As part of its ongoing programme of transport improvement, the UK Secretary of State for Transport set up a Committee to investigate the feasibility of options for road charging in the UK as a potential approach to addressing this increasing problem. In July 2004, the Road Pricing Feasibility Study Report was published. The report indicated that "the key to a fully national road pricing scheme is a technology which can charge by time, distance and place to target the costs, including environmental costs." The requirements to charge in the manner envisaged will make particular demands on the capabilities of equipment installed in vehicles, the back office processes to manage the data collected, and for policy maker to ensure that the revenues are directed into areas that the public believes are for the greater good. The on-board units (OBU) in the Swiss and German road pricing schemes represent some of the most advanced devices available in modest volumes today, and typically costing in the order of $500, it is clear that a device that could differentiate by time place and distance would need to be even more complex, potentially much more costly at today's prices, and more difficult to engineer into a reliable and robust device. Implementation within a vehicle population of 30m, even ignoring the volume manufacture, roll-out and installation issues would represent a major investment, and for some, the only practical way forward would be for equipment to be fitted at the point of manufacture. This could be complement by other mechanisms to address the operating costs of older, unequipped vehicles. The requirements to be satisfied for a car-based distance charging OBU are outlined. Cars have odometers that are not robust and tamper proof and cannot be relied upon to deliver a true estimate of distance for charging purposes. The majority of GPS receivers available today typically provide position updates at once per second during which time the vehicle could have moved some distance away from the true location at that time. Appropriate processing can overcome this to a large degree, given the relatively modest vehicle performance even under heavy acceleration or braking. Some new GPS receivers on the market have the capability to deliver position updates at ten times per second which could offer a considerable improvement. Segment charging is the technique adopted for the German lorry charge. This typically involves capturing a number of position fixes along the motorway section and comparing these with an electronic map of the road partitioned into sections. Moving to the more complex environment of an urban location makes this much more difficult, partly due to signal propagation effects, but also because the road network is much more complex and the need to define the roads into segments for comparison with position estimates becomes trickier. This would introduce ambiguity into the route undertaken, and hence the distance travelled. For the covering abstract please see ITRD E135207.
Samenvatting