Safe Speed Forums

It's that time of year again when I find driving at night on unlit roads quite challenging.

I wear spectacles and know from conditions of bright sunlight that bright lights tend to affect spectacle-wearers more than people who don't wear them.

The same applies at night when faced with bright headlights for whatever reason, whether badly adjusted or a vehicle loaded in the rear without the headlights being adjusted downwards, fog lights on for no good reason, high-powered xenon lights, 4-wheel drives, vans and HGVs with lights higher up than cars, failure to dip or a combination of these.

Although I have fitted bulbs of 50% higher power than standard on my (1999) car, the dip is adjusted correctly so that I don't dazzle other drivers. My rule of thumb is that if light enters the vehicle in front through its rear window when following at a safe distance on dipped headlights, your lights aren't adjusted properly.

All this means that generally I can't drive safely at more than 45 mph on dipped lights on an unlit rural road, especially if there isn't a white line at the edge and the road markings are obscured by muck or worn away. Frequently I will be dazzled by an approaching vehicle for any of the reasons quoted above. Lighting defects seem to be routinely ignored except at MOT time.

My eyes are tested regularly and I wear correct prescription lenses which are glass not plastic so that they don't get scratched when out on the bike. So I don't have an eyesight problem other than having to wear spectacles.

Am I alone? I really can't see how other drivers can travel safely at 60-70 mph on dipped headlights in such conditions (sometimes with only the left-hand headlight working). I know that we do it, me included, on a dual carriageway on the assumption that if the vehicle in front hasn't hit anything lying in the road or parked on it then we won't either.

What does everyone else think?

I too wear specs, but don't have any problems at night, in fact I do more night driving than day.

To pick up a few points you've made...

Being dazzled by oncoming traffic... Are you sure that you're looking in the "right" place? (IIRC you're an IAM member, so I may be on a course of "egg-sucking education" here..). I note that you have extra-bright bulbs fitted, could oncoming drivers be seeing these as "undipped" and consequently being slow to dip in response?

Doing 70 on dipped headlights... No choice if you're following someone, the "ST" bit of COAST should mean you've plenty of time to react if the car in front does something untoward. If you're #1 in the queue they should only be dipped for the briefest period suitable for safety and courtesy to oncoming traffic - one thing I find very annoying is people who dip for oncoming cars then, once they've gone, carry on on dipped lights for ages (always assuming that they've ever gone onto main beam in the first place!).

Have you tried contact lenses? I wear them some of the time, but frankly, don't find much if any difference.

It could simply be that it comes down to individual variations in our eyes. Some react more quickly to changes in light levels, some are more sensitive to bright lights than others, etc.

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"Politicians are the same the world over... We build bridges where there aren't any rivers." - Nikita Kruschev

I've noticed that a lot of cars seem to have brighter lights than they did. Some are so bright that one has fight the urge to swerve into the verge to avoid them! Would I improve the situation overall if I fit super-strength lights myself this weekend, or would that selfishly make matters even worse?

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I must say I have no problem - and I also wear specs full time.
The only time I have problems is after they've gritted the roads and my headlights get all mucked up. But then I pull over and wipe them off.

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Only when ideology, prejudice and dogma are set aside does the truth emerge - Kepler

Same here.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

et moi aussi

In response to BOTH of the above comments about 'extra-bright' lamps, for example the 'philips extra vision' or whatever is completely legal & carried an 'e' comformity. It's the SELFISH idiots that manually adjust their dips, either via thumbwheel or by screwdriver to point far too high thinking this will make them see better.

pogo: Yes, the possiblity exists but only if badly adjusted & dip is too high.

'werk: Fit 'em if you want, just make sure you dip them slightly more than nomal.

I recently changed to HID xenons, they make the world a brighter place and now I CAN see where I'm going. They are adjusted correctly (actually tweaked to be a little low) to prevent dazzling and I have NEVER have anyone flash me thinking I've got hi-beams on, or pulled by BiBs. This makes it entirely possible to drive at 70mph on dark roads without full beam as the level of illumination is ideal with a sharp cut-off at the end of the beam with very little scatter.

So what I'm saying is - it's NOT the brightness, it's the p1$$ poor adjustment!

