Undertaking on the motorway.

[Observer2]

RUSSELLM said:

Observer2 said: An oncoming vehicle suddenly swerving and crashing head on? You can't make allowance for that sort of event. Can't you ?

No, you can't. By definition, we cannot plan for the totally unpredictable. However, there is a point at which a very improbable event becomes foreseeable. If we are concentrating, observing and anticipating sufficiently well, we have a chance of adapting our driving plan for the exceptional, highly improbable event. But no plan will cope with (for example) an car that swerves into our path with no warning.

RUSSELLM said:

So what are the minimum stopping distances for in the highway code ? Was it just to fill a page ? Sorry for my ignorance, I'm confused

To my mind, they serve very little useful purpose (even if they were accurate). In ordinary driving, we don't need to know exactly what our stopping distance is. We need to know what our stopping distance isn't. Thus, if you are approaching a junction, you are not going to start braking at the furthest possible point at which you would have to start braking in orer to just stop in time with maximum effort. You will start braking at some point considerably before then which you know will allow more than enough distance to stop.

[volvos70t5]

I agree with Observer2 (welcome to PH BTW - What's your story? PM if you prefer) The key issue is what can we "reasonably expect" to occur.

On a B country road we can reasonably expect horse riders to be out and about, therefore observance to BATSITDYCSTBCARETRC* is crucial. But where the road is clear and there are no hazards then GLF!

On a motorway we can't reasonably expect a juggernaught to jump the central reservation (I know it happens but very infrequently) but even when it does, good observational skills shoudl help the alert driver to deal with it.

* = Being able to stop in the distance you can see to be clear and reasonably expect to remain clear.

[Flat in Fifth]

Observer2 said:

Flat in Fifth said: If you try to apply 2 seconds gap in the dry nad 4 seconds in the wet then you won't go far wrong. I agree with the principle of increasing separation in the wet but suggest that it is NOT on account of increased stopping distance, because that will apply equally to you and the vehicle in front. However, a wet road is likely to be accompanied by reduced visibility because of rain or spray and increased risk of something unexpected such as car ahead skidding or taking evasive action. Those are the reasons why a longer separation is advisable and why longer separation is also sensible when visibility is reduced by mist or fog.

I agree in principle, when one is discussing a column of vehicles all under braking.

However you have to factor in the issue of vehicles ricocheting off each other and the barriers and thus debris being strewn around the place.

The ideal gap that we should leave is, dare I say, at times quite impractical because too many drivers are unaware of what is really needed.

Equally you are a good 2 seconds behind someone, most people have not a clue and think you are content to sit and follow in their wake.

btw what happened to observer (1?)

FiF

[observer]

Flat in Fifth said:

btw what happened to observer (1?) FiF

He had trouble logging in so created an alter ego. Clever disguise, huh?

(If moderator reads this, you can delete "observer2" because I have managed to resurrect myself.)

[Flat in Fifth]

observer said:

Flat in Fifth said: btw what happened to observer (1?) FiF He had trouble logging in so created an alter ego. Clever disguise, huh? (If moderator reads this, you can delete "observer2" because I have managed to resurrect myself.)

Cheers, conspiracy theory ruled out then.

I had trouble the other day but figured it out eventually. Something changed to login, possibly longer password length allowed that I'd never noticed before. Suspect all this time password had been truncated and Mr Observant (not) here had never noticed.

All the best

FiF