Driving at Night

[Another Bill]

An interesting argument I once heard from a work colleague was, to avoid using main beam when there was any likelihood possibility of oncoming traffic, even when road ahead was completely clear.

His argument was two fold…

1. If you allowed yourself to drive faster as a consequence of the improved view from main beam then the moment you had to dip, by definition, you’d be driving too fast. You might slow as well but that tends to come after dipping so, for a moment or two, you’d be too fast for safety.

2. If you use only dipped beam, your pupils (or is it irises?) will expand more and settle at that level, allowing generally more sensitive vision. As soon as you enable main beam the pupils shrink, a switch to dipped will be all the more hazardous until, after a few seconds, the pupils react.

Couldn’t make up my mind whether to agree with him.

[Strangely Brown]

And you probably have noticed that the muntjac population in Berkshire / Oxfordshire has surged alarmingly.

Don't know about the population here but this sign is regularly updated.

Ashdown Forest

It read 200 when I passed it today and was over 200 only a few weeks ago.

[Horse]

1. If you allowed yourself to drive faster as a consequence of the improved view from main beam then the moment you had to dip, by definition, you’d be driving too fast.

2. If you use only dipped beam, your pupils (or is it irises?) will expand more and settle at that level, allowing generally more sensitive vision. ... until, after a few seconds, the pupils react.

Couldn’t make up my mind whether to agree with him.

1 makes sense

2 though, perhaps not. Full night vision wide open pupils takes IIRC up to 20 minutes - but the first oncoming vehicle will clobber it.

However, a mate had the similar theory to drive on sidelights to look beyond the lit area.

[Gareth]

1. If you allowed yourself to drive faster as a consequence of the improved view from main beam then the moment you had to dip, by definition, you’d be driving too fast.

I think this line of argument pre-supposes that the driver doesn't slow down for potential hazards and is using main beam always rather than, say, periodically dipping to look for oncoming lights.

[Another Bill]

However, a mate had the similar theory to drive on sidelights to look beyond the lit area.

I’d not go that far. But If feeling more mischievous than usual, I could argue that tail lights are not necessarily a good thing.

If the vehicle in front has tail lights we might feel confident that we know how big a gap is in front, and allow that to influence our own speed.. Trouble is, the thing in front may not have tail lights. It might be a crashed or broken down vehicle with flat battery, or a drunken pedestrian, or a fallen tree, etc etc etc.. We’re supposed to be able to stop in time for any of these so, arguably, the presence of tail lights actually gives a false sense of safety which might encourage excessive speed?