SM-ALR Monitoring: M25 Second Year Evaluation Reports (two reports)

Second year evaluation of two sections of all-lane running (ALR) on the M25 have found that both are, at the minimum, achieving their objectives of ‘maintaining safety performance’, with one section exceeding expectations.The evaluation reports focus on the time period May 2015 to April 2016.

The collision rate on the scheme between J23-27 fell by 11%. However, when adjusted to take into account the ‘national trend between periods’, the figures represents a 1% increase which the DfT describes as ‘not statistically significant’ and representing ‘no significant change’.

With regard to the second scheme (J5-7), collision rates between J5-6 fell by 27%, which equates to 18% taking into account national trends. The report says the results for the whole stretch (J5-7) were ‘similar’. The report says this reduction is ‘statistically significant’, and that the scheme is ‘exceeding its objective of maintaining safety performance’.

Both reports do however concede that further monitoring is required due to the small sample size.

In terms of traffic flow, between J23-26, average daily flows have increased in excess of 10% on all links, and at a higher rate than national trends.

On the widened ALR section between J5 and J6, flows have increased 17% clockwise and 7% anticlockwise. These increases in flow are above the national trends. J6 to J7, which has not had an increase in number of lanes, saw a 5% increase in flow which is in line with national trends.

Compliance with Red X signs for the two schemes were 96% and 94%.

The reports conclude that for both schemes ‘significant capacity improvements have been achieved, supporting efficient movement of goods and services on this key section of the SRN’. The report also says there is still spare capacity to support future growth.