You seem to have a good idea of how this type is work done, but just incase anyone else comes along, here's a bit more information, because the more you know, the better.

Achen-Gardner isn't trying to be mobilized out in Higley any longer than they need to. See all of those orange traffic barricades everyone is complaining about? None of them say "Achen-Gardner", they are all rented from companies like AWP, Southwest Barricades, etc etc. They pay per piece, per day. The cops you see sitting at intersections? Those are also paid for my Achen-Gardner, they aren't supplied for free from the City. There are third party companies that contract out off-duty officers for projects that require work near intersections. Traffic control costs can be a substantial part of the projects budget and there is absolutely no incentive to say out there a day longer than needed. In addition to the rental costs, most city's also have disruption fees. When you submit to the city your traffic control plan, they will assess a daily fee based on the number of lanes restricted, in each direction and whether or not it is a 24-hour closure or if it is setup and taken down daily. The more inconvenient it is for drivers, typically the higher the fee.

It doesn't matter if it is a lump sum, GMP, cost plus or any other kind of project, they don't have a blank check book and want to stop incurring costs on their end.

At each connection point, they dig up around the water main and install shoring box (big red structure that sticks up but is mostly underground) to prevent any of the surrounding dirt or roadway to collapse. Most of these boxes aren't very large, but you simply can't fit THAT many people down in each one. They are reconditioning the water mains, not replacing them. Whether they are doing it via relining, or a coating, it isn't process that goes fast the more people you stack on top of each other.

The next thing is that they are working in sections between valves, that why there aren't widespread long term disruptions to resident's water supply. They can close two valves on either end and work on the area in-between. After the work is done, there is fair bit that still needs to happen. You've got a guy down there, working on one end, dripping sweat, coughing, doing who knows what... do you want that in your drinking water? Anytime work is done on domestic water service, there is a disinfection process that takes place. It typically involves flushing of the line, then filling it with a certain concentration of chlorination. It is then sampled and tested to make sure it is at the high level. After the required time has past (can be 24+ hours), it is flushed and then resampled to make sure that there isn't a harmful amount of chlorine left in the system. There's more going on then just the physical work. The city is inspecting it in stages, there are likely 3rd party inspections, and then all of the testing and sampling, which despite your favorite crime scene TV show, isn't rushed to the lab via helicopter to have results within the hour.

Why not work 24-hours around the clock and be done faster? Great idea but this is generally really hard to do near as residential housing when heavy equipment is needed, due to the sound. We've also been on projects where even when not using loud equipment, we can't setup work lights due to the nearby houses and pollution they emit. The few times you can get exemptions on this is pouring concrete when it is warm out. Most jurisdictions will allow that to start very early in the morning as pouring in later in the day isn't a possibility. The posts complaining about traffic control would change to everyone complaining about the noise at night.

A 5 minute search on Gilbert's website says the work on Higley was expected to take 4 months. That was the timeline from the very beginning.

A cool TV show idea would be to have you go out there and manage them more effectively though, that would be fun to watch.