BISBEE — The number of proposed routes for the eastern section of a bypass on I-10 to shuttle vehicles headed for Phoenix away from Tucson has been dropped to four.

The revised routes were presented by Dale Buskirk, director of the transportation planning division for the Arizona Department of Transportation, during an hourlong presentation of the preliminary study by consulting company URS Corp. on Monday during a work session with the members of the State Transportation Board and technical advisory committee.

Buskirk also hit upon  some of the facts of the need for the bypass and the routes best suited to accomplish the goal of redirecting traffic around Tucson to Phoenix.

There is a recognized need to provide a corridor to relieve traffic congestion between the growing metro areas of Tucson and Phoenix, Buskirk said. Anticipated growth for both cities and the increase in truck traffic far exceeds the capabilities of the interstate as it exists today.

But Buskirk noted that such a massive project, which could entail construction of a few hundred miles of roadway, is only being planned for 20 to 30 years from now. There may even be two bypasses built — one to the east of Tucson and one to the west.

Construction alone could take several years and several billions dollars. Just where the money would come from is unknown.

One of the proposed eastern routes runs through the San Pedro River Valley starting at I-10 in Willcox then cutting north and west between the Rincon and Santa Catalina mountains to the west and the Galiuro Mountains to the east and joins back up with I-10 near Casa Grande. Concern to protect the fragile ecosystem and the San Pedro River has led many residents and environmental activists to merge to fight any road construction.

One such group is the Cascabel Working Group which has led an opposition movement since catching wind about the plan earlier this year. Some of the members attended the work session in Tucson.

“They dropped a couple of the routes … the route up the San Pedro River Valley from Benson, but otherwise little has changed since April. The presentation was mostly empty, except for a few statements about the length of the alternate routes, which confirmed what we already knew; namely that there is very little saving in mileage,” said Robert McClure, one member of the Cascabel Working Group who attended the work session.

The study determined the two routes through the two valleys would be around 135 to 144 miles long and would save 6 to 15 miles on a road trip to Phoenix.

According to the preliminary study, the routes through the San Pedro or the Araviapa valleys would redirect an estimated 14,500 vehicles by 2030 and 20,000 by 2050, said ADOT spokeswoman Teresa Welborn during a telephone interview on Wednesday.

ADOT estimates place truck traffic at 30 percent of all vehicles on I-10, and that figure is growing. The agency also estimates that one tractor trailer does the equivalent road damage of 9,600 cars.

The ADOT Web site shows a study map with 2005 daily traffic counts of:

• 13,000 vehicles on I-10 between the New Mexico border and Bowie

• 14,000 near Bowie at Highway 191

• 15,000 from Willcox to Benson

• And 30,000 from Benson west picking up more traffic as the interstate heads for Tucson.

Many in the remote area are wary of development that could occur once the highway is built and see real estate attorney and State Transportation Board Vice President Si Schorr as a possible adversary.

“My sense was that in Schorr’s mind the Aravaipa and San Pedro Valley routes are the most viable options,” said David Omick, who also attended from the Cascabel Working Group. “From the beginning we’ve all suspected land speculation as the real reason behind the bypass proposal.”

Another Cascabel member, Susan Newman, also questioned Schorr’s motives.

“Schorr’s advocacy for a bypass is the tip of an iceberg of real estate speculation, opaque by design, for which relieving traffic congestion in Tucson is a patent dissimulation,” she said. “I don’t care for conspiracy theories generally, but Arizona development politics is chock full of precedents for such nonsense. Get the public to fork out enormous sums to produce a much smaller windfall for a handful of people whose property will double or triple in value once the project is in place.”

Schorr responded in an interview Wednesday.

“At the public meeting I made it clear that it was necessary to avoid environmentally sensitive areas,” he said.

The I-10 bypass could have limited access with few off and on ramps that would prevent development from taking place along the new route to Phoenix, Schorr said.

A series of public meetings will be scheduled in November and December, Welborn added. The selected cities are Buckeye, Casa Grande, Marana, Tucson, Benson, Willcox and Safford.

As of yet, no dates have been set for any of the meetings.