Safe Speed Forums

Now I'm a right one for carrying on about how folks do, by and large, drive far too close to the vehicle in front particularly on motorways. But I'm beginning to wonder if those chevron things they paint on the road and accompany with the instruction to keep two apart aren't more trouble than they are worth.
Travelling down the M6 from Liverpool today the warnings of congestion ahead apeared on the overhead signs and, sure enough, we slowed to a crawl a couple of miles before the chevrons begin. This is a quite normal experience on this stretch of motorway when traffic gets quite heavy.
I reckon that as traffic approaching the chevrons attempts to establish a more appropriate gap to the vehicle in front, they ease off the gas causing a cascade of slowing to pulse back down the motorway. Result - congestion.
Thus these chevrons, whilst a well meaning attempt to remind drivers how big a gap they should be leaving at all times (not just in the chevroned area ), in effect upset the fine balance of traffic flow and cause congestion.

They would help if they were painted 1 seconds apart. The ones I checked were 2 seconds apart inviting you to leave a 4 second gap.

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Speed limit sign radio interview. TV Snap Unhappy
“It has never been the rule in this country – I hope it never will be - that suspected criminal offences must automatically be the subject of prosecution” He added that there should be a prosecution: “wherever it appears that the offence or the circumstances of its commission is or are of such a character that a prosecution in respect thereof is required in the public interest”
This approach has been endorsed by Attorney General ever since 1951. CPS Code

As RigPig was going south today , I must have been going north and noted the same thing. These chevrons commonly cause tailbacks on this section, and whilst they are a bit of a menace, I have to say that with hundreds of people (idiots??) in Lanes 2 & 3 literally 5 feet from each other's bumper, there is an accident there waiting to happen, and it ain't the chevrons. When the M6 gets like this I just keep in Lane 1 and usually always have about 200 yards space in from of me.

Strange how people think they will get there quicker by tailgating.

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Good manners maketh a good motorist

If only tailgaiting cameras could be introduced, in the same (highly automated way) speed cameras operate. And i'm not talking a slight non observation of the 2 second rule here! Perhaps this would actually have an impact on road safety?

FWIW, I suspect that what these chevrons do is remind drivers of the proper, safe gap. At peak times, you can stand on a bridge over any motorway and count the number of vehicles that pass in one lane. I've done that several times and counted between forty and fifty vehicles per minute in lanes 2 and 3 and thirty or more lorries per minute in lane 1.

Two seconds separation means thirty vehicles per minute is the absolute safe maximum (and that's assuming zero vehicle length). Assuming an average vehicle length of 15 ft, gives a maximum safe capacity of 28 vehicles per minute at 70 mph, dropping to 25 vehicles per minute at 30 mph. With the separations that I've noticed, the busiest roads are carrying nearly double their maximum safe capacity - and that (IMO) is the reason for the congestion you notice.

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Will

If such a device could be introduced then there would be an outcry, just as there currently is over speed cameras. Drivers would be getting fined for something that they currently routinely do without even thinking about it - part of the problem methinks. The fact that there is a clear and obvious danger posed by tailgating, as opposed to simply driving over a given speed limit would, I believe, get lost amidst the furor the cameras would cause.
Speed cameras and road chevrons are supposed to remind drivers how they should drive; the reality is in fact a million miles removed from this as witnessed by the way people do drive.
I'm beginning to wonder if the motoring public shouldn't just be left to their own devices and to hell with the consequences

Rigpig wrote:

Like they do in Egypt as per Rogers post.

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Shooting is good for you and too good for some people.

I think the intention is that the separation gap should be the distance between two chevrons, i.e. 2 seconds. However it isn't made clear and can easily be interpreted the other way.

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"Show me someone who says that they have never exceeded a speed limit, and I'll show you a liar, or a menace." (Austin Williams - Director, Transport Research Group)

Any views expressed in this post are personal opinions and may not represent the views of Safe Speed

I don't know about that - i think the public would find it quite satisfying to know that the tailgaiter, driving 3ft from the rear bumper, with his fog lights on (in the absence of fog), driving a 15 year old BMW, with aftermarket alloy wheels and an altered exhaust note, while smoking and using a mobile phone simultaneosly at 70mph was likely to face rebuke in the form of a heafty fine/ban /points on licence.

I think it would generate a sense of justice and perhaps address the issue that exceeding a speed limit is not the cause of all crashes.

I wasn't resident in the UK when speed cameras first appeared en-masse but I would imagine that the public might have initially perceived them to be a good idea to catch those maniacs who speed through their village. Of course, many drivers now realise that those 'maniacs' are in fact just as likely to be themselves as anyone else. Indeed, much current support for speed cameras stems from the mistaken belief that they punish bad drivers.
Tailgating isn't just about having that brainless moron purposefully trying to bully you out of the way in the situation such as you describe above. Drivers mindlessly tailgate the car ahead of them with no real intent on getting them to move over. They will also tailgate because of (their own) poor lane discipline; i.e. the queue of vehicles in L3 will close up to prevent someone undertaking them all and then joining L3 as they approach to pass the obstructing vehicle in L2.
So whilst intially there might be support for tailgating cameras, once everyone begins to realise that they are tailgaters (as well as speeders) themselves as the cameras begin flashing, I predict that there would be an outcry.
The traffic system is a finely balanced mechanism which relies heavily on the willingness of drivers to co-operate and work within it. Attempts to interfere and force compliant behaviour where it currently doesn't exist appears doomed to failure. It is with respect to this one observation alone that I felt it necessary to concede that Paul Smith is actually quite right in his analysis of the effect speed cameras are having on our roads.

