From a stopped position, starting at a low speed, as soon as my tyres cross the white painted lines, my steering wheel seems to shake for a moment. This happens regardless of the weather (rain or shine), temperature or car I’m in. I’ve noticed the phenomenon when crossing a painted white line, denoting lanes.
Why do my tyres seem to skid on white painted lines?
Years of build-up of white paint thereby elevating the painted surface above the tarmac and providing a “washboard” affect?
I live on a residential city corner. I lead a boring life, and almost daily spend time looking out the window, calculating the percentage of drivers who actually stop at the stop sign. No, I am not kidding.
ETA : The percentage is ludicrously low - like 1%. Nearly everyone rolls, a very few ALMOST stop, and that 1 in 100 actually stop.
Anyway, I notice that almost all of the cars make a little squeak when they roll over the painted “STOP” on the street. Fast, slow, dry, rainy, almost all of them make the noise.
I’m guessing it’s a traction issue…
Joe
Why is the OP font different? Or is that just me?
My guess is that it’s paint, and you can’t get good traction on paint.
If you’re not accelerating or braking especially hard, you shouldn’t lose traction. My guess is that it’s simply a “wobble” caused by crossing the ridge of paint at an angle, which deflects your wheels a bit. I notice this effect a lot when cycling - double yellow lines at the sides of urban UK roads are a particularly bad culprit as a bike wheel fits between them and can “tramline”. When roads haven’t been resurfaced for some time, but the lines have been repainted several times, as Leaffan says, there can be quite a high ridge.
There are several types of painted lines. Those that separate lanes are not very thick because they are not supposed to be stepped on much by vehicles.
The zebra lines on pedestrians crossings on the other hand are made by a very thick, hard-wearing kind of paint because not only they are ran over by cars constantly, but cars also accelerate and brake on them which wears them down very quickly. Maybe these things are not paint at all. They look more like strips of plastic glued on the tarmac.
These things are very very slippery. The first thing you learn when you ride a motorcycle is to avoid painted lines like hell. Some newer ones however look like they have a anti-slip cross-hatch texture on them.
Not just you. I also agree with the second line of your post.
I’ve watched them repair the stop line in front of my house several times - they use a machine which pours a hot, viscous plastic on the asphalt. The plastic cools and hardens within minutes. The roads guys take a handful of glass beads and throw it on the plastic before it cools, which makes it very reflective (for the first week or so, until all the beads get worn away).
I wouldn’t say the first thing, but you’re right. FWIW, “road snakes” or “tar snakes”, the lines of tar they use to fill in cracks, are especially slippery as well. It’s most notable at temperature extremes, and they’re fairly stable between, say, 45 and 90 Fahrenheit.
So, yes, a lower coefficient of static friction is a likely culprit. The static term can be a bit misleading, but in normal operating conditions, the bottom of your tire (i.e. the point in contact) is not moving with respect to the road. When the term becomes kinetic, that’s because your tires are locked up, or skidding, and the bottom is moving with respect to the road.
Because anyone can choose what font they want to use in their posts. Or size. Or color.
I knew we could pick colors, I didn’t know we could pick fonts.