Road user charging

Technology

A national congestion charging scheme covering the whole road network could be implemented using a number of different technologies. The distance travelled by a vehicle, and identification of the road network it has used, can be established by various techniques.

The most common system designs are based on the global positioning system (GPS) of position-fixing satellites. GPS supports a system that could cover all types of vehicles on all UK roads. It would have the ability to vary the charge by the individual road, the time of day, the type of vehicle and the degree of congestion. It could even detect when air quality is poor and impose a higher charge accordingly; or apply a reduced charge if the road user is in a 'green' vehicle (this has not been modelled).

Paying the charges could also be flexible. Drivers could pay using smart cards in the vehicle, or off-vehicle by direct debit or credit cards. Payments could be made on a monthly or quarterly basis, similar to electricity bills.

To make fully informed travel decisions, road users will need to know what charges they will face prior to their journeys. There must to be easy access to advance information about charges for any given journey, according to a designated route and time of day. Charging tariffs would have to be readily available electronically via the internet and other means. Charges would be calculated on the basis of expected, rather than actual congestion, so that if an incident occurred on route there would be no additional charge for congestion caused as a result.

Technology also brings additional advantages for the driver in the form of value-added services, such as route navigation, providing turn-by-turn route instructions and real-time traffic information that warn of delays. In the event of a breakdown or a minor accident, breakdown services or emergency vehicles could be given exact vehicle locations.

It is possible to use this technology to link the charge to road users and the level of service they receive: this could mean that drivers could expect a given level of service and be compensated directly if this service falls below that level.

The system of congestion charging that CfIT considered is primarily intended to make the most effective use of the road network we have at the time the system is introduced. However, the prices can also be used to give signals for changes to the system. Where demand still exceeds supply after charges are applied (ie where some congestion still exists), this suggests a demand for improved service quality, which might justify the relevant highway authority providing new road capacity - as long as the benefits of the new road exceed the costs.

A scheme that covers the whole country avoids problems arising from boundaries between areas covered by congestion charging and those that are not. There would be no point in vehicles diverting from roads where charges were in operation to avoid charges. Charges could be adjusted so that traffic would only switch between roads, or between times of the day, where it was in society's overall interest for it to do so. In addition, the pattern of road charges, reflecting true 'costs of use' of different roads, would give better information on the location of new developments and facilities, such as supermarkets.

To realise the benefits from improved traffic flow on all roads, a variable charging scheme would need flexible technology that could operate across the whole UK road network.

CfIT - Paying for road use: www.cfit.gov.uk/docs/2002/pfru/index.htm