Safe Speed Forums

Don't know yet. We'll see.



That's one way to limit deadlock, which is the most extreme form of contention. They can also be used (and increasingly are used) to add time penalty to driving on narrow residential streets, curbing over use, a form of contention.

Also, whatever we say about the official view of speed limits (that they are the absolute top limit, nothing more than that) they also set road speed expectations. For example, contention for a lane. When you look behind, it is hard to tell how fast a car in the next lane is nearing, because of well known parallax problems. But you can (with camera around, even more so) assume that it is not much more than 70, and use that to judge. If it was nearing at 140, you might make another judgement. The same applies all over. Delays between staged lights (which manage contention) are timed according to speed expectations, signs and warnings at roundabouts (which manage contention) are placed in accordance to stopping distances from expected speeds. Head on crash tests (which cannot happen without contention) are done at typical speeds. Road features to route traffic streams (managing contention) are designed with speed expectations in mind. Drivers are trained with typical speed scenarios. It filters through many parts of the system. Just look around you and make a list! None of these would be possible if no limits (or guidelines or whatever) at all were applied.

I’m also interested to know how SafeSpeed views this Weltanschauung?

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I stole this .sig

Read my lips... CONGESTION not contention.

Got it, Roger. Thanks. Many cars competing for the same road space (contention) causes congestion. That's it. And you are right, I think, that speed limits of one kind or another can control those things.

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I stole this .sig

I do not think that speed limits per se (or a lower travelling speed) make it any more or less likely that cars sensibly spaced (say 2 ish seconds apart) in areas where, say, two lanes merge to one (or three to two) will be able to dovetail in with one another. In fact, this is less easy at lower speeds as following distances are closed up. Accordingly I refute that speed limits affect contention.

What I was referring to was the peristaltic stop start caused by the subtle but significant over-reaction that builds up as fast motorists in one queue approach slower motorists ahead in another queue. If, say, traffic is doing 30 a couple of miles ahead, then there is a gap, and another similar density of traffic to that at 30 is bearing down on them at 70, as the leaders of the back group catch up the queue, they brake... the next few brake a bit later and harder... voila - a stationary vortex in the previously faster queue which permeates to the back of this group, ensuring everyone except the first two or three in the faster lot stop then start - turbulence.

This is what a preemptive lower speed can mitigate. If, perhaps 1 mile behind the 30mph group (controlled and communicated electronically) the speed limit is brought down inm 10 mph stages and people adhere to it (not religiously by anchoring up as if for a speed camera but by and large - lift off until they are slowed enough ... the turbulence is avoided as all concerned do the same without significantly closing up the 2-second gap.

Have I made sense or is this a complete mess? I'm tired!

Yep, that would work. Prevents the effect of flow breakdown having the dramatic effect you describe.

But..



Doh!

There seems to be some conviction amongst many motorists that if they can keep their speed up in heavy traffic, and somehow force the car ahead to keep moving by tailgating it, then the flow breakdown won't occur and they'll keep moving. Perhaps they think that if they keep trying it often enough, one day it may actually work

How would you know, a 30 mph Impact would do that sort of damage.

Impact speed & the speed the vehicle travels at, can be 2 completley differant things.

They could also be the same, if the driver has not spotted the hazard and not reacted to it.

30 MPH impact is alot harder than you think

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Steve

the original post asked if I or we had ever see a 90 mph crash?

Well I and a number of others saw a 210 mph motorcycle crash on TV during the summer when a Kawasaki rider in the Moto GP parted company with his bike on the home straight. He survived with just brusies. So speed on this occasion doesn't kill.

My advice to any emergency services employee that uses the "have you seen a fatal RTA it's not nice/ noboby should have to see this etc" is if you don't like nasy accidents perhaps a career chance is in order.

Have you seen this crash yesterday?

http://news.bbc.co.uk/2/hi/uk_news/engl ... 047511.stm

Speed kills indeed - though in this case, it was lack of speed on the tractor's part that caused the accident. Really, what on earth is a 10mph tractor doing on the A34 anyway??

The motorcyclist was in a race he didnt hit any cars.

The bus was going too fast.

Its not rocket science. He was going too fast to stop and the speed made the acident worse.

_Only an idiot could argue that in an acident you are better off going faster.

If you are going too fast you are going to have an acident, therefore if you want to get hurt or die go faster.

If you want to get hurt, or dead, or cause death or injury, then you are disturbed, and in our society should not be driving a motor car. This is why we have speed limits.

Its been said repeatedly, both here and elsewhere: speed doesn't kill, INAPPROPRIATE speek kills.

120 mph on a clear day on an empty motorway in a well maintained car is perfectly safe. 20 mph in front of a school when the kids are heading home may be reckless beyond belief. A tractor travelling at 10 mph on an "A" road is potentially lethal.

