Safe Speed Forums

A bit of the wall perhaps but...

Am finding that around where I live there are lots of unlit country lanes, the only way to view a reasonable distance is with main beam. A lot of the old signs were clear and readable in main beam with minimal glare i.e. you could see the road clearly and the signs.

Recently a lot of signs have been replaced with new ones with a hi reflective finish. Now if I approach these signs with main beam on I am dazzled by my own light being reflected back at me, so I drop to dipped beam and reduce the area of road I can see.

Anyone else finding this a problem ??

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Gordon Brown saying I got the country into it's current economic mess so I'll get us out of it is the same as Bomber Harris nipping over to Dresden and offering to repair a few windows.

Chaos, panic and disorder - my work here is done.

http://www.wildcrafts.co.uk

I have noticed this, but it coincided with my car swap in my case. I put it down to the fantastic headlights rather than the signs!

I haven't changed car in this time, so am comparing the effect of the same headlights on differing signs. Though I do find it very distracting and a step backwards.

Sometimes signs can be too visible.

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Gordon Brown saying I got the country into it's current economic mess so I'll get us out of it is the same as Bomber Harris nipping over to Dresden and offering to repair a few windows.

Chaos, panic and disorder - my work here is done.

http://www.wildcrafts.co.uk

I've noticed it here and there. There's a particular pair of newish low bridge warning signs near here that are absolutely blinding.

It's not some bloody euro-spec thing is it? They seem to have raised 'overspecification' to an artform. (In both senses of 'overspecification' too many parameters, and inappropriately extreme values for sensible parameters.)

I can just see some Brussels b-euro-crat saying : 'What's the highest reflectivity that money will buy? We'd better have that now because the spec needs to last 20 years and if we don't have that as a minimum we'll be even further behind in 20 years time."

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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

Have no idea, road signage isn't my strong point, Safety Signs & Signals Regs only cover safety signage - Colour, Shape & Classifications. Doesn't specificy reflectivity.

Will have a nose around...

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Gordon Brown saying I got the country into it's current economic mess so I'll get us out of it is the same as Bomber Harris nipping over to Dresden and offering to repair a few windows.

Chaos, panic and disorder - my work here is done.

http://www.wildcrafts.co.uk

I have noticed not only more reflective signs but they are getting more reflective.

Improved technology? Better reflective materials?

Anyone remember the old studded NSL signs? I still see theme here and there.

I am assuming that, for some reason, they're using the "diamond grade" stuff or similar. Basically it is a polymeric film that acts like a bicycle reflector - over the (fairly wide) capture angle, it reflects light back to the incident path irresepctive of the direction of strike.

I agree that signs seem much brighter than in the past. Especially with HID headlamps in the "main beam on country lanes" scenario in the first post. The pool of darkness beyond the bright signs renders pedestrians/cyclists almost invisible.

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Malcolm W.
The views expressed in this post are personal opinions and do not represent the views of Safespeed.

It's quite blindingly obvious that this is a problem.

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

I emailed Richard Bentley (signing expert) and drew his attention to this thread. This is his reply:

-------- Original Message --------
Subject: Re: Reflectivity of road signs?
Date: Sun, 8 Jan 2006 12:50:18 +0000
From: Richard Bentley <withheld>
To: Paul Smith <psmith@safespeed.org.uk>

Paul

I am aware that there is a drive across Europe to standardise the
retroreflective or microprismatic materials in use.

There are standard materials all of which must meet (or exceed)
certain design parameters, 3M producing one of the most common if not the most
expensive.

Signs should (or must) carry an EU or BSI mark to ensure that they
are compliant, some manufacturers are making signs at the margins of profit, some
authorities manufacture their own signs. So cheaper materials may not be the
best option, some may be too reflective (hence the need for standardisation).

it would be interesting to see if the 'abnormal' signs have a date
mark on the back.

For information, a manufacturer marks the rear of the plate with a
date code system so you can just about work out it was not erected before.

When signs are 'illegal' be that in format or system, those making
them may not want their work to be recognised and the plates go without a mark.

Suggest that at some time the high visibility signs are examined for
BS or EU numbering and the 3"x2" punched or ticked manufacturers label on the rear.

Methinks the cupboard will be bare.

If the sign is defective or illegal and causes an accident, then, the
highway authority would be liable.

Richard

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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

I assume you mean 'retro-reflective', for which I would agree.


I think the problem is related to the distance from the headlamps to the eyes (there are of course other factors), the closer they are, the more light you will see. I once held up a weak keychain LED torch, holding it close to an eye, to one of these signs - the result was astounding. The whole sign was surprisingly bright (yet no-one else will have noticed this).

