Speed differentials

[Revian]

I've been (too much) on motorways this week... Though the drive to Sandsend was nice...

Anyway... When I'm overtaking, especially on M ways, I dont like going past slower vehicles too slowly.... Nor do I like being overtaken slowly. It seems safer all round to do it briskly. What's folks thoughts and strategies?

Ian

[Mr Cholmondeley-Warner]

Yup. Minimise TED (time exposed to danger). Mark Kendrick has a nice video entitled Advanced Roadcraft that includes motorway driving and demonstrates this very fact. Expensive but a good watch.

[Playtent]

Yup. Minimise TED (time exposed to danger). Mark Kendrick has a nice video entitled Advanced Roadcraft that includes motorway driving and demonstrates this very fact. Expensive but a good watch.

Just watched the first few seconds of the video and he is talking about the crest but doesn't give the cyclist any further consideration. Should he not position closer to the centre white line to discourage the Fiesta following the cyclist from overtaking and forcing 3 abreast? He also doesn't mention the right hand turn on the crest which has a car coming out yet mentions the houses.
Talking about overtaking and doesn't mention the horse warning.

Apologies for going off topic.

[Mr Cholmondeley-Warner]

That's actually a different DVD, and I don't like it as much, however I still found it somewhat useful. Commentary can always be pulled to pieces, there's always going to be something you miss, something someone else sees that they think is more important ... I'll get you to do some next time we drive together

[Playtent]

That's actually a different DVD, and I don't like it as much, however I still found it somewhat useful. Commentary can always be pulled to pieces, there's always going to be something you miss, something someone else sees that they think is more important ... I'll get you to do some next time we drive together

You'll never do it again if you listen to me! You have to remember the speeds I'm used to doing it at compared to you old boys.

[Horse]

Yup. Minimise TED (time exposed to danger).

Although . . .

. . . There are times when a small speed differential may be wise. For example, when in a clear lane passing slow-moving traffic there's a high chance that one of the drivers will spot an opportunity to get ahead.

On motorways these days it's not uncommon to see vehicles speed up apparently at random. Ending a phone call? Then concentration changes focus to getting a move - while still thinking about the call . . . If they're tagged on the end of a row, moving out might be the next action.

Perhaps there are occasions when the overtaking method shown in the video could be adapted: instead of maintaining speed through the manoeuvre, close up at modest speed then get a move on just as you pass. What's the potential benefit? Where's the speed change decision point? There's a point where, once you decide to go, if the other driver decides to move sideways then acceleration would be the better option than trying to react and brake. But . . . the question then is "What did you miss - why's he decided to move?"

[Mr Cholmondeley-Warner]

Well, yes. Actually Mark's mantra in the film is "avoid being 3 abreast", but it boils down to a very similar thing. If you can be always next to a space, that's safest. If you can move sharply between spaces when traffic to the side is apparently placid and unlikely to cause nasty surprises, that's second best. If there's some doubt about what traffic to the side may do, caution is mandated, which may involve sliding past slowly with eyeballs on stalks, hand poised over the horn, ready to take any different action that may be appropriate as circumstances change.

There are things you can do to maximise your chances. Sometimes you can leave a clear lane between yourself and any suspect vehicle, or if that's not possible you can position yourself within your lane to optimise space. You can choose to delay an overtake until it's safer - when a space reappears next to you. On a motorway my unbreakable driving pattern used to always be to try and maintain a constant speed and just change lane as necessary. Nowadays I'm a bit more flexible, more willing to slow down a little sometimes to maintain the safety bubble. Overall it makes very little difference. Reading the traffic ahead is key to all this - is truck A catching up truck B in lane 1? Is lane 3 free? Yup - so move over now, before truck A pulls out in front of me. Are there brake lights ahead? Ease off ever so slightly - perhaps 2 mph, but crucially the car is ready to slow abruptly if required. What's the vision? Would it be improved from another lane? If it's safe, let's move over then.

[Horse]

Oh - you've reminded me: if it's a foreign-reg left-hooker HGV, wait, check for any hint of wobble from 'straight ahead', then GLF to get through the killing zone ASAFP

[Mr Cholmondeley-Warner]

Indeed - combined with as much lateral space as you can generate.

[R_U_LOCAL]

"Avoiding three abreast" was becoming a bit of an old fashioned aim as far back as 1999 when I first qualified as an instructor. The ever increasing volume of traffic on motorways was making it more and more difficult and advanced students were using up too much of their "spare" mental capacity in trying to time their overtakes perfectly that at times they had little capacity left for the other vital considerations.

So the emphasis on avoiding three abreast (or is it abrest? I always forget!) was allowed to slowly diminish over time to the extent that it's not really taught as a "golden" rule anymore - just one of many considerations when overtaking on the motorway.

It's much more important to learn how to "read" a line of traffic - spotting slower moving vehicles and closing gaps early so that you can identify the vehicles which will change lanes, sometimes before they even know they're going to do it themselves.

As for speed differentials, I'm happy with a high differential on light-to-medium trafficked motorways, but where the nearside lanes are well occupied, my preference is to carry less "plus" speed into overtakes.

When travelling at very high speeds, my preference is, wherever possible, to keep a full lane between my vehicle and the ones I'm passing. Keep your wits about you and look for the classic visual clues from other drivers and you'll soon develop an ability to correctly choose your passing speeds.