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Concrete pavement over a culvert

I walked along a drainage channel this afternoon, crossed Chavez, a busy street, noticed that 15 feet of Chavez’s pavement over the center of the drainage channel is concrete; it’s asphalt elsewhere. The channel is much wider and there’s no support in the middle. Why was this bit concrete? This portion of the drainage channel is dirt.

Not really able to picture what you are describing. Could you upload a photo?
Concrete poured over culverts is self supporting, whereas, to my knowledge, asphalt is not.

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Maybe… concrete culvert pipe laid down to let the road pass over, concrete poured over to supoort traffic.

Asphalt is a flexible surface that must be supported by a solid foundation. That is why asphalt highways have a concrete base, not a gravel base.

In the south they do…not up here in the north. Ours is very compressed gravel base about 2-3 feet thick.

Must be a solution to the freeze-thaw expansion.

My Ohio highway experience is when any major highway gets re-paved, they are done in concrete with a gravel base. Once the surface of the concrete starts to spall, they lay down an asphalt cap.

I lived near a recently re-paved highway for a few years done in concrete. It was NOISY as heck in the winter when the leaves were off the trees. We were less-than-patiently waiting for the asphalt cap to be added to reduce the noise.

A number of years ago, a ring-road got built in the Phoenix area all in concrete. Concrete holds up better than asphalt in the desert heat. The noise was a huge issue with the locals so they sprayed a coating that looked like asphalt seal coat on the road to quiet things down.

Maybe they bridged the gap over the creek with a reinforced concrete plate. The steel could be completely within the concrete slab.

Strength, concrete can be reinforced, rebar doesn’t work well in asphalt.

It takes at least 60 feet to traverse the culvert; the concrete bit is only 15. Nothing is under the concrete to hold it up.

There’s no pipe: it’s open unfinished dirt in this stretch.

The gap is 4 times wider; nothing holds up the concrete part.

Wanna bet? The law of gravity is final. If nothing is holding it up, it would not be up.

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There’s no extra support under the concrete part.

In the village adjacent to us concrete drive aprons are prohibited due to plow damage. A corrugated metal pipe is typically used under asphalt.