Agreed absolutely!

I drove a friend's car the other day, it's fitted with these demon Xenon-arc lights. They are incredibly bright but the beam-control on dip is absolutely superb. I'm sure that you're right that the problem is more caused by people putting very bright (albeit legal) bulbs into less-than-perfect headlight systems - they don't control the dip cut-off very well regardless of the output of the bulb, it's just a lot more offensive when there's even more light to "spill".

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"Politicians are the same the world over... We build bridges where there aren't any rivers." - Nikita Kruschev

I have to say I, as a fellow middle-aged spectacle wearer, suffer from exactly the same thing. On a quiet road where I can use main beams, no problem, but if there's a steady stream of cars coming the other way I really can't see much at all in front of me and like you feel I need to slow down to a maximum of 45-50 mph.

A few years ago a was doing a commute which involved about 15 miles of unlit SC A-road which I found quite stressful for this very reason. It is somewhat embarrassing to be driving at 20 mph or more less than the speed I know would be safe in the light.

I wouldn't like to say whether it is the 15-20% of badly adjusted headlamps that cause the problem, or the total amount of light even from well adjusted headlamps.


On a dual carriageway the oncoming traffic is much further to your right, so the dazzle problem is greatly diminished. Also, even at night, there's generally traffic ahead which also illuminates the road in front.

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"Show me someone who says that they have never exceeded a speed limit, and I'll show you a liar, or a menace." (Austin Williams - Director, Transport Research Group)

Any views expressed in this post are personal opinions and may not represent the views of Safe Speed

I don't wear glasses but I too struggle sometimes on busy, twisty, unlit roads but mainly only at night. I remember particularly arduous trips on the A65 between the M6 and Long Preston, in a variety of vehicles.

I'm not sure why I struggle, perhaps a lack of confidence? I don't seem to have as many problems on roads I know well.

I posted this time last year about not being able to see the road markings very well when it's dark. I say they need to be repaired with some nice new paint, others on here said I needed my eyes testing. Had eyes tested two weeks ago. Very good eye sight, but my left eye is slightly weaker and was precribed glasses to read with whe I'm tired. Only needed to use them twice...

Then saw an article in AutoExpress (I think) that said 70% of road marking were in a dangerous condition, which kind of summed up what I had thought.

Keep your windows and light spotlessly clean helps.

It costs a little more (actually a lot more) but next time you change glasses, go for Zeiss lenses and get them with the best AR coating that the optician recommends.

I do this solely on my driving glasses, which are monofocal (correction for infinity only), and these glasses are kept lovingly in a leatherette case with cloth around them in the car, and are worn solely when driving. It's a great improvement and until I did this I had similar scatter problem from others' lights.

I see two difficulties described in Cyclist senior's post - glasses, and poorly adjusted headlights.
Second problem first....
If you approach a righthand bend from below, and a car rounds the corner coming towards you, the dip of his lights will direct the light AT you, giving the appearance the lights are not dipped.
Otherwise there is little YOU can do about the oncoming vehicles lights.
I agree that badly adjusted lights, and BLOWN BULBS are more prevelant at this time of year - I suspect because the drivers dont have daylight hours and warm garages in which to rectify the problem.
Your description of guaging the adjustment of your lights seems fine - I stop facing a blank wall from about 20 feet away, and set the level, then check it in a similar manner to yourself.

Glasses are a different kettle of fish. Different prescriptions have different effects. The curvature of the lens surfaces varies, and some combinations are worse than others.
I have glasses, where one lens is PLAIN with no prescription, while the other is a curious prescription, which with a good eye, distorts the view across one diagonal axis and not the other - with my good eye, the TV looks like a parralellagram!
This is achieved with front and back surfaces curved in two different directions. A point light source will produce a reflection from the front surface, AND the inside of the rear surface. Some of that second reflection then bounces back to the eye from the INSIDE of the front surface - and is slightly displaced due to the prescribed curvatures. The brighter the light, the more a secondary image appears next to the pinpoint of light you can see.