As a solution, I might suggest that headlamps could be lowered (to within 18 inches of the ground - currently illegal) and have a small illuminator at head-height specifically for controlled illumination of these signs?
Thoughts? (I realise it could be a bit off-the-wall)

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Views expressed are personal opinions and are not necessarily shared by the Safe Speed campaign

Living in an urban area, I don't do a lot of night driving on unlit roads. But there's one location I pass through maybe twice a month, where there certainly is a sign that is blindingly reflective.

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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 find it to be a frequent problem, but I have been noticing what I think are excessively bright signs, i.e. too reflective, for several years now. It may be getting worse, but I don't think it is an entirely new problem.

Best wishes all,
Dave.

Diamond Grade is a 3M trade name. See http://safety.fhwa.dot.gov/roadway_dept ... eet_id.htm I think we are at one.


Onec you get far enough away from the sign that some of your headlight beam misses it (ie morre than about 10 ft), the effective light falling (and reflecting) will be inverse square to the distance.



With headlight beam divergence I doubt this would offer much of a "fix". The fix has to be at source her, ie, put an ND filter over the sign, not affecting its contrast but reducing its brightness/reflectivity.

That is true, but angular displacement (at the sign) would also be reduced as you go further away from the sign, hence the coefficient of reflection of the light back to your eyes would be increased; I don’t know if that’s enough to compensate for the inverse square trend.

I forgot to mention I was around 100ft away from the sign when I did my LED experiment.


The problem with changing the reflectivity of signs is that the characteristics won’t be suitable for everyone (due to many varying factors). Perhaps the solution is to be able to adjust the headlight divergence to suit? I know some cars already have systems for altering the dip angle.

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Views expressed are personal opinions and are not necessarily shared by the Safe Speed campaign

I see where you're coming from - get the physical angular separation between your eyes and the headlights up a bit to ensure that the headlight rather than your eyes get the majority of the bounce-back from the DiamondGrade.


Of course, the further away you are from the DiamondGrade, the closer (in angular terms) you are to the headlight.


Yup - but continuing on the brainstorm angle, wouldn't it be even better if the roadsigns were polarised at a fixed angle and individuals had the option of polarising their headlights at an angle o their choice, attenuating the signs by a percentage to suit them, without doing so to the rest of the background. Indeed, the angle of polarisation could be linked to the dashboard lighting control - dimming both at the same time!

I see what you mean. I think it could work, assuming the polarising filter didn’t attenuate the light output too much. As a refinement, I think that only the light that radiates upwards need be polarised such that the light needed to see objects in the road straight ahead won’t suffer attenuation when passing though such a filter.

Roger, your idea has given me inspiration:
http://www.safespeed.org.uk/forum/viewt ... 1240#61240

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Views expressed are personal opinions and are not necessarily shared by the Safe Speed campaign

I thought that this was simply due to Xenons? If I have the standard 55W bulbs in my car there is no problem with this, but Xenons/100W Halogen bulbs can be temporarily very bright...

However, in the areas where pedestrians are prevelant (say perpendicular kerbs and get bonus marks in IAM/ROSPA) chances are there is enough ambient lighting that this is not a problem:- although this is arguably even worse as you cannot see the unexpected...

I believe the main problem to be a 'brighter is better' philosophy from the materials manufacturers / and by extension the person who specifies the latest / most reflective materials.

Typically, retro-reflective vinyls are supplied in two classes. Class 1 (motorway signs & emergency vehicle markings), and Class 2, standard street / road signs & commercial applications ranges from the poorly reflective to verging on Class 1 - such is the variability of materials!

There are several different manufacturers of Class 1, 3M 'Scotchlite', being amonst them. Sales of this are normally only to authorised road-sign manufacturers except in upto 150mm wide rolls which 'anybody' can buy.

Retro-reflective materials are classified as a light source, so placement should comply to vehicle lighting regulations - no white on rear, no red on front.

New motorway signs are obviously 'brighter' as they utilise the latest materials and are as yet largely unaffected by U.V. degredation / general weathering.

Over-specifying full Class 1 'diamond grade' is not a common occurance, as the cost is prohibative, (Apx. £200 per square metre - trade) but when a quality Class 2 is ordered, it can be 2 or 3 time 'brighter' than a budget grade.

The colour of light being reflected also seems to have an effect. Blueish white (LED torches & xenon HID's) seems to reflect better than yellowish white (Halogen headlamps).

(<tongueincheek>)Could it be that they're installing brighter signs so they don't have to clean them? There are many signs my way that don't ever appear to have been cleaned.