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New 30 mph speed limit on M8

A Scottish Greens motion to cut the speed limit on the city-centre section of the M8 to 30 mph was passed by Glasgow City Council.

A motion to reduce the speed limit from 50 to 30 MPH for the city section of the M8 motorway has been passed by Glasgow City Council. Photo credit – Derek Lewis.

The proposition tabled by Scottish Greens Councillor Christy Mearns, was described as 'madness' by the Scottish Conservatives, who have also warned that the move will have a detrimental impact on Glasgow’s economy.

The Scottish Conservatives argue such a move will "likely damage the city's economy and the jobs, which people in our city rely on."

Graham Simpson MSP, Scottish Conservative Shadow Transport Minister, has denounced the move as part of the Scottish Greens’ "anti-motorist agenda.”

However, Councillor Mearns believes the radical move could help "lower air pollution and design a city fit for the future.”

The move reflects a growing European trend amongst authorities seeking to reduce motorway speed limits to reduce carbon emissions.

Opponents argue that reducing the speed limit to 30 mph might actually increase pollution. Photo Credit – Derek Lewis.

The Netherlands introduced a 100km/h speed limit during daylight hours as far back as 2019. Some regions in Austria have also introduced a 100km/h limit, and plans are in the pipeline to roll this out nationwide in the near future.

Germany could soon follow. The country’s environmental agency released a study in January that found that lowering the speed limit on the autobahn to 120km/h could reduce carbon emissions by 2.9%.

However, speaking to Radio Clyde News on Twitter, motoring journalist Maggie Barry said that reducing the speed limit to 30 MPH might actually increase the harmful effects of vehicle emissions, "When you have a stop-start situation, that's when emissions build up and you begin to have problems."

Stewart Andrews, a car mechanic from Ardrossan, North Ayrshire, uses the city stretch of the M8 on a daily basis as part of a break-down service he provides. Mr. Andrews informed that traffic there at certain times of the day is down to a crawl and that reducing the speed limit to 30 miles per hour will cause even more congestion and lead to increased pollution.

Car Mechanic believes a reduced speed limit will increase pollution. Photo credit - Derek Lewis.

“If congestion increases, this means more engines idling. Idling engines are burning fuel without going anywhere, costing drivers more money. Idling vehicles also produce pollution like poisonous chemicals, gases, and soot, so, if you get a lot of vehicles idling in the same place at the same time that means lots of pollution. I think if this policy goes through it will be a disaster.”

Mr. Andrews’ claim that a reduction in the speed limit will lead to increased pollution is given further credibility by the results of tests carried out by Argonne National Laboratory. Findings from these tests concluded that an engine left idling for more than 10 seconds uses more fuel and emits more C02 than restarting that same engine.

Idling for more than 10 seconds uses more fuel and emits more CO2 than engine restarting. Data courtesy of Argonne National Laboratory.

The shaded area beneath the blue line is the Idling fuel rate; the red line (restart)before the engine is restarted (at 10.1 s) represents the quantity of fuel that the engine would have burned if it were idling instead of being off. The shaded area between the lines after the engine is restarted represents the excess on restart.

Rush hour M8 Friday

This view contrasts with the opinion of Dr. Giulio Mattioli, transport scientist at the Technical University Dortmund. Speaking to Euronews, Dr. Mattioli stated, “If you reduce [the speed limit], you will not just have slower speeds for many vehicles, you will also have a more regular flow and less congestion, and then that might actually increase the average speed.”

Dr. Mattioli conceded that “We cannot think that we will solve the transport emissions problem purely through speed limits, as we will not solve it purely through electric vehicles, or we will not solve it purely through better public transport. We will need to do all of those things at once and even some more in order to achieve emission reductions.”

Glasgow City Council Convener for Transport, Angus Millar (SNP) has contacted Transport Scotland to request that the reduced speed limit be considered for implementation on a six-month trial basis. Transport Scotland was contacted regarding the proposal but chose to make no comment.

M8 Photo Gallery


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