Question to the Department for Transport:

To ask the Secretary of State for Transport, pursuant to the Answer on 16 October 2023 to Question 199996 on Motorways: Speed Limits, on what (a) basis and (b) authority National Highways conducted a trial without scientific advice to support a trial being beneficial to the environment and in reducing emissions.

National Highways have a legal duty to achieve compliance of NO₂ levels on their roads in the shortest possible time. Part of this duty was to review new technology and research.

The speed trial was one of these pieces of research undertaken by experts from Connected Places Catapult, supported by consultation and joint working with leading experts in emission measurements and modelling at TNO in the Netherlands between May 2017 and January 2019, and TU Graz in Austria.

Findings of National Highways’ research have been presented to the Dispersion Modellers User Group (DMUG) and ITS(UK) Smart Environment Interest Group and is published on National Highways’ website.

The speed trial implemented in 2021 was a way to understand if this research would work in real world conditions. The complex analysis of all the data collected on the M1 trial is currently being analysed and a report on the conclusions of the M1 speed trial will be published shortly.