Motorway 'safe' distance chevrons

[johnao]

25NAD90TUL said:

What would you do? Remain in Lane 2, or pull into Lane 1? In this photo the camera car, driven by a Police Advanced Driver will have considered pulling into Lane 1 given the available gap behind the Lorry. What was his decision?

Like anything in AD, it just depends.

If there was no one behind in lane 2 pressing me to move over to lane 1, I'd stay in lane 2. This would mean that I was positioned in lane 2 ready to pass the LGV ahead in lane 1, the LGV driver would see me in his mirror earlier than if I was in lane 1 and, in addition, this position gives me the advantage of early vision around the left hand curve ahead.

If there was a following vehicle in lane 2 or vehicles in either lanes 1 or 2 that are likely to catch up with me well before I reach the LGV then I would pull over in to lane 1 and let them pass.

[Vipers]

johnao said:

Like anything in AD, it just depends.

If there was no one behind in lane 2 pressing me to move over to lane 1, I'd stay in lane 2. This would mean that I was positioned in lane 2 ready to pass the LGV ahead in lane 1, the LGV driver would see me in his mirror earlier than if I was in lane 1 and, in addition, this position gives me the advantage of early vision around the left hand curve ahead.

If there was a following vehicle in lane 2 or vehicles in either lanes 1 or 2 that are likely to catch up with me well before I reach the LGV then I would pull over in to lane 1 and let them pass.

This I think highlights the problem, I don't disagree with your thoughts, which differ from mine, but what if plod decides you should have pulled back into L1, and books you, worrying.

Bty I don't disagree with your thoughts, good stuff.

[Red Devil]

25NAD90TUL said:

Vipers said:

Just found this thread, very interesting.

I wonder though why these chevrons are only one or two roads, unless I have missed them.

My driving south once a year consists of Aberdeen to London via M74, M6, M1, and I can only recall seeing them on one stretch of the road.

They're very frequent on the M5, especially in areas near damp ground where sudden patches of thick fog may be a possibility or in other similar accident blackspot areas.

I know that the thread title is about motorways but chevrons are by no means exclusively to be found thereon.
They appear on dual carriageways as well . Here's one I use regularly - https://maps.google.co.uk/?ll=51.53096,0.4319&...

[Vipers]

Red Devil said:

I know that the thread title is about motorways but chevrons are by no means exclusively to be found thereon.
They appear on dual carriageways as well . Here's one I use regularly - https://maps.google.co.uk/?ll=51.53096,0.4319&...

Interesting, but still random, I wonder what initiates the "Oh lets put some chevrons on the road here" debate in local council.

I am assuming that road is NSL.

[Red Devil]

Vipers said:

Red Devil said:

I know that the thread title is about motorways but chevrons are by no means exclusively to be found thereon.
They appear on dual carriageways as well . Here's one I use regularly - https://maps.google.co.uk/?ll=51.53096,0.4319&...

Interesting, but still random, I wonder what initiates the "Oh lets put some chevrons on the road here" debate in local council.

I am assuming that road is NSL.

Here's another d/c. This one is the responsibility of the Highways Agency, not the local council.
Whichever it may be, I have no idea what the criteria are on which any decision to put them in is based.

[SK425]

Red Devil said:

I have no idea what the criteria are on which any decision to put them in is based.

I'm sure I've seen it suggested (maybe even somewhere in this thread?) that they are used on long straight stretches because without bends and their cross-views you can more easily miss important stuff like a wave of brake lights or a patch of slow/stationary traffic further ahead - because at the sort of autopilot following distances a lot of people use, on a long straight you can't see so much past the vehicle immediately in front. No idea if there's anything in that or if it's just pub chat, but it doesn't seem completely implausible.

The two links you posted were on straights, and the chevrons I know on the M11 are on a straight bit. Are they any sections of chevrons on bendy bits?

[25NAD90TUL]

SK425 said:

I'm sure I've seen it suggested (maybe even somewhere in this thread?) that they are used on long straight stretches because without bends and their cross-views you can more easily miss important stuff like a wave of brake lights or a patch of slow/stationary traffic further ahead - because at the sort of autopilot following distances a lot of people use, on a long straight you can't see so much past the vehicle immediately in front. No idea if there's anything in that or if it's just pub chat, but it doesn't seem completely implausible.

The two links you posted were on straights, and the chevrons I know on the M11 are on a straight bit. Are they any sections of chevrons on bendy bits?

That is a good point SK and one that hadn't occurred to me but yes a lot are on straights where cross-views are not available. Good point and I'm sure that is right in some circumstances.

[Vipers]

Interesting

http://www.trafficsignsandmeanings.co.uk/painted-c...

[LordGrover]

25NAD90TUL said:

SK425 said:

I'm sure I've seen it suggested (maybe even somewhere in this thread?) that they are used on long straight stretches because without bends and their cross-views you can more easily miss important stuff like a wave of brake lights or a patch of slow/stationary traffic further ahead - because at the sort of autopilot following distances a lot of people use, on a long straight you can't see so much past the vehicle immediately in front. No idea if there's anything in that or if it's just pub chat, but it doesn't seem completely implausible.

The two links you posted were on straights, and the chevrons I know on the M11 are on a straight bit. Are they any sections of chevrons on bendy bits?

That is a good point SK and one that hadn't occurred to me but yes a lot are on straights where cross-views are not available. Good point and I'm sure that is right in some circumstances.

I was on M4 East yesterday and they were on a curved section between Swindon and Chieveley IIRC.

[Test driver]

25NAD90TUL said:

I much prefer to leave a 5 second gap at 50, 7 second gap at 70 etc, imo the chevrons are not far enough apart as others have said, what are they 2 second intervals? Not enough at anything above 30mph imo.

