I have just received a reply from the Department of Transport to my FOI request about the work that is being done on the impact of the national speed limits and possible changes there to. By coincidence, the Guardian also today published my letter on smart motorways and speed limits.
It is true that most if not all the necessary research has been carried out to show that a 50 or 60mph limit would substantially reduce carbon emissions from road transport (currently dominated by ICEs) as well as trigger a modal shift to bus/train and now, crucially, to EVs. One piece of research that might be useful is how a 50mph limit could allow the narrowing of M-way lanes to allow the hard shoulder to be retained, and change the nature of smart motorways.
The DfT point to pilots where the speed limit has been reduced to 60mph to reduce NOX. In fact Highways England has sent me research to show that NOX increases at lower speeds!? The DfT also refers to the suggestion, now dropped, that the limit should be increased to 80mph.
The encouragement to be gained from this DfT ‘blind spot’ is that this is not a case where the ministry has been looking at the role of speed and has decided to carry on with the 70mph (unenforced) limit. This is a case where the need to reduce the speed limit will become overwhelming as a means of managing the distribution and use of renewable (ie low carbon) electricity. It seems unlikely that Government will prioritise personal transport over the heating of homes with heat pumps and the manufacturing of heat pumps, EVs/batteries and houses through Modern Methods of Construction.
Making a virtue out of the necessary lowering of the speed limit the Government could take credit for reducing the burden on the NHS as accidents become fewer and less severe, families suffer less trauma, public transport becomes relatively more attractive (coaches could safely continue at 60mph plus), lessening the noise from engines and tyres, showing that no new road space would be needed as congestion would be reduced, and commuting journeys would be shortened to match the perceived increase in drive time (ie the constant time budget).