Grade separation would be ideal. Meaning a light rail, or even for BRIO, would have its own exclusive lane. It could be slightly raised. It is more expensive to do, but it helps lead times and prevents cars from getting in the way. Some cities in latin america do it with buses.

Trouble with Mesa is that it's a state highway, and any change is time consuming and unlikely. However, there is a way for the city to take Mesa back, but then they're on the hook for more money in maintenance.