Simply chanting the braindead government mantra "speed kills" ignores the other causative factors that are at the heart of accidents: inattentiveness, lack of concentration, poor driver education, badly maintained cars, aggressive behaviour and all the rest of the human foibles that make accidents inevitable.

In the United States where the maximum speed limit is still 55 mph in many states, they have an traffic accident death rate far higher than ours.

Tractors don't travel at 10 mph. That was a modern (insert spitting noise) John (insert another spitting noise) Deere. It would have been traveling at 25 mph (and speeding at that). If it was one with the new funky IVT it would have been doing nearer 35 mph.

Mr tractor driver is perfectly within his rights to drive along a dual carrageway at 20 mph as long has he has an amber rotating becon more than 4 feet from the ground.

The probable reason the bus had such a close inspection of the rear linkage was he didn't realise the tractor was going so slow.

Or on the other hand, the tractor was going too slow. If the tractor had been travelling at 50 mph, the crash would not have happened.

Besides which, the coach was travelling within the speed limit, so all the speed cameras in the world wouldn't have helped.

As Ryujin says, it's inappropriate speed that kills -- and that's something that needs driver education to improve. Short of reducing all speed limits to 20 mph, there's nothing that speed cameras can do to stop it.

Where in the report did it say the bus was speeding? Where in the report was it even suggested the bus MIGHT have been speeding?

According to the "speed kills" manifesto we all need to drive at or below the speed limit or we are dangerous lunatics in need of severe penalties. The driver of the bus was doing EXACTLY what "speed kills" is telling us to do.

I am not saying that the driver was not in any way responsible as he may have been inattentive and not noticed the tractor but to say "he was going too fast" is patently ridiculous.

If a vehicle is travelling at 10mph and a pedestrian jumps in front of you are you "going too fast to stop and speed made the acident worse"? (spelling intentional as it is a quote from speed safe)

"speed kills" HE WAS DRIVING LEGALLY so stop spouting total crap and get a life!

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Ross

Yes I'm a hoon, but only on the track!!!!

On the road where the coach / tractor crash took place the speed limit for coaches is 60mph.

Coaches are fitted with 60mph speed limiters.

We know for a (virtually certain) fact that the coach wasn't speeding.

Crashes like this one are almost all caused by driver inattention.

It's at least possible that the coach driver would have been considerably more attentive if he had control over his own speed. It's also possible that the driver would have been more attentive at a higher speed.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

It is right for him to throw mud over the road, causing death to motorists behind him.

Tractors, belong in a field, not on our roads.

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Steve

Maybe if your bus was doing 90 it would never have had a crash ever.

Maybe if all buses had their pedal stuck down, and flew around at a ton, nothing would ever happen.

Trying to avoid the argument will not win it.

Lets try it this way.

If a bus is travelling at 150mph you would (hopefully) say its travelling too fast.

If its doing a straight ton, well its better but still likely to have a nasty accident.

Drop the speed down to 50 and its less likely again, and maybe some of the passengers will survive.

Speed kills

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Exactly how is a tractor meant to get from A to B without using the road, helicopter?

My tractor for instance has a valid tax disc, it's insured, it's spotlessly clean, every thing works and so as far as I can tell I'm perfectly entitled to use the road.

If you eat, you need tractors. Sure we drag some mud out on to the road now and then. Many farmers now are hauling across fields to minimise mud on the road, but this does terrible things to your soil structure.

I understand construction equiptment uses the road too and they are even slower than we are and drag just as much mud on to the road. When the new A130 was opened about 2 years ago some one in a scaffolding truck ran int the back of a JCB 3CX. Should diggers be banned from the road? You live in a house don't you? What about cranes, they're slow? Oversized loads?

I was disappointed to see the "ban tractors" post as I felt sure it would bring the sort of reply it did.

However, I believe there is a case for a code of practice where movement of plant - including tractors - should voluntarily be restricted to non-rush-hour.

In practice I think by far and away the majority of such movement is so restricted - voluntarily.

codes of practise are fine and dandy when you work in an office and the weather doesn't matter.

I don't like taking kit down the road and try to avoid rush hour. But This is a seasonal job. Crops don't care what time of day it is, they need tending. If it's harvest time, it's harvest time and you've got to run no matter what or you might as well burn the stuff (not allowed to do that either). It's the same with all the other operations we do, there is a very narrow window of opportunity which gets narrower with the weather.

there are less and less people working on farms now and the job is getting more and more skilled. If you sit in any modern farm tractor it makes BMW's iDrive look dated. You can't have muppets driving this complex kit anymore.

Understood - and agreed - and that is why I was careful to say code of practice instead of law - and why I included "where practicable". In the case in point you mention, one day, lots to do etc, hardly practical.

Oops - EDIT - I didn't include "where practicable" but I meant to