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Cats eyes road markers? Answered

Over the years I have come up with a variety of ideas - some Impractical, some worked and many that never went beyond the thought or drawing stage.

A long time ago I thought this was a good idea, with no budget or inclination to action it practically I put it up here for comment/critique

In the UK and many other countries the centre and edge of the road is marked with reflective dots. In the UK we call these cats eyes as the inventor was supposedly inspired by the way a cats eyes shine in the dark.

However good though they are they only reflect as far as your light beam reaches. On dipped beam this may not be that for ahead and with the sort of traffic we get in the UK you hardly every get to use the main beam.

My suggestion is to cut a slot down the middle of the road and lay in it a fibre optic cable linking every cats eye in groups of say 50 or 100.

The ides is as the diagram shows the Fibre optic carries your dipped head light far further then it would normally shine without the risk of dazzling other road users.

I think that this would significantly improve road safety at little cost if done when road refurbishment was carried out anyway as at this time the cats eyes are often removed and replaced. The cats eyes could be simpler, lower profile and possibly cheaper to makeas they would only need to be a plastic holder for the fibre.



Best Answer 5 years ago

Interesting idea, but can't work.

Cats eyes work, because the prisms inside reflect all (well, almost all) light back into the direction it comes from. So, all that little light that reaches the tiny cats eye is coming back towards your car and your eye.

With your idea, you will have a lot of losses:
- coupling the light into the fibre
- losses inside the fibre
- splitting up the received light between X transmitting eyes
- and the worst at the end:
The transmitting eyes don't have any 'information' about the direction you are looking from. So, the light has to be transmitted in every direction - a full half sphere. At best, you would see a tiny, dark glow far away.


5 years ago

How about a solar powered post?  With a system you face the problem of a system failure, one component goes bad or gets vandalized and the entire section goes dead. With individual independent markers having one damaged, run over by a distracted driver or something, will not have a large impact on the overall function. It will also be cheaper to replace only the damaged ones without having to do extensive maintenance on a system.  Its how something like an ant colony works. The individual has a function but is redundant in the number of others that can take its place. The loss of one has little effect on the overall functioning of the colony. The colony achieves its goal because of redundancy. With highway markers each marker is independent and so its loss will not effect the overall function of the markers as a whole. But tie them together into groups and systems and the loss of one in the group disables that group. Then you have entire sections that go dark with the loss of an individual.

We call then solar garden lights over here :-)

There you go - What seemed like a good idea perhaps isn't (Yet)

What about feeding a single bright LED to many Cats eyes! rather than an LED in each one. Mmmm

Many of the rural roads here in East Anglia already have powered cats-eyes.

I don't know if they are solar or mains, but they work even if you switch all your vehicle lights off.

Not that I have ever tried such a thing, officer!


5 years ago

Some of the most effective road markers and striping I've ever seen were made with a reflective paint with a high content of glass beads mixed in the paint (actually, a highly resilient urethane.)
Used in the centerline and shoulder stripe paint, it feels almost like continuously, low level lit lines.

So what's next? You should probably do some power calculations. Ignore the mechanical/cost implications of connecting hundreds of cats eyes by fibre and think.... how much light shines on a cats eye at present. If I can couple 100% of that light in to fibre, how visible will that be if I split it between 10 or 20 cats eyes further down the road?

Also, current cats eyes are reflective, you can have a facet facing each way making them useful in both directions. Wouldn't your design require a chain of fibre for each direction?

I think the idea of extending cats eyes further than dipped beams is a good idea. Might LEDs and copper cable be cheaper and easier?

Thanks for your response

Hard to evaluate efficiency - My experience with 100 mete roll of solid 1mm dia plastic fibre cable, (very cheap 50p/mtr or a lot less in bulk,) Is it can carry a white LED light end to end easily. So I would think that with a little simple optical lens at the start and end the light capture would be considerable.

If I share 80 watts (a dipped beam in the UK) between 80 cats eyes 10 meters apart Assuming 100% collection then I get a light of 1 watt over the next 800 meters. Easily viewable I guess at that range - So even with less collection it should be usable light.

You actually need very little light at night to appear very bright indeed.

The link in your next answer was a good find :-) I haven't seen any of these but I guess they are more expensive as they are more complex, Therefore have a limited use.

One advantage of my suggestion is that the cats eyes won't appear to flash at all any more then they do when illuminated by your lights anyway. They will just appear further away - Many times 80 meters if necessary.

All of the light from an 80 watt bulb doesn't go into the fibre though. It illuminates an area of about 4x10m, right? Of which your cats eye is approx (very generously) 0.01% that area?

Following up... apparently there are many places in the UK that already use active road studs. They currently use solar powered LEDs, other than in tunnels, when the shape of the road means that lanes aren't illuminated by headlights. The third post in this thread details the UKHA's stance/use on them: