In 2006, the M42 J3a-7 section was the first smart motorway in the UK to make use of the hard shoulder as an additional lane at peak times. It was comprehensively monitored and evaluated over its first 3 years of operation.

The results of this evaluation were documented in published reports setting out the performance against all these criteria. As one year is not sufficient to conclusively evaluate safety performance, this was evaluated again after 3 years of operation.

1. Overall, journey times decreased between an average of 24% (northbound) and 9% (southbound). This equates to a statistically significant reduction in journey times of approximately 4 minutes (northbound) and 1 minute (southbound). 1-year report.
2. Overall there was a reduction in the number of personal injury accidents and the severity of accidents during the first 36 months of operation (from average 5.08 accidents per month to average 3.17 accidents per month). 3-year report.
3. Most vehicle emissions reduced by between 4 and 10 percent. Fuel consumption also reduced by 4%. 1-year report.
4. Compliance to variable mandatory speed limits on the main carriageway at least 94% or better at 70mph, 60mph and 50mph and 84% or better at 40mph. Speed compliance on the hard shoulder was on average 97% or better at 50mph and 93% or better at 40 mph. 1-year report

The success of this original pilot scheme on the M42 provided the foundation for the roll out of smart motorways.

Smart motorways provide a more efficient way of increasing capacity on the roads than traditional widening and have successfully reduced congestion and improved journey time reliability.