ADOT is testing a new method for merging on I-10 near the Tucson area. It's called the "Zipper Merge" and it's designed to cut down on congestion by allowing drivers to utilize more lanes for a longer period of time.
Drivers will now wait to merge till they get closer to the restricted area, and then take turns merging into the other lane. There are signs on I-10 between S.R. 83 and S.R. 90, letting drivers know when to merge through the construction zone.
Although it may feel like you're being rude to the other drivers at first, ADOT says they've already seen less congestion on this portion of the freeway. Watch this video from ADOT, that explains exactly how the "Zipper Merge" works: