The overall cost of motorway widening was estimated at pounds 3.4bn in 1989, but because of unforeseen costs this rose to pounds 4.9bn. As more motorways were included in the programme, notably parts of the M25, the cost further increased to pounds 6bn.
That is likely to be an underestimate since 10 of the 18 completed schemes cost twice as much as planned. In one case, the M20 in Kent between junctions 5 and 8, the cost increased fourfold, from pounds 19.6m to pounds 78.2m and the scheme was five months late. According to sources involved in the scheme, the final bill may reach pounds 100m.
The NAO said that the Department of Transport had underestimated the complexity of motorway widening.
When the programme was conceived, the aim was to identify the most congested motorways and start work on them first. However, the department has not prioritised schemes properly and the NAO report says that junctions 9 to 10 on the M25 in Surrey are to be widened next year though congestion is not expected until 1997. Yet 25 schemes are not being widened until after congestion is reached.
Another major cost for some schemes was the purchase of properties which eventually were not needed. The report says 'blight costs can be a significant element of the total cost of schemes'.
The Department of Transport has estimated blight will cost pounds 309m over the next three years for the full road programme, mostly on widening schemes. Better timing by the department might reduce this, the NAO said.Reuse content