The Government has announced plans to bribe the public into taking part in road-pricing experiments aimed at reducing traffic congestion.

Rather than forcing drivers to install a black box to track their cars’ movements, ministers hope to encourage volunteers by making the system financially attractive. The Times reports that ministers were taken by surprise by the strength of feeling against road-pricing plans.

The Department for Transport plans to develop a system where drivers will be offered a choice: carry on paying motoring taxes or switch to a road-pricing meter in the car that could save money. But drivers could be offered a discount on fuel duty in return for agreeing to pay a distance-based charge, which would vary according to the level of congestion.

The department hopes to test the voluntary approach in regional pilot schemes due to be announced this year. Manchester, Birmingham and Cambridge are being considered for the experiments.

The hope is that positive reports from volunteers will help to silence suspicions about the concept, including concerns that the black box will be used to spy on drivers’ movements and to raise the overall amount paid in motoring taxes.

An American road pricing experiment in Seattle found that almost 80% of volunteers made fewer car journeys on congested roads when offered a financial reward.