https://azdot.gov/planning/transportation-studies/riggs-road-traffic-interchange-sr-347
https://azdot.gov/projects/central-district-projects/john-wayne-parkway-sr-347-improvements-smith-enke-road-sr-238-to-maricopa-city-limits
At least there is some recognition that SR 347 is going to have to be improved, though it remains to be seen whether or not either Maricopa County DOT or the Gila River Indian Community will widen Riggs Rd. to 4-lanes between SR 347 and I-10. Or, for that matter, try to improve Casa Blanca Rd in that area as another way to access I-10.
Now to be fair, the original developers of the instant City of Maricopa (in Pinal County) had a decent sense that the new city will maintain good property values due to large-scale development being blocked on 2-3 sides by two Indian reservations. But my goodness; having 50,000 of the estimated 66,300 residents of the city on SR 347 on a daily basis...
This stretch of road really needs a complete overhaul because of the volume. I do wonder just how much of the lack of improvements is because of the rocky history of how friendly ADOT and the GRIC are. That was the biggest hinderance on touching I-10 across the reservation, which is only now being planned for widening (about 20 years too late). Also there was a lot of bad blood over the South Mountain Freeway. In reality, 347 needs to be full limited-access highway from I-10 all the way down and at least 3 lanes in each direction. Note that these two studies only focus on basically two small segments at the northern and southern ends, not for the portion crossing most of the reservation. A very small band-aid on a very large need.
I agree, a lot needs to be done, but the Riggs interchange is the biggest priority right now. They timed the signal as best they can but with the amount of cross traffic it just causes too many backups on 347 at rush hour. The Casa Blanca Road further south causes some too, that's probably the next issue after Riggs.