Driving within limits of visibility

Thoie

There's a thread on AH discussing legislating that pedestrians should all wear hi-viz vests. While I like hi-viz vests, I'm not sure this is something you can legislate for. Anyway.

When I was learning to drive, I learned that you always drove within your limits of visibility. For example, if you can only see 30 metres ahead of you, then you drive at a speed enabling you to stop in less than 30 metres.

Do they teach this any more, or is it just that people forget/ignore it?

TwoShedsJackson

They teach it but it's broadly ignored by many drivers. Far too many won't adjust speed for the conditions - if it's 100kmh limit they're doing 100-120 regardless of day or night, rain, ice, fog, traffic, whatever.

microgirl

Oh they still teach it alright - or at least they did when I was learning seven years ago, and when my friend was learning three years ago. But people don't care. Fast is good, mmmkay?

Thoie

microgirl wrote: »

Fast is good, mmmkay?

Hush you, and give me your credit card.

Was actually just looking for you on IM to ask you about when you were learning

BrianD3

This opens a can of worms about night time driving. If you are driving on a motorway at night you can see taillights of car in front for miles ahead (given a straight enough road) However if there is say, a big pothole ahead, at 100-120 km/h on dipped headlights, you'll be on top of it by the time you see it and react to it. Even after you "see" it it will take your brain some more time to process what it has seen and decide the course of action. If it was a different hazard in the road then brain might react faster.

So, should everyone drive on motorways at such a speed that they're able to stop in time no matter what could be sitting on the road ahead. I think you'll find that in that case you'd be unable to go above about 70 km/h on a motorway at night.

Main beam headlights can only rarely be used on M-ways as there will usually be other vehicles around - including oncoming traffic on the other carriageway. If you do get a chance to use main beams then IMO it is accpetable to "remember" what you've seen in the road ahead after you have to turn them off. It's also acceptable to use the lights of other vehicles to illuminate the road. However doing this does not comply with the principle to be able to "stop in the distance you can see to be clear at all times"

Fog is different - because even well lit cars, pedestrians and cyclists become invisible a short distance ahead.

Thoie

Specifically talking about night driving, I think motorways are a bit different (and am willing to be contradicted here) - your limit of vision on a motorway is always going to be slightly greater as all the motorways I can think of have additional lighting besides just your headlights. I don't think I've ever come across a pothole on a motorway, except for where there are current roadworks (eg - current M50 works, and they're a 60kmph zone anyway). It is also a pretty safe assumption that there won't be unlit pedestrians/bikes on the motorway. It can happen, people are stupid, but in x years of driving I've rarely seen a random pedestrian on the road.

The other thing is that you'd rarely have to come to a deadstop for a pothole/object in the middle of a motorway. If you're driving at night there'll generally be some room for manoeuvre, if there's a lot of traffic around with no manoeuvring room, you'll probably be driving slower anyway, as someone up ahead will have slowed down.

For those who did learn to drive within the limits of your visibility, how many of you ignore it (say in fog, or dense rain) and drive at the same speed as always?

ardmacha

your limit of vision on a motorway is always going to be slightly greater as all the motorways I can think of have additional lighting besides just your headlights.

At junctions perhaps but not everywhere.

On a motorway if there is a car some distance in front of you then only a hazard that appears after that car passed by is a real problem, otherwise you might see the car braking or swerving. As motorways have restricted access to pedestrians, animals etc these events are less usual, but of course something could fall from a trailer of a vehicle in front of you.

But this concept has relevance for driving on twisting roads, the proper speed to go around a bend is not that which allows your car stay on the road but that which allows you stop in the distance you can see. In my opinion they should set up speed traps on this basis, with some sort of rangefinder to identify the distance and the ROTR braking distances then any speed over this should be illegal at any point in the road network, without the need for specific signposting.