Repaving roads - why the wait?

Factual Questions
1

Partial rant, partial actual question.

They have been re-surfacing a patch of road near my house pretty much all summer. Well, it started not long after school let out, and they’re not done yet. There were HUGE chunks of time where there was ABSOLUTELY no work being done. Why? Other than the excuse of “we’re doing multiple jobs, and the paver isn’t available”? Once they strip off the top layer, do they have to wait a certain amount of time before putting down oil? Once the oil is down, do they have to wait before putting down blacktop? This came to a head this weekend. On Friday, they started putting the top coat on a stretch past a local grade school (didn’t finish). Meanwhile, they had oiled a much longer stretch. It rained all day Saturday and most of Sunday. There were numerous accidents on a 1-mile stretch because people didn’t expect the road to be slicker than during an ice storm. Someone took out a power pole. Well, they didn’t have time to put up a new one, so they had a crane out there holding it up. Someone spun out and put the dangling pole through their windshield. AFAIK, no fatalities, but the village actually closed down that stretch of road.

Enough of the rants. Serious question - do they have to wait a certain time between layers (oil, base coat, oil, top coat)? If so, why?

2

Basically it seems to be the low or most politically favored bidder for a project handling multiple jobs and taking it’s sweet time unless paid a premium for timely completion.

3

I’m a civil/environmental engineer who works for a public water and sewer utility. As part of my job I replace water and sewer mains. Following installation, we have to restore the road by paving. I have restored many millions of dollars of roads for state and municipal governments.

So there are a couple things going on here. If you’re doing any kind of excavation, like a water or sewer main installation, you have to backfill with the proper material in specified lift thicknesses. Then you have to do compaction tests on the backfilled material. We then typically pave with 2-4” of temporary pavement. The reason for the temporary pavement is because the best compaction you’re going to achieve at the time of installation is about 95%. If we were to pave right away, you would inevitably get settlement in the trench. So the owners of the roads (i.e. state or municipal governments) typically require us to wait 90 days before doing final paving.

After the settlement period, we have to re-excavate the trench down to the bottom of the required final asphalt thickness and repave in lifts. This might be as much as 9 inches of asphalt for final trench pavement. Sometimes it also includes restoring concrete road base (with rebar and dowels).

For a major roadway like a state highway, they then typically also require us to mill down and pave at least a lane, and sometimes curb to curb across the entire roadway. This typically consists of milling down 2 inches and repaving the required width so that there is no visible trench.

No “oil“ is required between asphalt lifts. No idea what you’re talking about there. The thicker the lift of asphalt, the harder it is to get it to cool in a timely manner as well as getting the required compaction. Plus the owner of the roadway likely has a max allowable lift thickness. Max thickness is typically 3 or 4 inches at a time. If they’re putting down multiple lifts at the same time, you don’t need to do anything special, but if a lift is left for longer than 24 hours, then you need to apply “tack coat,” which is a sticky asphaltic liquid that is sprayed onto the lower lift to help the lifts (i.e. layers) of asphalt adhere together. This is applied immediately before paving. You wouldn’t want anybody to drive on the tack coat. It would make a mess.

As for your timing question, companies typically use a dedicated subcontractor for milling operations so sometimes the milling may happen before the pavers can get out there. All government contracts include a time limit to finish the work. If they don’t finish in time, they’ll be assessed liquidated damages.

There’s not typically any penalty for starting and stopping the work as long as they make consistent progress. If a contractor disappears for weeks, we can direct them to proceed, and it will be reflected in their evaluation. And of course some contractors are better than others, but we are always required to award the contract to the lowest (i.e. cheapest) qualified bidder in a formal bidding process.

Again, we are required to award contracts to the lowest qualified bidder, and we give them a time limit to complete the work. Awarding a contract to the “most politically connected” bidder is strictly illegal. IME, these rules are strictly followed at my agency.

4

Thank you for this well formed and educational post!

5

Thank you for your reply!

The work being done is strictly re-pavement. OK, we all know that nothing is ever “strictly”. But, it certainly did NOT include new sewars or curbs. Scrape a layer off, fix a few underlying things (I don’t remember anything longer than maybe 20 feet, and I am not in the business, so I can’t tell you what they were doing in those fixes).

That’s exactly the type of thing I was wondering about. 90 days for compacting. However, I didn’t see any sewar/water work hapening along the route.

