I used to drive on a residential road to work that was also used by heavy trucks. The road was steep approaching a major intersection. The heavy trucks had wrinkled the asphalt so much that it rose 2 to 3 inches above road level at that intersection.
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jt:
Kind of like how my bed comforter ends up several inches one way or the other by the time I get up to use the head at three in the morning, or 45 degrees angled to the bed so I nearly bust my neck tripping over the corner thatâs halfway out across the floor 
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I would be concerned about the freeze thaw cycle with permeability. Much road damage and pot holes are caused by water freezing and popping the asphalt.
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Hence this-
The first attempt was abysmal. After the first winter it was completely disintegrating. Each successive attempt got better and better with the last formulation now well past the 10 year mark and still performing the same.
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storm drains need to be below the grade of the road for drainage. Manhole covers are laid by hand, the mason does what he is told for height, then the contractor has to set the machine right. Where it snows they need to be recessed so they donât catch the cutting edge.
I help design roads for a living. I can add something to this conversation and clarify a few things others have mentioned.
1.Patches can be made smooth with the surrounding pavement. The patch needs to be installed in the warmer months and by a skilled contractor. Concrete (PCC) is easier to patch. Asphalt (HMA) must be rolled and that canât happen with a small patch. The roller just rides on the old pavement around the patch. So asphalt patching, when done right means a larger area, or heating to the proper temp of the HMA already on the ground.
2.Cost of concrete vs asphalt pavement is highly dependent on which materials are close to the area of paving. Here in Iowa, we have lots of high quality limestone. So, PCC is the cheaper option.
3.Paving material choice has no bearing on longevity*. We have very harsh winters and very hot summers and floods and droughts. And we, in Iowa, have pavement that is over 100 years old - both PCC and HMA. Proper maintenance performed timely is the key.
4.HMA is more prone to shoving and wrinkling at intersections. This is due to heavier vehicles stopping hard and turning the wheels. Itâs known and accepted that intersections will need to be replaced more often and this is true even if made from concrete.
5.Freeze/Thaw is only a problem if water gets under the pavement. Water is the enemy of all pavement. Keep it on the surface and get it to the drains quickly. Install subdrains when constructing a road.
6.Manholes and intakes can be adjusted to match the height of the new paving. Newer designs make this faster and easier, but cost more when first purchased.
7.The recipes for both PCC and HMA intended for interstates are different. There are many mix designs for varying conditions, but traction on interstates demands special raw materials.
8.Municipalities have no idea what utilities are up to unless the utility is owned by the municipality. Utility companies are large and often it is difficult to find the right people to talk to when planning road work. Iâve lived here 30 years and my phone company has been purchased 5 times. The people who had first-hand knowledge of the infrastructure are not available.
9.Where bridges and other structures meet pavement, there will only be a smooth transition if conditions remain the same as when constructed (if constructed properly). Water intrusion may be a culprit. Insufficiently compacted subsurface will also be an issue. Sometimes, subsidence happens for reasons unknown. Geotechnics is not a perfect science.
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I generally find asphalt to be smoother than concrete. Concrete might be stronger but it seems more brittle.
Superb explanation. Thank you.
I remember some Brits wondering why we donât use Tarmac (tar) in the states. Because we have the sunshine here! Lol.
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Thanks for writing that up. Thatâs interesting information.
There are INDOT restparks here in indiana off the interstates that have concrete roads and some of them are absolutely ridiculous with the crumbling and chuckholes. They dont seem to do amy patches, can we not patch concrete roads?
As long as the patching level is proud of the existing surface, the roller will compact it to the level of the existing base, right? Trouble is, that takes time and if the âliftâ is greater than some amount, you wonât get the best compaction of the lower layers.
The bigger issue I see is that they dig some hole to fix something that is fairly deep. Then they backfill without compacting layers or lifts. So the patch is made level with the base but the substrates continue to compact over time, resulting in a dip where the patch is. I have seen some areas where they leave it unpaved for some time to let the cars and rain compact the base materials before coming back and patching the asphalt. That seems to work but requires periodic adding of base materials (stone dust) to keep it compacting.
True but the emphasis now seems to be local absorption versus sending all that storm water elsewhere for bulk treatment. I see requirements for semi-permeable paving in most developments for some time now. You design roads- is that a trend youâre seeing as well?
