Local transport schemes meet short-term aims but evidence of economic impact limited

A sample of local authority major schemes overran in cost in line with DfT expectations and were successful in reducing congestion and improving journey times.

But there was little evidence that longer-term objectives such as economic and social impacts were achieved, according to a 'meta evaluation' of 23 major schemes implemented in the five years to 2012.

The report by AECOM and Atkins found that schemes slipped by an average of 23 months and increased in cost by 52% than forecast at programme entry stage, "figures broadly in line with DfT guidance on optimism bias".

And the schemes had "evidently been successful in delivering a range of short-term objectives, particularly focused on reducing congestion and improving journey times". However, few of the scheme evaluations compared forecast impacts with actual impacts, "thus restricting the opportunity to fully understand the reasons for any variance".

The report calls for a requirement for all scheme promoters to present baseline, target and outturn data for each outcome being evaluated. It also recommends evidence from users of the schemes, so that the cause and effect of observed behaviour change can be studied.