Safe Speed Forums

One of our employees, a young lady ~20 years old, was involved in a rather nasty motorway smash last week. She was not seriously injured (I think some whiplash or back trauma) but it could easily have been a lot worse. AIUI, she was driving in L1 of the M25 (not sure of her pre-impact speed), the car ahead of her braked unexpectedly, she went into the back of it and was then hit up the chuff by the car hehind her, pushing her into L2 where a LGV hit her. Her car was written off - not sure about damage to the others.

This is a typical motorway scenario, several cars in line all driving too close to allow adequate safety margin/time to react. A lot of motorway crashes with these components are damage only shunts. This one could easily have been fatal. I don't know if our employee will be able to learn from this (there will be a tendency to blame the crash on the car ahead for braking/stopping unexpectedly) but I hope she can.

This strengthens my conviction that road safety messages aimed at reducing the incidence of inadequate following distances could do more for road safety (and congestion) than any other simple measure.

One thing it does point up is how inherently safe the principle of separate carriageways is though.

Imagine if the same shunt had pitched her right one lane and then she'd been struck by an oncoming LGV?

[edited to add]
Totally agree with your thoughts of course.

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There should be far more ads around about stopping distances (and should also hammer home the fact that you'd be held liable for running into the back of someone). The only one I've seen is some unofficial ad from the RAC.

However, even when the stopping distances are marked out, most drivers still seem to fail to keep correct distances. Take the westbound section of the M62 between Leeds and Manchester where there are chevrons painted out on the road accompanied by the sign 'Keep apart 2 chevrons'. It seems the majority of drivers along here don't even keep one chevron apart.

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Why can't we just use Common Sense?

I've spawned a 'Brainstorming' topic from this: http://www.safespeed.org.uk/forum/viewtopic.php?t=7153

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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 doesn't particularly help when Top Gear shows Mr Clarkson complaining that a van driver was causing congestion by leaving too big a gap. Cue mindless idiots thinking they're doing the world a favour by tailgating (as long as they're not speeding, of course).

The inherent problem on the M25 is that if you do leave sufficient stopping distance it is normally pretty quickly occupied by another vehicle.

I am not sure what the solution is but I am more and more forming the opinion that changing the law on undertaking is the correct starting point.

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Former Military Police Officer and accident investigator

I was shouting at the TV for that one. It reduced my (already pretty low) oppinion of Mr. Clarkson. He's a good presenter and he makes me laugh, but it seems he knows bugger all about driving properly.

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Science won over religion when they started installing lightning rods on churches.

sometimes it's hard to tell if it's that or if he's just deliberately trying to stir people up.
One thing all those shows do need to address though is the presenter talking to the camera (and presumably trying to remember the script) while driving on public roads. Not exactly the safest thing to be doing. Also TG often shows footage of their guys plonking along in L3 with a queue of traffic behind them as they blindly prattle on about something.

You say that (and other people do as well) but that's not what I actually find. I drive J16 - J10 and back every working day and very rarely experience this problem. Perhaps it's just attitude. I regard the space I leave as being an open invitation to anyone else to use if they wish. [edited to add]On the rare occasions it is used, I simply adjust throttle pressure momentarily to re-create it.

Define "2 chevrons apart".

Is it always at least two chevrons visible between you and the car ahead?

Is it your car on one chevron and the car ahead on the next?

Is it your car on one chevron, one visible and car ahead on another chevron?

Having done some rough timings, the third option actually works out at pretty much exactly 2 seconds at 70mph.

How interesting....



I've never really questioned the concept because I was happy with the 'obvious' definition - I mean the definition that seemed obvious to me.

I think it means that you shouldn't have covered chevron number two before the car in front reveals chevron number one. So the suggested interval is:

Chevron 1 + interchevron gap + chevron 2.

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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

Yeah, good point you make there. The third option is what I've always assumed and the one that seems to be the correct distance when I drive this particular section.

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Why can't we just use Common Sense?

My only problem with the chevron thing is that the safe distance changes with speed, hence the logic of the two second rule.

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Former Military Police Officer and accident investigator

That's my understanding too - but as we've seen here, it isn't intuitively obvious.

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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

My experience - even on the most crowded of roads. Maximum time lost through this in a 50 mile journey is measured in tens of seconds - two seconds per additional car that takes advantage.

It's less ambiguous in France:

TWO of the white stripes along the side of the road, between you and the driver in front!
They have signs up near junctions [One for DANGER, Two for SAFETY] and a motoring personality (Alain Prost or similar, not Clarkson) on telly every night for 5 minutes hammering home the message about safer driving.
The length of the stripes varies for different types of road, to maintain the two second differential at maximum permitted speed.

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Time to take responsibility for our actions.. and don't be afraid of speaking out!

The most important road safety message I learned while driving was that you should not ever drive so fast that you can't stop in the distance you can see to be clear. If you add to that something about paying attention to what is going on and asuming that people will run/drive out in front of you and allowing for that then that pretty much covers the most important things to think about while driving.


What law is that then?

I agree that people should be able to overtake on either side, it doesn't really matter and is explicitly permitted by the highway code in one-way streets.
However I also believe the "keep left" rule should be enforced a bit too.

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Andrew.

I'd only add one other bit to this - that you had a good idea of what your stopping distance is and can judge that distance.

In normal road driving, you don't need to know what your minimum stopping distance is - you need to know what it isn't. You should not normally be planning to use maximum braking effort so in any driving situation, you should be adjusting your speed so that you know you will be able to stop comfortably within the distance you can see to be clear or at the point where you know you will have to or are likely to have to stop (e.g. approaching a T-junction). It's not practical to regulate your speed (and therefore stopping distance) for the totally unforeseeable (a tree falling across the road) although you can regulate for the improbable but possible (a pedestrian stepping into the road from behind a bus) on the basis of the relative probability of the event actually occurring. That assessment of relative probabilities is, I think, the result of a higher level of hazard perception that drivers only really develop with experience (and good attitude).

I think that's one judgement - not two. I'd write it like: "that you have a fair idea of your stopping distance at all times".

We don't need a highly accurate idea of the stopping distance unless we're driving right on the edge of safety (as a Police driver might on route to an emergency). Instead we need to leave a large margin for safety, comfort and error by planning our speed on the basis of firm braking rather than emergency braking.

I also think that in the real world we're making time judgements not distance judgements.

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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