Standard washboard - Brake test surface

I'm in Huntsville, Alabama. Do you know of a place that this is currently going on?

 

Actually, what should work better than the "washboard" rough surface is the step/dip from the higher to lower section. Should trigger ABS immediately under moderate braking. It's like going off a 1.5" dropoff.

 

But this doesn't sound like what the OP is talking about. If it's the regenerative to friction braking transition, then all you need is a small patch of road imperfection (or the step/dip) to trigger it, not an entire length of rough surface washboard. It sounds like the OP is talking about testing the hypothesis that the brake somehow fails while riding on a strip of rough surface.

 

Bob, you have a warped sense of "opportunity". :madgrin: Reminds me of a podiatrist who was helping out at a footrace.

I help out at an aid station at mile 44 of the 100 mile Western States footrace from Squaw Valley to Auburn in California. One of the functions at this aid station is a medical evaluation of whether a runner is in adequate condition to continue, or needs to drop out. The early runners get a 10 second weigh-in, maybe a fillup of their water bottles, and off they go. About 4 hours later, they start coming through in, ah, more challenging condition.

One year there was a podiatrist who came with several of his students. In preparing the students for the experience, he mentioned that they would see some really good blisters that day. Nothing like the everyday blisters that doctors see in normal practice, but really challenging ones. Lots of them. And the ordinary practice of cleaning, bandaging, and recommending several days rest wouldn't cut it that day. The runners wanted to be patched up well enough to run the next 56 miles. If that meant cutting holes in $100 running shoes, so be it.

Like I said, real opportunity. Most of the aid station people thought of it as emergency care, and just didn't see the opportunity aspect. I guess if your business is blisters, then big juicy ones are nirvana.

Ok, :focus:. I just couldn't pass up observing that most people's disaster is opportunity for a few, ah, scientific minds.

 

Ah, well, usually the ground down edges of the road aren't all that similar to washboard - the road surface is usually smoother. More of a "very rough sandpaper" texture than washboard - unless they use significantly different machines in AL than CA before prepping roads for repaving.

 

This is exactly the type of roadwork that triggered my first experience with the ABS scare. I was driving along at about 35 mph approaching a stop sign, so was gently pressing the regen braking. As I approached the stop sign, I noticed that they had been working on the roads, and the patch right in front of the stop sign (and where I would apply more pressure to the brakes) had been dug out, and ramped down to the completely cleared away pavement. (like the bottom right side of your picture)

Perfect testing grounds, especially at that drop-off point!

 

My experience with Pearl (GII) is it's the "down" that triggers it, not the "up" part of the discontinuity. So a widened crack across the direction of travel. In fact, that is exactly where, two years ago, I first experienced it. Of course, it was just before a light at a "T" intersection with one of the busiest roads in Edmonton. If you didn't stop you would get clobbered at 70 km/hr on the drivers door. I never had a problem, as I don't leave my braking to the last second, but it was still unnerving, at best.

In this case it was a 5" wide crack about 3-4" deep across the road. Only the one, that's all it took. Washboard on gravel will also do it, but it varies in "wavelength" and "amplitude" a lot. Each instance of washboard is different. I've even experienced it on "washboard" on pavement, caused by hard braking by vehicles when it was hot over poorly laid ashfault. But I didn't stop to take measurements of it.

 

Go find some railroad tracks - usually the bumps combined with the slick rails will incur enough wheel slippage that ABS will kick in. Even easier if the tracks are wet.

 

Sounds like regen to friction braking transition, triggered by some imperfection in the roadwork. Really nothing different from going over a pothole. This isn't a separate issue from what we already know.

 

Yes, I realize that. I was just pointing out that the photo that Bob posted would be the perfect place to run his tests.