route planned, on the A60 Mansfield Road to the north of the city, had to be abandoned after objections from bus companies. The A60 already has a bus lane for part of its length and bus operators said that allowing other vehicles on it could take away passengers.
The initiative will be watched with interest by other cities faced with the doubling of traffic predicted for the next two decades. Nottingham was one of the first local authorities to attempt to restrain private car use in the 1970s. On that occasion the experiment went badly wrong.
Under the so-called 'zone-and-collar' system, residents in Wollaton, a well-off suburb with one of the highest levels of car ownership in the city, had traffic lights installed at their entry points into the main road network. Buses were laid on to encourage them to 'park and ride' into the city.
The measures, although modest, produced an outcry and helped to bring about the defeat of Labour at ensuing local elections.
Labour is now back in power but with a strategy aimed at boosting alternatives to the car rather than restricting the car itself.
The county council is building a new 40-mile commuter railway - the pounds 23m Robin Hood line - linking Nottingham with Mansfield, and is planning a pounds 68m supertram system.
The city is also promoting the bicycle: it has a 20-kilometre cycle network and is one of the six founder members of the European Cities for Cyclists project.
Officials also believe that growing congestion in the Eighties has changed attitudes. Traffic in the county increased by 40 per cent between 1984 and 1990: it has the sixth-highest density of population per mile of road, and ranks just below the Home Counties in vehicle densities.
Unlike Los Angeles, where high-occupancy vehicle lanes are generally part of 10- or 12-lane freeways, the Nottingham green routes will be on narrow, usually four-lane, roads. According to Ian Chatfield, the county's district transport manager, studies show that lone drivers make up 90 per cent of morning-peak commuter traffic. 'We have already reached the same sort of car-occupancy problems as experienced in Los Angeles,' he said.
Cameras, already used in Nottingham to photograph drivers who ignore red traffic lights, may be installed to prosecute solo drivers who use the lanes.
The county plans to set a lead for other city employers by reducing its own staff journeys by car by 10 per cent a year. Employees who agree to forgo their car could be eligible for prize draws, flexitime working arrangements and permission to telecommute. Staff without cars would be guaranteed a taxi home in case of late working or family emergency.
Howard Jackson, Nottinghamshire's director of planning and economic development, said that since the failure of the zone-and-collar system in the Seventies the city had fought shy of restraint on the car.
'We are hoping we can make public transport more attractive and more successful. But if that doesn't work, and the growth in car ownership and usage goes on, we have got problems.'