Photo of crosswalk lines distorted by tires action-reaction

[ezfzx]

TL;DR Summary

We've all seen these photos, but can't seem to find it on the Internet. Does anyone have one they took?

We've all seen these photos of the crosswalk (or other street lines) on the asphalt distorted when the driven tires of cars push back as they roll forward. (At least I'd like to think we've all seen them.)
I used to have one I took myself a long time ago.
But, for the life of me, I can't seem to find that one, or any like it now.
And the Internet search engines, which usually provide 100x more resources then I could ever use, can't seem to find one anywhere.

If you've got one, please post it. I'd love to use it in my lecture.

Thanks!

 

[berkeman]

I used a Google Images search for crosswalk paint lines crooked, and got a few hits. Here is one where there is a fair bit of damage to the painted lines (from asphalt cracks?), but it looks like there is paint displacement in the upper left of the image...

https://c8.alamy.com/comp/JDEHW9/crosswalk-painted-on-tarmac-downtown-new-york-city-usa-JDEHW9.jpg

 

[ezfzx]

Well, the image I was looking for showed a distinct bend in the lines.
When the power tires are on or just behind the line, as the vehicle accelerates from stationary, it pulls the low-grade asphalt back. Over time, the line painted on the asphalt gets pulls WAY back. I imagine it's very embarrassing for civil engineers who low-balled the paving.
But from a physics perspective, it's really cool as a demo for action-reaction.

If you've never seen it, it's hard to describe.
So, I created a really bad "fake" version of this effect ...

... just to give you an idea. The REAL deal is a LOT more impressive.

I think it was originally in a textbook or something someplace.
But there was a time when this was kind of common.
Not sure who's fault it is ... maybe it's cheap asphalt. ;)

 

[hutchphd]

Probably a hot summer!

 

[ezfzx]

Perhaps, but quality asphalt doesn't do this.
But it also happens with brick roads that have a loose foundation.
Here's a pic of the same phenomenon scanned in from the 12th edition "Conceptual Physics" textbook by Paul Hewitt:

This one is good, but not as dramatic as the cross-walk lines.
I'm going to claim "fair use" for the use of this image, with many thanks to Hewitt.

 

[256bits]

Perhaps, but quality asphalt doesn't do this.
But it also happens with brick roads that have a loose foundation.
Here's a pic of the same phenomenon scanned in from the 12th edition "Conceptual Physics" textbook by Paul Hewitt:
View attachment 274992
This one is good, but not as dramatic as the cross-walk lines.
I'm going to claim "fair use" for the use of this image, with many thanks to Hewitt.

The evidence for that is where?
Seems to me the stones were laid that way - some curves alongside the edge of the road and the narrowing of the road at the top.
I can see some displacement of individual stones, but not the whole structure.
A before and after comparison would have been appropriate from the author, and a more complete picture of the road.

 

[Halc]

Not a crosswalk, but definite deformation seemingly due to a vehicle stopping hard on a hot day.
Not at an intersection, so probably not from repeated force.

 

[256bits]

One would think there should be a 'hill' of built up asphalt in the lane ( there is to the side by the shoulder ) , and cracks in the rearwards direction and not just the forward, but pictures are difficult to decipher. It looks as if the road is sunken in that particular spot from a poorly laid bed.

 

[Lnewqban]

Summary:: We've all seen these photos, but can't seem to find it on the Internet. Does anyone have one they took?
...
If you've got one, please post it. I'd love to use it in my lecture.

Thanks!

Here you can find a list of common types of asphalt distress, as well as pictures:
https://pavementinteractive.org/reference-desk/pavement-management/pavement-distresses/

It could also be a case of improperly applied tape.
Copied from
https://en.m.wikipedia.org/wiki/Road_surface_marking

“The life of the preformed polymer tapes can vary based on the applications. If applied correctly, they can last between 4 and 8 years.
However, there have been cases where tape failures start soon after the installation. Conditions that may contribute to the tapes to peel off are the time of year of the installation that is too close to the winter, surface preparation, and workmanship.”

 

[ezfzx]

OK, my wife got tired of me talking about this, so she took this picture a few miles from our house.
Generally, these kinds of shots better when you're looking down the length of the line, but this is still pretty good.

https://www.physicsforums.com/attachments/275044

There were some I saw a few years ago where the distortion was REALLY extreme, like the lines were pulled back half a meter or more.

 

[ezfzx]

Doesn't really look like improperly applied tape.
Looks more like improperly applied road. :)

 

[ezfzx]

One would think there should be a 'hill' of built up asphalt in the lane ( there is to the side by the shoulder ) , and cracks in the rearwards direction and not just the forward, but pictures are difficult to decipher. It looks as if the road is sunken in that particular spot from a poorly laid bed.

Yeah, I've watched these folks put this stuff down, and I'm certain they try their best to make sure that it's all evenly supported underneath. But over the course of 1000s, if not millions of miles of road, there's bound to be some goof spots where the ground has settled leaving gaps, etc.
And I would venture to guess that asphalt, being softer material, is a tad more compressible than concrete.

I think there would be a build-up, but I think you don't see it because the surface settled.

Think of these spots as pot-holes that might have been (and may still become).

 

[Keith_McClary]

they try their best to make sure that it's all evenly supported underneath

Here they seem to just build the highway and wait for Mother Nature to show them where is the swampy ground or slumping hillside. We don't need no expensive geotechnical engineering.

 

[Lnewqban]

OK, my wife got tired of me talking about this, so she took this picture a few miles from our house.
Generally, these kinds of shots better when you're looking down the length of the line, but this is still pretty good.

https://www.physicsforums.com/attachments/275044

The link seems to not be working.

 

[ezfzx]

 

[256bits]

View attachment 275110

I responded with some 'scepticism' of the pictures given before, but this one really shows the effect.

I was looking for something such as in @Lnewqban's link of Pavement Distress - Corrugation and Shoving as a telltale sign - a perpendicular buildup or depression, but some of the obvious signs may not be there at all with all the continuous traffic flow.

 

[ezfzx]

I responded with some 'scepticism' of the pictures given before, but this one really shows the effect.

Yes, I suppose I'm surprised by how many people in this forum have NOT seen this effect ... a decade or so ago, these kind of pictures were all over the place ... some REALLY extreme effects were common. And now it's like these pictures have just vanished from the Internet.
It's a bit like someone asking "Who's Elvis?"
(OK, maybe that's a little bit of an exaggeration.)

Anyway, when teaching physics, it's nice to have a picture of a very real and tangible example to remind students what direction the forces are in.

It's important to emphasize, that this is the effect of a drive wheel ... the wheel on the axle connected to the motor, which it pushing against the ground to move forward.
The non-drive wheels are not powered and are basically pushed or dragged, and the forces of friction on those wheels are in the opposite direction.

Here's another photo that is equally impressive, of the wheel of a dragster as the axle is providing torque to the wheel, which is delayed in moved through the tire because of friction with the ground. The result is a bit of a shearing effect, which would rip the tire to pieces if it were not made so well.