Polluting Motorway Speed limit may be cut to 60mph

[SquareDaff]

Btw: to clarify - I don't disagree with you that in theory setting a speed limit close to an engines percieved max efficient speed would potentially reduce emissions. I do wonder what effect it would have in reality though. Pollution would, no doubt, be reduced but to what extent? I don't know. Will be interesting to see the results if they're ever published.

And also to clarify again, the original comment was lighthearted.

 

[Dan B]

I'm quite sure it's not beyond the talents of car manufacturers to design their vehicles such that they return maximum efficiency at lower speeds than they do currently, and that if they did so, the efficiency would be higher, because (as posted above) air resistance

This doesn't fix anything for already existing vehicles, of course, but why perpetuate the problem?

 

[Linford]

This started out as a reasonably relevant thread about the effects of speed limits on air pollution, since I, as a cyclist, am interested in air quality, but seems to have degenerated into a pantomime type argument fueled by a jar of marmite.

However, does anyone know the reason why this particular section of motorway has been selected, rather than a blanket reduction?

Here, there are very few motorways, even though the travel distances are far greater than the UK. Almost all intercity journeys take place on dual carriageways, where the speed limit is 90 km/hr. This doesn't seem to have harmed Turkey's economy.

Funny you say that as I am also a cyclist. Get a bus or HGV belching soot as they drive past when on my cycle, and I'm gasping for breath. I don't get that feeling with passing cars or motorbikes.
However, how you can see relevance in what you experience in the town in terms of air pollution, and how dropping the speed limits from 70 to 60 on a road you are not legally allowed to ride on is beyond me....even more so because this limit will not make a scrap of difference to the speeds which these large vehicles travel at as they are already speed limited.
The difference it will make (and I've seen this a few times in the states) is where these articulated lorries and buses actually start overtaking all the other vehicles, and they will then create a road train of lorries which spend a lot more time crawling past the other vehicles in the middle lane...in a smaller vehicle, it is a very disconcerting feeling having them overtaking or level pegging all the time...when you see the huge wheels on 3 axles on the back of a lorry spinning quickly a couple of feet from your head and you are not legally allowed to accelerate away from them for fear of getting caught, it isn't ideal.

How about worrying about the things which actually directly concerns the lot of a cyclist on the road. It would/could be far more productive ?

 

[totallyfixed]

Unfortunately society today has spawned so many overweight couch potatoes that the only trickle of adrenaline released into their bloodstream is when they drive a car too fast. As TMN says, this amply aided and abetted by Top Gear and their ilk. Speed cameras are a joke, I believe they cause more problems than they are worth because of the constant "surging" that occurs as peeps slow down for them then immediately speed up again.
I recently [New Years Day] drove about 60 miles on the motorway in shocking conditions and saw 2 very serious accidents yet still the majority of drivers were way over the national speed limit.
Average cameras do work to an extent but I would advocate hiding all cameras and definitely lowering the top speed of cars. No problem with a 60 mph limit, quite apart from any other beneficial advantage it would also save energy in the form of oil which we currently guzzle as though it is limitless.

 

[slowmotion]

There was an interesting study of exhaust emissions in 20 mph and 30 mph speed restriction zones. Surprisingly, petrol cars produced more NOx and carbon dioxide at 20mph than at 30mph.

Here's the report...
http://www.cityoflondon.gov.uk/busi...striction-air-quality-report-2013-for-web.pdf
The summary of emissions table is on page six.

 

[SquareDaff]

An interesting study Slowmo, thanks. The conclusions (quoted below) show that it's not as simple as it sounds though. By evening-out vehicle speed, lower limits can have a positive effect, although the effects are complicated by factors like traffic calming, junctions, and pedestrian crossings, but "air quality is unlikely to be made worse" by 20mph limits. So, mixed results; more work needed.

What's said above
.
Also of interest here would be the terrain of the proposed stretch of 60mph. There are a lot of hills, therefore lots of sections of tailbacks caused by slow moving, climbing lorries and then the inevitable increases of speeds on the downhill sections by impatient motorists (and also the inevitable concertina effects caused by accelerating too aggressively and then having to brake - which then cascades back down the line of traffic). A 60mph limit would probably go some way to reducing the effect of this. In this vein I'd also be interested in seeing the effects of adding a "crawler lane" for the uphill sections. Obviously having the 2 conditions in tandem would be the best case scenario - but would the introduction of a crawler lane and the retention of the 70mph limit generate the same benefits as a reduction to a 60mph limit and no crawler lane. I don't know, but I'd be interested to see the results of any trials.

