Would a 60mph Speed Limit Cut Pollution?

The speed limit on sections of four different motorways across England has been reduced for a trial period in order to try and curb the emissions caused by road transport. Effective from last month, the new speed limit of 60mph (instead of 70mph) will be in place 24 hours a day for a 12-month period, after which time the regulating body will evaluate the results.

The measure is just one of several being considered by Highways England and the Department for Transport as they look to comply with the government’s request to measure and manage the nitrogen oxide (NOx) emissions produced from vehicular transport. Nitrogen dioxide (NO2) in particular is a harmful contaminant which causes severe respiratory ailments and contributes to global warming.

Life in the slow lane

The four stretches of motorway which will be affected by the new legislation are found on the M1 between junctions 33 and 34 (by Rotherham), the M5 between junctions 1 and 2 (by Oldbury), the M6 between junctions 6 and 7 (by Witton) and the M602 between junctions 1 and 3 (by Eccles). Each stretch of road is under five miles long.

The trial will be in place for a year and will be operational 24 hours a day, as Highways England gather data about how the limit affects tailpipe emissions from vehicles travelling on the thoroughfares. The new rules will not affect HGVs, buses or other large commercial vehicles, since they must already observe a maximum speed limit of 56mph.

A deadly pollutant

The chief contaminant being targeted by the new limits is NO2, which the government believes can be reduced by bringing down the speed limit. Highways England have reiterated their belief that significant improvements will only be seen once the automotive industry addresses the problem head on and cuts off tailpipe emissions at their source, but the trial is expected to provide qualitative evidence over whether such a limit can offer tangible benefits.

NO2 is a deadly toxin that aggravates the lungs and airways inside the human body. It has been indirectly linked to the premature deaths of around 40,000 Britons each year, making it a priority for the government’s campaign. Although it is not a greenhouse gas itself, it is instrumental in the creation of ozone which acts as one of the chief contributors to global warming and climate change.

A raft of measures

The government has repeatedly signalled its commitment to addressing the UK’s rampant air quality problem and reducing the motorway speed limit is just one of many initiatives aimed at improving air quality and reducing transport-related pollution that are being considered.

For example, it has already pledged to phase out the sale of all new petrol and diesel vehicles by 2040 at the latest and has indicated it is willing to listen to the concerns voiced by environmentalists who believe that date should be brought forward by at least five years. Furthermore, it has also recently expressed consideration of including hybrid vehicles in that ban, something which had not been on the agenda until this year.