Monitoring and evaluation of smart motorway schemes

Abstract

Smart motorway schemes aim to address congestion issues and improve journey time reliability by utilising a set of advanced Intelligent Transport Systems applications and making use of the existing road space as much as possible. The M42 Smart Motorway Pilot, introduced in September 2006 by the Highways Agency (known as Highways England since April 2015), established the concept of Hard Shoulder Running (HSR) for the first time in the UK, together with variable mandatory speed limits during periods of congestion. Following the success of the Pilot, smart motorways are being rolled-out to other sections of Highways England’s strategic road network. This research has been carried out to understand the performance of smart motorways and its limiting factors.

A review of the concept of highways capacity was carried out to understand the parameters that influence traffic conditions during smart motorway operations. This was followed by a series of analysis using empirical data which examined the performance of existing smart motorways schemes on the M42 and M6 motorways near Birmingham, UK. Overall, smart motorway schemes have significantly reduced average journey times and journey time variability, improved motorway capacity and smoothed traffic flow. The level of benefits observed varied from one scheme to another mainly due to the different site conditions (road geometry, traffic demand and patterns). However, each scheme consistently demonstrated considerable improvements when compared to non-smart motorway conditions.

One of the aims of smart motorways is to improve the distribution of traffic between lanes. Examination of the data showed that hard shoulder utilisation increased with traffic demand, however, it was potentially underutilised and influenced by the proportion of traffic leaving at the next junction. A multivariate analysis was carried out to establish a model which described motorway capacity during smart motorway operations using various traffic parameters. The findings from this research can be applied to assist in the application of smart motorways both in and outside of the UK, to reduce wasted time for commuters, business trips and freight movement.

It is recommended that the study is taken further with the newly introduced smart motorway schemes, which will include additional parameters such as local physical characteristics of the road (e.g. width, gradient, curvature) and the operation of All Lane Running.

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