The Active Traffic Management (ATM) project on the M42 near the City of Birmingham was the first pilot project in the United Kingdom (UK) to dynamically use the hard shoulder together with variable mandatory speed limits during periods of peak demand. When ATM was first introduced in 2006, the maximum permitted speed limit during hard shoulder running was 50 mph (HSR50). However, in March 2008 a new algorithm was introduced which increasedthe maximum allowed speed limit to 60 mph during hard shoulder running (HSR60). As a first trial, HSR60 was implemented on one link, junctions 4 to3A [J4-J3A] with the plan to roll it out on other links of the M42-ATM section. The impact of HSR60 on traffic operation over the link between [J4-J3A] was assessed against HSR50 over a period of six weeks. The results have shown that HSR60 reduced the average journey time by 8% and increased the speed by an average of 5.4 mph. However, no evidence was found to suggest that HSR60 increases throughput when compared with HSR50.
Samenvatting