Again, not in the business, but they put up signs “Fresh Oil”. And you can tell they sprayed something on the roadway. This is northern Illinois, if it matters.

That might be it. Unfortunately, seems commonplace around here.

Again, thank you for your reply. TIL about paving!

6

Was it necessary to quote the entire post when replying directly after it?

7

Instead of repaving the road (or more precisely, milling off and repaving), sometimes they attempt to extend the life of the existing asphalt surface by seal coating with or without stone chips rolled onto the seal coating. The seal coating may be referred to as “oil” on highway warning signs.

8

My car went over a road being repaved.

It took several hours of hard work to remove all the tar.

Then I hired a pro detail the car. Buff it and wax.

There’s still tar on the underside.

Next time I’ll turn around and find a way to detour around a road being paved.

9

My street was dug up a year ago to replace a water pipe and then repaved. Now they are replacing a sewage pipe. The work started in June and they dug down around, I estimate, 10 feet. They are now closing the driveway to my garage every day and putting down plates after hours. Most of the road (the part not closed) is now gravel a couple feet below grade and you can drive on it. They are estimating finishing by the end of October. What a mess.

10

That’s the thing I always found perverse.

Take a seemingly OK street. Tear it up and lay one kind of pipe. Repave. Tear it up again to lay a different kind of pipe alongside the first stuff. Repave. Tear it up to install electric or cable or phone stuff. Repave. Tear it up to install gas lines. Repave.

I must say I see much less of that nowadays than when I was young. Are we better at project coordination?

11

For many roads you could easily halve the time by closing the road entirely and making people take a detour. Instead, many works try to keep half the road under traffic and work on the other half. You might experience stop/go signs, queueing and traffic delays, but you’ll initially be going over the old surface, and then driving on new surface until all the work is completed. The work is less efficient and takes twice as long, but you will be inconvenienced far less, but feel compelled to complain twice as much.

12

All true.

There’s another issue for work on surface streets rather than limited access highways. There are residences or buildings which front the construction area and often have no other access than that street. If it’s completely closed for rework, what do those people & businesses do about getting into and out of their addresses? What about police and fire emergency access to them? So keeping at least partial low-capacity access is far better than none whatsoever.

I learned recently that the technical term for this part of road reconstruction planning is called Maintenance of traffic - Wikipedia. And MOT planning is a major part of any significant road construction effort.

13

Aren’t all roads in Montreal under construction at all times? Last month I tried to drive about 5 minutes between my younger daughter’s McGill residence and my older daughter’s apartment off Sherbrooke. There were so many road closures I ended up driving over the mountain!

14

I’ve told this story before, but it’s not readily searchable-uppable. Not enough unique vocabulary.


A few years ago when I was condo president we experienced the reconstruction of a city park near our property. Which came out beautifully, but often involved a ~week of intense work followed by ~6 weeks of absolutely nothing happening. But it did eventually get finished.

IANA construction anything Guy, so I was curious about this ongoing sloth. I got to know the project supervisor who hung out in his little trailer on the (rare) days there was work happening. Eventually I asked him “I’m not complaining or busting your chops, but … What gives?”

He explained that the City must go with the lowest bidder. So these sorts of jobs are bid at barely or even below breakeven by all the construction companies. Who use these jobs as essentially “banks” of stored work backlog they can use to keep their crews occupied when there’s no better paying (read “commercial not government”) work available. The industry doesn’t pay people to sit around unused, and laying them off would result in them drifting away and being unavailable when you need them again a couple weeks later. So keeping them occupied, even on work that barely pays for their efforts, is still a net positive for the business viewed as a whole.

Of course the City knows this dynamic too. And writes the RFP at least semi-mindful of how fast they need / want the completed project versus how much they want to scrimp on costs versus how fully tasked the local construction industry is. And they set the contractual completion date accordingly.

In my park’s case, the City had no great urgency to reopen a park that had been neglected for a couple decades. So they gave a generous completion date and got the job done for really really cheap versus the quality of product delivered. They could have paid double and got the same work done promptly with crews working all day every day.


As a general matter I suspect roadwork has a generally higher urgency to complete construction promptly once started than do, say, parks. But there’s probably still an element of “cheaper or faster. Pick one.”

Net of course of the legit inevitable engineering pauses that @robby so thoroughly addressed.