Time, Distance, Position Road Pricing

There is significant experience, both internationally and in the UK, of road charging schemes.

They fall into three main types: charges for crossing a cordon; for driving in an area (e.g. the London Congestion Charge) and charging for the use of a linear section of infrastructure such as a bridge or motorway. They use technologies such as toll booths, self-declaration, microwave tags and automatic number plate recognition. These are well proven, but limited in scale.

As demand management tools they are effective at dealing with city centres (the London charge has cut congestion in the charged area by an average of 30 per cent), but cannot deal with large complex urban areas without a large number of boundaries with infrastructure at each one. And they can be blunt. They do not distinguish between short and long journeys, or several journeys in a zone.

The UK government feels that a fully national road pricing scheme requires a technology which can charge by time, distance and position (TDP) to target the costs, including environmental costs.

In such as scheme, vehicles would be fitted with a "black box" or on-board unit (OBU) which could work out exactly where, when and over what distance the vehicle was being used. Tarriffs would vary depending on the road being used and the time of day. Feedback from the OBU to the motorist, it is hoped, would change driver behaviour and spread journeys out, away from roads suffering from peak-time congestion.