asked the Minister of Transport what was the difference between road costs and tax revenue for a 4-axle 32-ton articulated vehicle in the year 1977-78 based on (a) road expenditure and vehicle taxation as estimated in the annex to the transport policy White Paper 1977 and (b) the actual road expenditure and vehicle taxation in 1977–78.
To smooth out variations in road expenditure for the purposes of track cost allocations, it is the practice to use the average of three years' expenditure. When the relevant estimates were prepared for the 1977 transport policy White Paper, 1977–78 was the last of the relevant three years. Had forecast expenditure for that year alone been used, the difference between the allocated costs and revenue for the 4-axle 32-ton articulated vehicle would have been £400 compared with the £900 quoted in the 1977 White Paper. Actual expenditure for 1977–78 has proved to be lower than was estimated, and if that figure were used in a restrospective recalculation for 1977–78 the deficit on this vehicle would work out at less than £400. But there are other factors relevant to the size of deficit (for example, vehicle populations, average mileages, vehicle load factors, changed patterns of road expenditure) and a complete and comparable calculation would require a major exercise.The outturn expenditure figure for 1977–78 has of course been taken into account in determining the three-year average of expenditure for the latest track cost calculations (1979–80). I am sending a copy of these to my hon. Friend.