I can offer a possible solution:
First, a long and boring introduction to paving methods. When paving roads, a paving machine has a limit of how wide it can pave. Usually, on two lane roads, the paver paves from the edge of travelled way to the center, and then goes back and paves the remaining half. On roads with more than two lanes, or on busy divided highways, the paving machine will pave one lane at a time. If you have never watched a paving job (and I’ve watched far too many :rolleyes: ): the trucks back up to the paving machine, and raise their truck bodies to dump hot mix into the hopper of the paving machine. They then move ahead in tandem (like some huge, noisy, smelly, copulating insect), the truck delivering mix into the paver, and the paver spreading the mix behind to a specified thickness. Big rollers follow the paving machine, compacting the mix as it cools. When the truck is empty, the truck pulls out of the way. The paver has enough mix to keep going until the next truck can back up. Once this operation gets going, the paver can cover quite a bit of ground in a short period of time.
The trouble here is that if the paver moves too far ahead, and/or if too much time elapses before the paver goes back to do the abutting lane, the pavement will have cooled substantially at the beginning of that “pull”. This creates what is called a “cold joint”. There are two types of paving joints; longitudinal joints (between lanes, follows the direction of traffic), and transverse joints (perpendicular to travel, usually where the paver ended for the day). Cold joints are undesirable, because the mix has cooled and compacted, and there is less chance for the new pavement to interlock with the previously placed pavement. Paving contractors usually have to balance the desire to just keep paving with the necessity of backtracking to keep a hot joint.
This can be a problem even in the two lane roads mentioned above, but is especially a problem where paving takes place on highways that are still in operation. As you might expect, the paver and the highway officials only want to take one lane out of commission at a time, so miles of pavement might be placed in a day (or night). The next day the next lane is placed, but the joint between has cooled and set, and there will always be a noticeable joint between. This can be helped a bit by soaking the cold edge with asphalt emulsion, and then spreading sand to help seal the edge, but a hot joint is still preferable.
As hinted above, night paving is now more common on the busier highways, but it also allows gaps in the pavement to go unnoticed.
Over time, especially in colder climates, water works its way into the joint between the lanes. Freeze/thaw creates the potholes.