Why not do all work at night? Here are some reasons

By David Rookhuyzen / ADOT Communications

It’s a common question we get on social media: Why isn’t all construction done at night?

Night work does have the advantage of happening when it will impact the least amount of traffic. Around the Phoenix area especially, ADOT tries to schedule work on major freeways for nighttime or the weekend to limit the impact on drivers commuting to and from work.

Jesse Gutierrez, deputy state engineer for operations, said ADOT schedules all the work it can to happen during overnight hours, but there are certain factors that can require roadwork during the day. Those include:

Type of work: Some construction such as bridge-forming and abutments, which Gutierrez said involves intricate carpentry work, needs adequate light to be done well.

Temperature: Colder overnight temperatures can preclude certain work. For example, national standards for paving say it can’t be done below a certain temperature because the asphalt sets before it can be properly compacted. So overnight paving during fall, winter and spring months isn't possible. Winter paving in northern AZ is not even possible during the day.

Noise: Whether it’s urban or rural work, if it will be done near housing developments ADOT has to consider daytime work to minimize the nighttime noise for nearby residents.

Logistics: Practical concerns, such as the extra cost of running lights or having a paving plant open in the middle of the night, have to be taken into account.

Scheduling: Often, working during the day will get the project finished sooner. If a contractor says work can be finished after 100 days of night work or half that during the day, ADOT likely will opt to get a project over sooner to reduce the time that drivers will have to go through a construction zone, Gutierrez said.

Safety: The safety of construction workers is paramount. While there are fewer drivers at night, reduced visibility for drivers and workers must be considered.

Before a project starts, ADOT and contractors will go over all these factors to decide what work can be completed at night and what will need to happen during the day.

“We try to get the biggest value with the least impact to the public,” Gutierrez said.