In the Cleveland, OH area, they are rebuilding portions of Broadway Ave. Like in many rebuilding projects, they scraped away the top portion of the roadway, then removed more down to gravel. Then they rebuilt the roadway.
What confuses me is this… in some areas, they used concrete all the way to the surface - for example there is large section that goes under a viaduct that is concrete across all 5 lanes for about 1/2 a city block. In other areas, they only used concrete “underneath” and then put blacktop (asphalt?) to the surface. In some areas, these concrete top and asphalt top areas are inter-mixed, with the concrete top area only being one lane for perhaps 50 feet or so.
I can understand choosing asphalt or concrete for your roadway for different conditions - the concrete is going to last much longer than the asphalt. But why differences in such small areas, like a 50 foot section for only one of the lanes? This isn’t even in a “high” traffic area, like a driveway or an intersection - it might be right in the middle of a block in front of a business or a vacant lot.
There is probably some problem with the stability of the underlying surface. Normally you put asphalt on top of compacted gravel and earth, not concrete. Asphalt has no real strength of its own, it is basically compacted gravel and tar. It resists compression, but if the material under the asphalt fails, the asphalt fails. Asphalt can last as long as concrete if it is well supported. Asphalt doesn’t nomally fail unless the supporting structure washes away due to something like a drainage problem. If the supporting structure collapses or washes away, the asphalt basically fails from below, not from above.
I may not have been clear in the original message. The entire rebuilt roadway has concrete as a base above the compacted earth and gravel. The difference is between some areas being concrete all the way up to the surface of the roadway, or in only being concrete underneath, with asphalt on top.
I will check tonight when I go thru the area again - I believe at least one of the areas that is concrete surrounded mostly by asphalt IS a bus stop. Not sure why that would need concrete though.
There’s a couple of sections of Bayfield St in Barrie, Ontario, that have concrete surfaces. These are mostly in places where traffic starts from standing going uphill, and I suspect it’s because the forces of vehicles starting off were repeatedly distorting and tearing the asphalt surface. Google Maps link. Edit: bus stops often have problems with the bus tires forming bus knuckles.
Another factor might be location. Bridge underpasses and overpasses. The underpass has height limitations so a repair will usually include striping down to the soil and rebuilding. The bridge has weight limits so you just can’t keep packing on new asphalt without an engineering review.
The one spot I was thinking of I was able to confirm is a bus stop. I recall there being something similar to a “bus knuckle” at this location prior to them starting the rebuild. This may be the explanation. I will see if I can check the other small concrete areas and see if they correspond with bus stops.
I’m in Ohio as well so that’s why I suggested it might be the stops. It may be a ‘best practices’ thing done by various municipalities and ODOT for heavy vehicle traffic locations (in Ohio at any rate).
Several roads here in San Antonio are all asphalt except for concrete patches at bus stops (the patches are about five times the length of a bus, I’d say). The concrete isn’t nearly as smooth as the asphalt, so when you drive over it your feel a rhythmic thump-thump-thump feeling through the car. I try to avoid those lanes.
I did more checking - many of these concrete sections surrounded by asphalt ARE at bus stops and are about 5x the length of a bus. However, I did notice a number that did not appear to correspond with bus stops (unless the signs marking bus stops had been taken down for the construction). Still, this seems the most logical conclusion for their purpose.