I see requirements for semi-permeable paving in most developments for some time now. You design roads- is that a trend youâre seeing as well?
Not here, no. We are guided by either IowaDOT standards (https://iowadot.gov/consultants-contractors/design/design-manual) or SUDAS (https://www.iowasudas.org/). Storm infiltration under the road is counterindicated. Infiltration, detention, retention are strictly guided and enforced. Biocells and bioswales are common. Overflows lead to local streams and typically we want to hold on to storm water for many hours before releasing. Release is slow so as to not overwhelm the creeks downstream.
It all works nicely on paper. It may even work nicely after construction. But then a new development will be constructed further up the watershed and create problems where there were none years before. Many places have full retention of 10 year storms which are held permanently in neighborhood ponds. Many municipalities then work with the Iowa DNR to stock these with large mouth bass, crappie, and channel catfish (which are so cute when they are small - they have spots and croak when agitated).
I know of 1 small parking lot at a county park that has permeable pavement. Itâs in a swampy area so I donât believe it will be much of a scientific experiment.
I like Des Moines. I have a story. I was sent to the army post one weekend for army reserve duty. Had a problem to fix. My BIL lived there at the time and he told me his story about trouble with the local police. No one believes me but one morning the police showed up and hauled him off to see the judge. He had an unpaid parking ticket. He was able to show the judge that he had the payment ready to mail in his suit jacket but forgot to mail it. He let him go.
Heâs dead now but thinking about it, itâs quite possible it was a more serious offense. I dunno but Iâm always careful there. They take things seriously down there.
Thanks for the detailed reply- much appreciated!
I was looking around to see if I could find more info on the experimental sections of Interstate around here and found this-
Other Pavement Concepts
Research is continuing into porous and permeable pavements that have the potential to improve safety, reduce runoff and diminish undesirable environmental impacts. Some noise-reducing pavements are based on a similar premise. Permeable pavements may be constructed as full-depth porous pavements or surface friction courses.
Full-depth porous pavements are constructed using specialized asphalt layers or Portland cement concrete surfaces that permit water to drain down to a specially constructed crushed stone base. This crushed stone base functions as a temporary stormwater storage area and allows the runoff to infiltrate into the sub-grade. While this design concept appears promising for low volume facilities and parking areas, the foundation needed to adopt it on larger facilities is not in place at this time.
Permeable surface friction courses such as Open Graded Friction Course (OGFC) permit water to drain from the driving surface below the tire-pavement interface. This reduces hydroplaning, tire spray and tire noise while improving skid resistance and visibility. Several types of OGFC have been placed on Interstate and limited access highways in Massachusetts.
For reference (the rest of us not road engineers :))
In my state, weâre currently dealing with pavement problems that are more severe than potholes, on I-80. There have been a series of sinkholes that opened-up over the past couple of months, and it has been almost like whack-a-mole with one sinkhole being repaired, and then another one opening up on the shoulder or in a travel lane w/in a few weeks.
The problem has long-ago roots, because that part of NW NJ was an iron-mining area in the 18th & 19th Centuries. While there are some maps purporting to show the location of the old, long-abandoned iron mines, the maps are not necessarily accurate, for two reasons: The presence of Hematite deposits made compasses very inaccurate, so even when mining companies tried in good faith to provide the location of their mines, their reported locations were frequently âoffâ to a certain extent. Then, there were start-up mining companies that ceased operations in short order, when they couldnât find sufficient quantities of iron ore, and those short-lived companies never reported their locations.
When I-80 was constructed, in the late '60s-early '70s, Ground Penetrating Radar was just becoming commercially available, and apparently nobody thought about using it when that expressway was laid-out & built. Now, they are using it, and every time that it looks like an end to road closures will be approaching, it seems that they discover another void underneath or adjacent to the roadway.
Funny, I live in a state with the highest nighttime Tornados in the USA, and it is those sinkholes that scare me the most⊠
Sink holes are your friend! When the tornadoes blow up you can crawl into a sink hole to get away from them!
A little (a lot) dark humor. I couldnât resist.
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I went through the ice once and it takes a while to believe in solid ground again. Storms are just a normal pass time but having the ground give way underneath you could cause lasting trust issues.