I guess they are there for drivers who have no comprehension of a safe distance, I ignore the chevrons and maintain my own safe distance, I watch the vehicle in front pass a marker, say a bridge, and then count in seconds until I pass the same marker. I did that with an examiner onboard, and specified in commentary that I was 'maintaining a 7 second gap at 70mph', all he said was 'excellent!'

How many times have we all seen drivers less than the two chevrons apart? Me, many.

I often see idiots like you being undertaken by hundreds of cars as you refuse to pull over and instead cause massive tailbacks.

[7mike]

Test driver said:

I often see idiots like you being undertaken by hundreds of cars as you refuse to pull over and instead cause massive tailbacks.

I've been driving since the eighties; cars/coaches/lorries/adi/fleet trainer. In all that time if I could add up the number 'undertakes' I've seen I bet it doesn't run into the 100s. I salute you sir on your observation skills

[Toltec]

Test driver said:

25NAD90TUL said:

I much prefer to leave a 5 second gap at 50, 7 second gap at 70 etc, imo the chevrons are not far enough apart as others have said, what are they 2 second intervals? Not enough at anything above 30mph imo.

I guess they are there for drivers who have no comprehension of a safe distance, I ignore the chevrons and maintain my own safe distance, I watch the vehicle in front pass a marker, say a bridge, and then count in seconds until I pass the same marker. I did that with an examiner onboard, and specified in commentary that I was 'maintaining a 7 second gap at 70mph', all he said was 'excellent!'

How many times have we all seen drivers less than the two chevrons apart? Me, many.

I often see idiots like you being undertaken by hundreds of cars as you refuse to pull over and instead cause massive tailbacks.

You are assuming he is not already in the left lane. You are assuming that if he is not in the left lane that there is nothing to his left.

If I were to make an assumption based on your post I might say...

I see thousands of drivers just like you who never look further than the bumper of the car in front. You end up having to brake on a motorway causing miles of tailbacks.

Go and read the thread and you will see how we discuss how and where extended following distances are appropriate.

[UK952]

After wading through 13 pages, I would just like to point out the chevrons are only positioned for one speed and presumably good conditions, they don't take into account hgv's or those towing, rain, sleet etc. I guess in snow they are hidden. Anyway always struck me as dumbing down and some 2 second rule or keep left signs would be a better investment.
Tony

[SK425]

UK952 said:

After wading through 13 pages...

Would have been 78 if we'd all done that

[UK952]

SK425 said:

UK952 said:

After wading through 13 pages...

Would have been 78 if we'd all done that

Apologies, new tablet, sorted (the multiple posts) now

[Vipers]

UK952 said:

Apologies, new tablet, sorted (the multiple posts) now

Now you will confuse some of our readers.......... Wots all this 78 pages crap.

[UK952]

Vipers said:

Now you will confuse some of our readers.......... Wots all this 78 pages crap.

Hence my (the mutliple posts) comment in my apology! I did think about just deleting them to make SK425 look a bit random.

I do also realise that some may think it is my medication that caused the problem rather than my technology

[Vipers]

UK952 said:

Vipers said:

Now you will confuse some of our readers.......... Wots all this 78 pages crap.

Hence my (the mutliple posts) comment in my apology! I did think about just deleting them to make SK425 look a bit random.

I do also realise that some may think it is my medication that caused the problem rather than my technology

What I was meaning was those who read this page for example today, having no idea of your multiple posts may wonder to the reference. Good luck with the tablet, I found it getting use to at first especially auto correct.

Good post by the way, chevrons are not the end all and don't serve all situations, although one has wonder if drivers need chevrons to show them how far away they should be from the vehicle in the front, maybe they shouldn't be on the roads at all.

[Observer2]

Toltec said:

You mentioned this earlier and it made me consider it. If the gap is to react then why would it need to be greater in the rain? I think the simple answer is that two seconds would still work, but you need to be going slower.

I haven't read forward to the end of the thread to see if this has been answered. The really relevant reason, IMO, is that in wet conditions there is greater probability of difference in braking performance. In dry conditions it is reasonable to assume you will stop as quickly as the car in front. In the wet, he may stop more quickly, so a larger gap mitigates the risk of the possible differential.

[WinstonWolf]

25NAD90TUL said:

WinstonWolf said:

I'll reply there to save thread drift, suffice to say it was never a danger to anyone, merely an annoyance to me

I suppose the maths stands up in your favour on that one too then! I suppose you worked out the probability of you breaking down and decided like that did you? What did you use a Chi square?

You're growing on me but I have to say you do seem to use some categorical statements. This one again is a case in point.

Now I really am out, have to pick my wife up, thing is here in Cornwall, everyone uses a large gap on the 'motorway' actually it's a hundred mile A road, but we're not that much of country yokuls, it does have two lanes and a central reservation. Large gaps are de riguer here, apart, of course from when holiday makers from the hustle and bustle arrive, then our roads descend into chaos, sounds like a joke but sometimes, very sadly, it ends badly, that's why so many graves road-side.

Best wishes anyway Rob, you're growing on me, albeit very little, when I get back I'll have a look at that prognosis in the other thread.

Does anyone want to friend me? My current status is 'billy no mates' PMSL...Best wishes all!

Sorry to drag this back up, but my OH was driving along in a 4000 mile, 14 plate hire car at the weekend and the gearbox seized totally on her completely locking the wheels

She left a continuous pair of 11's down the road, the following vehicle managed to stop without hitting her.

The car did not come to a complete stop, it skidded to a rest exactly as I predicted.