 

[Linford]

The 'problem' of lorries overtaking other lorries is a 'non-problem', I mean how much does it really hold you up? For those of us who use sat-navs you will see for yourselves that you will be lucky if it adds a whole minute to your ETA, even on a substantial journey, eg the run from Manchester to Cambridge (A14). Anyone who thinks its a problem, clearly does have a problem and perhaps does not have the patience to be safe on our roads in the first place?

I am not fussed about them 'holding me up' . My reference to the States was that when they all travel at the same speed as you (in very close proximity), you have either a choice to slow down and stay behind them, or travel at a few mph more and stay ahead of them.
In the states last timeI was there, I was cruising at 75mph on the Interstate, and had 40 tonne HGV's overtaking at 80+mph on the inside, the outside, on any other lane you choose to be in, they come along side you. Bring all the traffic to 60mph, and it becomes a horrible place to be when driving a normal sized car...or motorbike

If they do introduce these lower limits, they should deregulate the motorway stretches to Dual carriageway status so the speeds of the large commercials is forced to drop to 50mph max to maintain the difference.

 

[Linford]

Theres a simpler solution for that....

MTFU

I'll remind you of that if I ever hear you bleating about drivers of cars intimidating you when you are on your cycle mister....

 

[Linford]

[QUOTE 2863560, member: 45"]Policy shouldn't be based on perceived and irrational fear, but evidence-based assessment.

Budge up a bit Smeggers and pass us your lighter....[/quote]

I'm sure you will also feel that way next time someone decides to make a punishment pass because you held them up for 10 seconds....you'll let us know how it feels won't you....but hey, it will be OK as long as they don't actually knock you off !

 

[Linford]

After you've been cycling a while you get used to it, it stops bothering you so much...

Bear with it Linfy. You will get braver. Trust me.

My colleague got rear ended a few months ago....he now has a new found respect/fear for overtaking vehicles...he has been cycle commuting 25 miles every day for the last 6 years. He had a bit of a cavalier attitude before then though quoting all the stats I see here about how safe it is on a cycle....real life experiences trump any survey you might want to spew forth....you get out on your bike enough and you will eventually get caught by something or another.

 

[Linford]

[QUOTE 2863615, member: 45"]Rear-ended by an overtaking vehicle?[/quote]

http://www.cyclechat.net/threads/colleague-just-rear-ended-on-his-e-bike.141845/

 

[Linford]

[QUOTE 2863640, member: 45"]Yes I remember. He wasn't overtaking.[/quote]

Either not giving enough room or just not seeing a cyclist...the result would have been the same...you sound like you are championing bad driving standards whichever way I look at it.....

 

[Linford]

Why not have the crawler lane and the 60 mph limit?

Or force the HGVs and buses to stay below 50mph...where they wil be a lot less polluting than when bouncing off their limiters

 

[SquareDaff]

Why not have the crawler lane and the 60 mph limit?

I did put that would be the best scenario (IMO) - the scientist in me would be interested to see if "smoothing out" traffic flow would have as much effect as lowering the max speed limit by 10mph. I don't know and as far as I know (and I'm willing to be corrected) no previous studies have been made.

 

[Linford]

[QUOTE 2863865, member: 45"]No. You're claiming that reduced speed limits on motorways are bad because of a perceived fear which might be felt by some when a large vehicle is in a lane alongside. To evidence this fear you give an example of a cyclist being rear-ended in a lane.

If you're frightened when a truck is alongside you on the motorway then this doesn't mean that the truck is driving badly, it just means that you're allowing a perceived but not real fear to affect you.

Ya dar make nar sense.[/quote]

There is a saying.. 'If others around you are losing their head, whilst you remain calm, perhaps you haven't grasped the seriousness of the situation' ...i would suggest that you might not see the dangers clearly through those rose tinted specs.

These large vehicles are a risk to all other vehcile users..be that cyclists, motorcyclists, and car drivers. On the motorway, they insist on tailgating each other 5 or 10 ft apart....this is even worse when they overtake other slower moving HGV's

My 4x4 cruises best on the motorway at about 55. This means that I mix a lot with them, and appreciate well the issues when level pegging with these large vehicles. In the bad weather, they throw up huge amounts of road spray which for other hgvs isn't really a problem due to the cab height. However If you cannot get away from them and are in a small car, you really do feel you are at their mercy, struggle to edge away from them, and when this road spray is all over you, can severely limit your visibility.
To bundle all vehciles on the motorways at the same speed it a bad idea.