TUCSON, Ariz. (AP) — Arizona transportation officials will continue planning for a proposed Interstate 10 bypass around Tucson and Phoenix but have dropped consideration of possible routes through an environmentally sensitive valley east of Tucson.

The state Transportation Board on Friday unanimously approved a motion that includes abandoning study of two potential San Pedro River valley routes that were among five corridors being studied for a bypass allowing traffic to skirt Tucson.

Some opponents of the project yelled criticism after the board’s vote, with a few vowing that a bypass will never be built.

Supporters say bypasses around Phoenix and Tucson are needed to handle the state’s long-term needs, in particular to avoid traffic bottlenecks in the two metro areas. They’re intended to allow cross-country trucks and other long-distance traffic to skirt the sprawling cities.

Including both legs, the bypass would extend appropriately 250 miles, extending from west of Phoenix in central Arizona to east of Tucson in southern Arizona.

Opponents say a bypass is unnecessary, too costly and argue that some routes would do serious environmental damage to sensitive areas, including riparian habitat in the largely undeveloped San Pedro River Valley between Benson and Mammoth.

It makes no sense to destroy sensitive areas with development, said Sierra Club representative Sean Sullivan. “It’s a waste of taxpayers’ money. We need to start planning our growth in a better way.”

Felipe Zubia, the board member who made the motion that continued the study but dropped the two San Pedro routes, said he agreed with criticism of those corridors. He said they would be environmentally damaging and not cost-effective because they wouldn’t divert enough traffic from I-10’s Tucson segment.

However, more study of long-term traffic needs is warranted, so the planning process shouldn’t be stopped, Zubia said.

S.L. Schorr, the board’s president and the member who originally requested the bypass study, said continued planning should include surveys of I-10 users, including those who would use a bypass.

“You cannot get hurt by planning. You can get hurt by not planning,” said Schorr, a Tucson real estate attorney.

With Friday’s board action, one of the three corridors still under consideration to avoid Tucson would connect with I-10 near Willcox and proceed northwesterly through the Aravaipa Valley before reconnecting with I-10 in Pinal County at or near the junction with Interstate 8.

A fourth route would take the bypass slightly to the east near Safford.

The other remaining corridor still under study to avoid Tucson would circle it to the west by traversing the Avra Valley and connecting with I-10 north and south of Tucson.

The Phoenix leg would connect with I-10 in Pinal County and again west of Phoenix.

A study commissioned by the state and submitted to the board concluded that the proposed bypass appears to be necessary to handle traffic needs and is technically feasible, but would be costly and lacks a funding source.

Building the entire 250-mile bypass route would cost between $6 billion and $8 billion, the study said.