Just as they would get satisfaction in knowing that the boy racer who tears around the neighbourhood at 70MPH+ was likely to face rebuke in the form of a hefty fine/ban /points on licence.
But that doesn't happen, does it? What we actually get is the responsible drivers who blip over the 30 limit who get the hefty fines/bans /points on licences.
So why should we not expect the same thing wrt tailgating?
Most probably, we'll end up with people being fined for a 1.95 second gap.
And what about when someone cuts in in front of you about 2' from your front bumper, just as you pass a 'tailgating camera'?

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Only when ideology, prejudice and dogma are set aside does the truth emerge - Kepler

Especially when you get flashed for "tailgating" when someone squeezes out in front of you and you end up through no fault of your own being up against their bumper, albeit for a few seconds. That's all it takes...FLASH!

Don't forget that automatic "tailgating" detection systems will be inherently dumb and will not take circumstances into consideration...

Have you ever had somebody just change lanes into your nice safe 2 second gap - normally without indicating or accelerating up to match the speed in your lane? Well to a dumb camera system that has just made YOU the tailgater - you are too close and actually closing on the vehicle in front. Yes I know that you lifted off the throttle because you didn't want your brake lights causing panic braking behind you, but the Camera system doesn't know that, so NIP in the post offering £60 and 3 points, and photo evidence of you much too close to the vehicle in front. You could loose your licence in 3 or 4 miles on a single journey without doing a single thing wrong.

To be fair to T2006 he did try envisage a smart system that would in some way ignore transient tailgating situations.
Setting aside the technological difficulties in implementing such a systems, I mainatin that most drivers tailgate in some way that would be detected by our hypothetical 'smart' camera system and get pinged. There would be an outcry as a result.

I've said this before, but at motorway speeds in excess of around 60mph there is nothing "nice" or "safe" about a 2 second gap.

At 60mph an alert driver in a vehicle in good conditions on a dry road might just about be able to stop in time using maximum braking effort if the vehicle ahead stops dead. Any faster and 2 seconds is almost cetainly not enough.

In the real world you want a bit in hand, so that you don't have to use max braking effort (which might emabarass the tailgater behind you even if you manage to stop), and you don't have to rely on quick reactions. And of course you need to allow for less than optimal road conditions.

And vehicles do stop dead, even HGVs, if they hit someting solid. I had one do just that in front of me last year!

There is no such thing as a "smart system".

Would you trust a computer to decide if technically you were tailgating.

Remember, if there was the possibility of getting busted would there not be the temptation to hit the brakes to avoid a fine if someone pulls out and closes the gap.

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Speed camera policy Kills

This has been said many times but I'll say it again. The two seconds gap does not and is not supposed to represent your stopping distance. It is your reaction time safety margin. The vehicle ahead cannot stop instantaneously any more than you can. However, a driver should also observe much farther ahead than the vehicle immediately in front of him.

If you were seriously embarrassed by a HGV stopping suddenly when you were two seconds behind it, you were either not paying sufficient attention or using sufficient forward observation. If it stopped in a shorter distance than its braking distance under maximum braking effort (e.g. because it hit something, which btw would have to very large and solid), you should have been aware of that possibility before it happened. If you weren't, your observation was inadequate. Perhaps you should have been adjusting your road position to obtain a view around the truck? If the forward observation was really impossible to achieve, a greater gap than two seconds would be appropriate, together with a very high level of alertness for any sign of speed reduction.

The only 'fair' way of setting up tailgating cameras would be to have two cameras some distance (say 200 yards) apart, so that it could be seen if your tailgating was transient (e.g. caused by someone else's action) or constant.

The only problem is, as with speed cameras, people would get wise to them, and pull back a bit where the cameras were located.

I was speaking in the most hypothetical of ways - just becuase there aren't the capabilities now, doesn't mean there won't be in the future.

I completely agree a that a system which arbitrarily enforced minor breaches of the 2 sec rule in a robotic fashion such a gatso, would be totally unworkable and utterly counter-productive. Perhaps 10 - 20 years down the line there could be such a thing as an "intelligent" and smart enforcement system that at the moment is difficult to imagine.

Think back to 20 years ago - if you ever suggested to someone they might be able to discuss road safety with a complete stranger using a computer and something called an "internet" they probably would have laughed out loud. Now look!

Actually at the time I had a five second gap at less than 50mph and was not seriously embarassed. This was in a torrential downpour on the M1, with bad spray and poor visibility, and a wet road that probably had enough water on it for aquaplaning, so I was driving at an appropriate speed.

But the HGV ahead DID stop more or less dead, becuse it hit a large pile of wreckage that included a number of other HGVs as well as other vehicles. Seeing it stop that suddenly was an education, and I will never again claim that it can't happen.

The point is that a good number of those ahead of me WERE seriously embarrassed, probably even maintaining 2 second gaps!