I hope you can see why some prescriptions show this more than others.
The choice of glass lenses is good, and I would ask for multicoated lenses next time too - they ARE worth the extra money.
Basically a thin rare metal coating is applied which interferes with the surface reflections on the front and back surfaces, and cancels them out. You see a sharper crisper image as a result - top quality camera lenses have been made this way for years with good reason.

SNAP! I see Roger has posted the same advice as I typed mine!!

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Time to take responsibility for our actions.. and don't be afraid of speaking out!

I wear glasses and I have no problem with night vision, in fact I suspect my night vision is better than average.

Leading me to suspect these two aspects of vision are unrelated.

Maybe it's because you were a good boy and ate all your carrots when you were little!!

Seriously though, does anyone have experience of your vision changing at different times of day or year?
In theory at least, bouts of high or low blood pressure could affect your vision, and vitamin D (in the carrots) is supposed to improve it.

I hate having the heater vents blowing in my face because it makes my eyes dry and eventually - sore, yet need the refreshing breeze. My preference is therefore for glasses which have large lenses, or like my sunglasses - wrap around to exclude the draft.

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Time to take responsibility for our actions.. and don't be afraid of speaking out!

I don't think it's anything to do with glasses - it's just that some people are more sensitive to bright lights than others.

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"Show me someone who says that they have never exceeded a speed limit, and I'll show you a liar, or a menace." (Austin Williams - Director, Transport Research Group)

Any views expressed in this post are personal opinions and may not represent the views of Safe Speed

Not strictly in the lines of the question asked, but if the degree of sight correction required changes from day to day, this is a strong indication of uncorrected or poorly correected blood sugar in either a diagnosed or undiagnosed diabetic.

Thanks for the advice about lenses and coatings, that's very helpful.

Last night I had to drive in the dark from here to Barrwoford, Lancashire, and back and had plenty of opportunity to observe the problems. Even though it was well above freezing 4-5 degrees C the roads were wet with salt and it was spraying everywhere. When I got onto the A658 from Knaresborough to Pool Bank nearly all road markings were obliterated by the muck plus with the headlamps being coated with muck most people were driving at 40-50 mph in NSL areas. I was following a car towing a trailer who kept speeding up and slowing down in an erratic manner. When I overtook on a 3-lane section I could see his nearside headlamp was out on dipped. Over the tops to Colne it was dense fog and at 25 mph I couldn't see the white lines on the edge or in the centre. It was not helped by the van behind with his lefthand headlamp pointing up in the air and dazzling me via the dipped mirror, so I pulled over to make him pass.

I saw all the lighting defects you can imagine - no left headlamp, no right headlamp, dazzling dip beams, either one or both. Obviously these only ever get picked up at the annual MOT test - or do they?

I came back via the M65 and M6 to Tebay, and over Stainmore. In places on the M6 north of Lancaster the fog was so dense that 30 mph was the fastest I could go and still see the white lines. Beyond Ravenstonedale, over Ash Fell and coming up Stainmore from Brough it was even thicker and 20-25 mph was my limit, although articulated HGVs were coming past at 50 mph, although I could see from their headlights' penetration of the fog that they couldn't see any more than I could.

I find a useful rule-of-thumb for judging whether or not I'm driving too fast for lighting conditions (or generally for that matter) is to note an object (such as a road sign) when it comes into view in my headlights, and then to count the number of seconds it takes for me to pass that object. I take the number of seconds and subtract one (for reaction time) and then multiply it by 40. This gives me the speed from which I should be able to make an emergency stop on a good, dry road surface. Or multiplying by 20 gives me the speed from which I should be able to stop by braking moderately, or make an emergency stop on a wet road. If my actual speed is in excess of this figure then I'm going too fast.

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Only when ideology, prejudice and dogma are set aside does the truth emerge - Kepler

Has anyone looked into the "splash" issue with certain types of lights.

I too use the trick of fiddling with the thumbwheel until the light is below the rear window of the car in front. In this case my GFs car which is a Nissan 200SX so comparatively low.

This did not stop me from getting an earful for blinding her by switching my (dipped) lights on whilst she was parked facing me, blocking me in, and about to move out of the way.

Apparently my headlights spill a lot of light in other directions anyway. The car has gotten through several MOTs though, so I don't know what is going on.