Safe Speed Forums

Youve hit the nail on the head with the last paragraph precisely!
Varying levels of grip interspersed with no grip as the tyre isnt even in contact with the ground.

I have a wee hypothesis.
I reckon that at certain speeds, dependent on car size/weight that a situation could occur with these markings that can completely defeat the ABS system on a car.
I believe that when the car is at just the right speed, and the markings are just the right (or plainly wrong) distance apart that a harmonic/co-incidal type effect could occur that tricks the ABS into completely removing braking action.
The same kind of effects with ABS on ice can be observed as the ABS continually relieves pedal pressures in an attempt to slow the car with unlocked wheels. The result of braking on ice is just what we would expect then, a very long stopping distance compared to a dry road.
But, on a dry road, thats the last thing we need as grip is there in shedloads.
But the ABS system dosent know that, it only sees rotational differences between wheels as they rotate and change from ridge to ridge on these "safety" speed bars and "safety" red tarcrap.

I think its entirely feasible that such an effect could be observed and im pretty dammed sure ive encountered it.

Now to convince the authorities of their lack of wisdom huh?

My local authority has had the wisdom to put down 6ft wide strips of red stuff for about 100m coming up to a 30mph zone. Why I'm not sure. The problem is it's in a 60mph zone going down a steep gradient with a 90 degree right at the bottom. You therefore have cars braking quite hard to slow down for the turn with different amounts of grip kicking in every few yards. How this makes anything safer eludes me.

I've read and understood your post. What I don't understand is why your abs is even activating. I've been over these bars braking hard, braking soft and never had it happen.
If you're using "normal" braking force then is it possibly a tyre/shock problem?
I've no other suggestions but if it were me the car would be going straight to a dealer for a once-over.


yes mine most certainly can, that's why I do at least one advanced course each year as well as several track days (ok, they're mainly for fun but it's good to know how the car handles on the limit).

Deffoo not a shock or tyre problem. Theyve been replaced for bridgestone potenza SO1's all round and the car has persect manners everywhere else.
Front and rear springs and shocks have also been replaced....its one of the first things i did when i bought the car....ride too soft and wallowy etc.

Agree about doing a trackday, its good to know just what it is youve got hold of.
For now though im more than happy to leave the abs off and brake safely without its intervention, it pulls up ok even from very high speeds with no fuss or drama.

Id still be interested to know how widespread this problem is though, it must surely be the cause of some crashes.

I wonder what this stuff does for tyre wear!

What about those yellow strips that you often see on 70s when approaching a roundabout, and sometimes on a motorway slip road?

They get closer together as you get nearer to the roundabout and are designed to make an idiot think that they are not slowing down as much as they think they are. Given the general poor quality of UK road surfaces this plainly doesn't work.

However, if you actually look at one of these from a distance, it looks like the road is stretching off further into the distance than it actually is, and in my experience this effect catches more people than the intended effect, causing people to travel at a higher speed for much longer than they would have done normally.

They also tend to be on slippy yellow paint, so if we take the first post of this thread as fact then we have a situation where people are tricked into approaching a junction too fast, and then they cack their pants, brake hard and their braking system is tricked into working at reduced efficiency, all while heading towards a roundabout at 70mph.



As an aside, I hate councils that use that red grippy stuff as if it were some kind of highlighter pen. Many SC A roads in cheshire have a strip about a foot wide highlighting the centre line in sections where there is no overtaking or only overtaking in one direction.