The Maricopa Association of Governments is planning for a long-anticipated population explosion with new freeways and highways in metropolitan Phoenix that would serve an area larger than Delaware and Rhode Island combined.
The association envisions 400 miles of new highways and 320 miles of rail track to support millions of people projected to move into the desert largely south and west of Phoenix by 2050.
The plan would double the current highway system, create a commuter-rail network looping around the southern mountains and add a line to the West Valley to handle the projected 8 million population.
The Maricopa Association of Governments, or MAG, estimates it would cost $60 billion to build.
MAG's Regional Council is set to approve the concept this week.
The Hidden Valley Framework Study maps a new interstate looping to the south and west around the Valley, with new freeways connecting to the West Valley's Loop 303, Interstate 8 to the south and other new highways. The new interstate would divert truck traffic around Phoenix, serve growth and ease traffic through downtown Phoenix.
A separate plan envisions a second bypass taking Interstate 10 traffic near Casa Grande to the East Valley near Superstition Vistas by Apache Junction.
Critics question whether the economy would be strong enough to lure the projected population and whether sufficient water or electricity would be available.
But MAG says that without a plan, rapid development would overwhelm highways. They also contend long-range plans for roads for nonexistent cities don't foster speculative sprawl, but rather anticipate what's in the works.
The Arizona Department of Transportation next month will unveil a long-term blueprint for the entire state. The agency's director, John Halikowski, calls its scope breathtaking.
"Arizona is poised at the crossroads to decide what economic future it holds in store," he said. "I see it as a very bright future if we plan it right."
This fall, MAG is to complete a long-range blueprint for mass transit that envisions a commuter-rail loop in undeveloped desert, paralleling the new interstate and connecting with freight track through Phoenix and Tempe.
ADOT is incorporating work by MAG and other regions to map long-range transportation projects statewide.
The two-year effort is aimed at handling 16 million Arizona residents by mid-century.
Arizona's recent short-range population forecasts proved optimistic. Now, in the midst of an economic slump that burst Arizona's inflated housing market, some are skeptical about the population projection.
Planners say it may take longer than expected, but it will happen.
"I'm very comfortable with those projections," said Jim Zumpf, ADOT's project manager for the statewide planning effort. "Knowing they are coming we have to plan for that or else face gridlock and air-quality concerns."
Advocates of mass transit and compact growth say ADOT and MAG are thinking ahead.
"You could put your head in the sand and hope people won't come," said David Schwarz, president of the Friends of Transit. "I think you have to recognize that they will."