Proposed 60 mph speed limit, Will it REALLY cut pollution? Options

[x2lls]

My view is that I don't believe it will.
Yes, a constant speed is almost always the most efficient way of using fuel, at the right speed that is, but with the high volume of vehicles on the roads, will it actually work?

I suspect all it will do is bring down the average speed of those that usually drive at 80 plus, to a slightly lower level. Does driving faster actually increase the volume of pollutants expelled? After all, the fuel is only being burnt at a faster rate at higher speed, so surely a litre burnt in say, an hour as opposed to thirty minutes will still convert to the same amount output, only over an extended period of time?

[Andy Capp]

Here you go ladies...

"One of the measures to decrease the NO2 concentration near motorways is to reduce the speed limit from 120 or 100 to 80 km/h. Its effect is well-known
in the Netherlands, since it was introduced on the A13 motorway near the Rotterdam district of Overschie in 2002, and accompanied by strict enforcement. Evaluation studies show that the reduced speed limit led to a significant decrease of NOx emissions and thus (although to a lesser degree) to lower NO2 concentrations (Droppert-Zilver & Wilmink, 2001). The strictly enforced lower speed limit also caused a more homogeneous traffic flow, and these two factors essentially caused a decrease of air pollution. Besides this improved air quality the noise level also decreased. Moreover, the measures resulted in an improved traffic flow and a higher degree of traffic safety."

http://www.google.co.uk/url?sa=t&rct=j...d2k&cad=rja

Mind you, in this example, they reduced the speed to ~50mph!

[The Optimist]

Here you go ladies...

"One of the measures to decrease the NO2 concentration near motorways is to reduce the speed limit from 120 or 100 to 80 km/h. Its effect is well-known
in the Netherlands, since it was introduced on the A13 motorway near the Rotterdam district of Overschie in 2002, and accompanied by strict enforcement. Evaluation studies show that the reduced speed limit led to a significant decrease of NOx emissions and thus (although to a lesser degree) to lower NO2 concentrations (Droppert-Zilver & Wilmink, 2001). The strictly enforced lower speed limit also caused a more homogeneous traffic flow, and these two factors essentially caused a decrease of air pollution. Besides this improved air quality the noise level also decreased. Moreover, the measures resulted in an improved traffic flow and a higher degree of traffic safety."

http://www.google.co.uk/url?sa=t&rct=j...d2k&cad=rja

Mind you, in this example, they reduced the speed to ~50mph!

Interesting paper, thanks for sharing. I will admit to being sceptical on this strategy overall, but this provides some solid data and I have no solid basis for my scepticism other than my gut feeling

I read this short article on the EEA site and it included a note on the level of emissions caused by traffic with a source cited.

http://www.eea.europa.eu/articles/reducing...ts-on-motorways

Compared to 1990, the EU has significantly reduced its total greenhouse gas (GHG) emissions, with policy and technology helping break the link between economic growth and GHG emissions in almost all sectors. The only clear exception is transport, where GHG emissions actually rose by 25 % between 1990 and 2008 in the 32 EEA member countries (these numbers exclude the international maritime and aviation sectors).

What is interesting is that it is suggested that fuel consumption (and by association, the pollutants) could drop 12-18% but the reality is it's likely only a 2-3% drop. To achieve the higher cuts, would likely require significant enforcement so as with everything in life there is a balance. Is it possible a slower speed could reduce emissions on the macro scale? Yes. Will it need more speed cameras and other measures to be achieved? Probably.

Again, this tackles things from the macro level, but I'm inclined to agree with others on this thread that the micro level should be as much a focus. I would start with an earlier suggestion of setting up special 'zones' for lorries to overtake. For me, it seems that the worst moving bottlenecks are when when one lorry slowly overtakes another. This disrupts traffic a long way back, causes other vehicles to apply brakes and generally results in a turbulent flow. Surely this creates a significant problem when all such incidents are aggregated?

Other suggestions could include more widespread use of minimum speed limits. Nothing worse than having a vehicle travelling 30 mph below the speed limit in normal conditions. I can't be the only one to have seen a lorry travelling at below 50mph on the motorway and gone past them only to see a Vauxhall Corsa with a driver that has their nose nearly pressed up against the windscreen. Then again, maybe I am

[Andy Capp]

What is interesting is that it is suggested that fuel consumption (and by association, the pollutants) could drop 12-18% but the reality is it's likely only a 2-3% drop. To achieve the higher cuts, would likely require significant enforcement so as with everything in life there is a balance. Is it possible a slower speed could reduce emissions on the macro scale? Yes. Will it need more speed cameras and other measures to be achieved? Probably.

Again, this tackles things from the macro level, but I'm inclined to agree with others on this thread that the micro level should be as much a focus. I would start with an earlier suggestion of setting up special 'zones' for lorries to overtake. For me, it seems that the worst moving bottlenecks are when when one lorry slowly overtakes another. This disrupts traffic a long way back, causes other vehicles to apply brakes and generally results in a turbulent flow. Surely this creates a significant problem when all such incidents are aggregated?

Other suggestions could include more widespread use of minimum speed limits. Nothing worse than having a vehicle travelling 30 mph below the speed limit in normal conditions. I can't be the only one to have seen a lorry travelling at below 50mph on the motorway and gone past them only to see a Vauxhall Corsa with a driver that has their nose nearly pressed up against the windscreen. Then again, maybe I am

Bear-in-mind, this isn't about reducing GHG as much as reducing pollutants that cause ill-health. The proposal, while an irritant to many, is apparently proven to reduce pollution, accidents, and improve traffic flow in areas of high traffic volumes. It is also relatively cheap to implement with average speed cameras, or even dummy average speed cameras. Perhaps also it would be useful to have variable speeds, so that when traffic builds up, the speed limit is dropped, but relaxed when traffic volume drops.

[Exhausted]

Perhaps also it would be useful to have variable speeds, so that when traffic builds up, the speed limit is dropped, but relaxed when traffic volume drops.

Would that be legally enforceable as the speed limit on a road is set by legislation for a particular stretch of road. Any changes must be advertised and then approved. Even the motorway overhead signs are an advisory speed only when they show 50mph. This does not apply in road works however as these will have been approved ahead of the work starting.

[MontyPython]

Would that be legally enforceable as the speed limit on a road is set by legislation for a particular stretch of road. Any changes must be advertised and then approved. Even the motorway overhead signs are an advisory speed only when they show 50mph. This does not apply in road works however as these will have been approved ahead of the work starting.

Wrong - where a variable speed limit is in place the overhead advertised speed is enforceable