The North Carolina Turnpike Authority has hired a national transportation firm to study traffic and tolls on the proposed Currituck County midcounty bridge, a project already studied several times and delayed for at least 17 years.

The study by Wilbur Smith Associates is expected to be finished by late summer or early fall , said Julia Jarema, spokeswoman for the North Carolina Turnpike Authority.

The bridge is one of the longest-running and most debated highway projects in state history. Dozens of state and federal agencies and elected officials have wrestled over the viability of the project since at least the 1970s. An early projected cost estimate was $39 million, with a projection in 1998 putting it at $87 million.

The Turnpike Authority now estimates the cost at $132 million for a bridge about 7 miles long. The current transportation improvement plan for 2006 to 2012 on the North Carolina Department of Transportation's Web site estimates a 10-mile-long bridge at a cost of about $118 million.

A report from the Institute for Transportation Research and Education at North Carolina State University recently estimated the cost of a 7-mile-long bridge at $156 million based on state estimates.

The bridge would connect the Currituck mainland to the county's Outer Banks, relieving traffic tie-ups along U.S. 158 and N.C. 12 and quickening hurricane evacuation, supporters say. The sound and nearby swamps could be damaged and neighborhoods degraded, opponents say, and the intersection of the bridge and N.C. 12 on the Outer Banks could create more traffic jams.

The state conducted a multi year study on the travel corridor from Barco to Corolla. Last year, in preliminary results, the state determined that widening U.S. 158 and N.C. 12 would relieve traffic better than a bridge would. But a local grass-roots group, Build the Bridge - Preserve Our Roads, paid for a study that determined that the bridge would be better and cheaper.

East Carolina University is conducting another study using $2 million from a federal grant.

A bill passed in August authorized the state's Turnpike Authority to plan and build a toll bridge over the Currituck Sound using private financing and contracting .

A quick estimate indicates that tolls would generate millions, but how long it would take to pay for a bridge would depend on how much motorists would pay. An average daily count of traffic crossing the Wright Memorial Bridge, allowing for all days and seasons, is 21,000, according to state figures. About one-third of that traffic turns north toward the Currituck Outer Banks and would probably use a bridge from the mainland to Corolla, reducing travel time by nearly an hour. If 7,000 vehicles, or a third of the average daily count, each paid $5, for example, that would generate $12.8 million annually. Some of the toll money would pay for maintenance and debt services.

The Wilbur Smith study will be much more involved. As part of the contract, the cost of the study will be determined when more detail is known, Jarema said.

The North Carolina Department of Transportation has turned the project and its prior studies over to the Turnpike Authority, Jarema said.

• Reach Jeffrey Hampton at (252) 338-0159 or jeff.hampton@pilotonline.com.