Stress on Roads

This is directly related to The Master’s column If cars go electric, how do we pay for highways without a gas tax?.

What few weighmasters I’ve talked with over the years generally tell me it’s the semi-trucks that tear up the roads, not the passenger cars. So I’m thinking little hybreds and electrics rolling down a road designed to handle semis with 34 ton loads aren’t costing much of anything.

That would depend on the answer to the General Question “Is damage to the road strictly about pounds per square inch, or is there something like stress going on as well?”

Something tells me we’re not in Vector-ville anymore, please dumb it down some if you please.

Just throwing a couple of other things out there: sometimes, gas taxes pay for new infrastructure, not mere maintaining existing infrastructure. It is reasonable to expect users of that infrastructure, even if they are driving electric cars, to help pay for it. Secondly, sometimes existing infrastructure wears out as a function of time (specifically, freeze/thaw cycles can wreak havoc on roads), and again, it is reasonable to expect all users to pitch in to pay for necessary repairs.

It appears that we are moving rapidly in the direction of all new high-usage roads becoming toll roads. Similar to Mexico, where there is only summary maintenance on pre-existing conventional highways, and very, very expensive tolls on nearly all new highway construction.

Just past the freeway on ramps you can see where trucks shift gears in the road damage. ore so next to on ramps with heavy truck usage.

Apparently wear on the road goes up with the fourth power of the weight (I assume the axle weight, not the vehicle weight).

But that can’t be the whole story. I see a lot of asphalt bicycle paths where there’s a push button to get the traffic light to turn green for cyclists and the asphalt right next to the button is heavily deformed, apparently just from the front wheels of the bicycles stopping all in the same place.

Yeah, it’s shear that’s the real killer. You can also see it at bus stops, where the asphalt is buckled from the buses braking and starting back up. Around here, they’re starting to install concrete in place of asphalt at all the bus stops, to mitigate this.

And it shouldn’t be surprising to see damage on bike paths, either. Bikes exert a lot more pressure than cars, and I expect probably more than semis, too.