Just to bring this up to date. Construction is finished on the north end of town, but it can still be quite a slow trek south on US 191 into down, esp. on Friday afternoons. But most days do get busy as everyone returns to Moab from their daily adventures.
If you are visiting Arches, make sure you you get your reservations on recreation.gov three months out from when you want to go in. Reservations are released in one month blocks three months from the first of the month that you want to visit.
https://www.recreation.gov/timed-entry/10088426