Petition: 30 km/h (20 mp/h) urban speed limit

[Dan B]

Have you not heard of the caterpillar effect ?

Are you turning into a beautiful butterfly?

 

[Linford]

Are you turning into a beautiful butterfly?

Nope, it is where the traffic joins the jam at the back quicker than the traffic at the front leaves it. This can be caused by the weight of the traffic, a bottleneck on it, or by reducing the capacity of the road by choking it with a lower speed limit.

 

[Dan B]

This can be caused by the weight of the traffic

Sounds like another argument against the 4x4 ...

 

[400bhp]

You're using one phenomena to try and disprove another... There's loads of science and maths behind both, but its generally proven that lower speed limits at busier times improve traffic flow. These facts are proven in the manifestation of the successful enforceable variable and average speed limits, such as the M42 and M25 Heathrow. Both of which I have been through many many times, and never been held up.

If you Google you'll probably find the work behind it.

Ive just finished reading this thread. Please can someone move this to the second post and entitle it "in summary"

 

[Linford]

You're using one phenomena to try and disprove another... There's loads of science and maths behind both, but its generally proven that lower speed limits at busier times improve traffic flow. These facts are proven in the manifestation of the successful enforceable variable and average speed limits, such as the M42 and M25 Heathrow. Both of which I have been through many many times, and never been held up.

If you Google you'll probably find the work behind it.

I wouldn't disagree with this, but there is an optimum for average flows, and most places outside the big cities only experience peak congestion for 1/2-1 hour per day, and if the traffic is that heavy it goes to 0mph irrespective of what limit is in place.
Have you ever seen a 20mph limit enforced to keep traffic moving anywhere ?

 

[Canrider]

I wouldn't disagree with this, but there is an optimum for average flows, and most places outside the big cities only experience peak congestion for 1/2-1 hour per day, and if the traffic is that heavy it goes to 0mph irrespective of what limit is in place.
Have you ever seen a 20mph limit enforced to keep traffic moving anywhere ?

I've been on plenty of A-road single carriageways where if everyone keeps rolling at a steady 20mph, everyone gets where they're going much faster than if people start screaming right up to the car in front, then jumping on the brakes, rinse, and repeat.
But you'll have noticed you've changed your tune from '20 zones cause congestion' to 'When does this really happen, anyways?'

 

[Linford]

I've been on plenty of A-road single carriageways where if everyone keeps rolling at a steady 20mph, everyone gets where they're going much faster than if people start screaming right up to the car in front, then jumping on the brakes, rinse, and repeat.
But you'll have noticed you've changed your tune from '20 zones cause congestion' to 'When does this really happen, anyways?'

From my own experiences, I see lower speeds making for more hassle integrating into traffic flows, and that is what I was intimating at. Is that is your interpretation of congestion ?

 

[DRHysted]

I have the perfect solution.

We make a person walk in front off all motor vehicles with a red flag. This should stop all accidents.

 

[Jimmy Doug]

First of all, obviously 20 mph will slow down traffic - that's the point! As for the argument that it makes life harder in villages because it takes longer for traffic to pull out - what bunk! The reason why this happens currently (if it happens at all) is obvious to anyone who thinks about it: as people generally expect cars to be travelling at 30 mph (or faster) they're not confident about the speed of oncoming vehicles; if everyone travelled slower, the longer 'wait' for the cars to go past would be compensated for by the fact that the rate at which the vehicles arrive would be slower, meaning that the safe distance to pull out would be reduced. As for the argument that life on the M8 would be harder at 20 mph, grow up! Obviously, the rule doesn't refer to motorways! Although the question about whether it's right to have motorways in the centre of town is another matter.
Some of the comments show why it'll be difficult to change to speed limit. Even on a bicycle forum, some people can't accept that anything touch the sacrilegious motor vehicle. So it'll make it slower to get from A to B in a car; it'll maybe 'choke' traffic. But when you consider that according to official statistics in the GB for 2010, 20% of all journeys in the car were less than 1 mile, that only 2% of trips of less than 5 miles were made by bicycle, that 20% of people say they took walks of 20 minutes or less only once a year and that 60% of adults are overweight - I say SO WHAT if car journeys in town become harder? Maybe that way people will start to think beyond their bonnet? Maybe, just maybe, people will start to become a little more intelligent: use the bus, use the bike, walk like they used to for God's sake. And when that happens not only will it be easier to walk and cycle in town, it'll also be easier and safer for those who really need their cars (the elderly, the handicapped ...) to drive.
The point is that when pedestrians and cars share the same space, 30 mph is too fast. On my residential road the speed limit is 30 mph. If a child - or an adult for that matter - is hit at that speed there's a very good chance they won't survive; reduce the speed limit by 10 mph, they probably will. And don't anyone dare tell me that children shouldn't be playing outside!

 

[Linford]

But that's bulls***. As I've pointed out, the evidence is that it is easier to pull out when there are lower speeds and that junctions work more efficiently. All you've done is repeat anecdata and try and rewrite the laws of physics, plus throw in a few straw men.

And I say that if you slow a vehicle in motion down, it will occupy the measured distance for a longer period of time...that creates congestion, and mrp demonstrated last week that the vehicles who have right of way are disinclined to give it up when the roads are congested....which in turn makes it more difficult for vehicles to join the flows, speed the vehicles up between measured distances, and they occupy that space for a shorter period of time meaning the gaps become bigger and those joiningthe flows have more time to do so safely....come one Reg. I thought you were some sort of super brain.

 

[Linford]

You should get out of Cheltenham more often.

Join the epic Mancunian jams every morning and evening....no thanks. I live in the town, I work in the countryside. My commute is against the flow of traffic, and done thankfully when it is reasonably light. If I go in later, it can be a real pain with the weight of the slow moving traffic and reduces everything to a crawl (due to sets of lights clogging junctions). You can keep your rat race ta. I can't wait for the summer and back onto 2 wheels

 

[Linford]

I didn't read past this first bit, on account of it being totally wrong.

Prove it

 

[Linford]

Post #73

That isn't proof, just the assertion of some random bloke on the internet

 

[Linford]

In terms of comparative randomness.... my moneys on the clever bloke

Nope, that doesn't cut it. try harder

 

[Linford]

I beg to differ

All he has done is say that there have been many studies done which supports his world view...he hasn't listed them yet so I say put up or shut up. My arguement is based o logic, and personal observation....call it anecdotal but that is 1st hand experience, and that is still worth a lot more than 'i read an article once which said'..........