The community likely will get less bang for its buck if it builds the final leg of the South Lawrence Trafficway south of the Wakarusa River, a traffic consultant hired by the city and county said Thursday.

Instead, building the road through the Baker Wetlands – north of the Wakarusa River – will do more to alleviate traffic congestion on 23rd and 31st Streets, said Jim Tobaben, a traffic engineer with Lenexa-based Parsons Brinckerhoff Quade & Douglas.

“If you move it south of the river, you will see less of a benefit,” Tobaben told members of the Transportation 2030 committee, which are working to create a long-range transportation plan for the county. “More traffic will stay on 23rd Street.”

Tobaben presented preliminary traffic models that showed by 2030 that a wetland route for the trafficway would take 35 percent of the projected traffic off of the portion of 23rd Street that is west of Haskell Avenue. A route south of the river would take 28 percent of the projected traffic off of the same stretch of road.

The difference was less pronounced for other sections of 23rd Street, however. A wetland route would reduce projected traffic volumes by 11 percent on the portion of 23rd Street between Haskell and Louisiana. Under a south-of-the-river plan, it would reduce volumes by 7 percent.

Tobaben said the models show that fewer residents would use a route south of the river, which means they would continue to use 23rd or 31st streets.

For some transportation planners, though, the difference between the north and south routes wasn’t much, given the amount of controversy building the road through the wetlands would create.

“It seems pretty marginal,” said Grant Eichhorn, chairman of the Lawrence-Douglas County Planning Commission. Eichhorn has been trying to revive a plan to build the trafficway south of the Wakarusa River in exchange for expanding the current 31st Street.

The committee, though, didn’t take any position on whether to endorse a wetland route or a south-of-the-river route for the trafficway. But members said they will before year’s end.

That’s when the Transportation 2030 plan is due to be turned into federal officials. Whichever route is left off the plan will be ineligible to receive federal funding. Federal funding is expected to play a role in the completion of the trafficway, which is estimated to cost $120 million or more.

Technically the community’s Metropolitan Planning Organization – which is composed of the same members that are on the Lawrence-Douglas County Planning Commission – will grant final approval to the Transportation 2030 plan. City and county commissioners, even if they disagree with the route selection, don’t have the ability to overrule the MPO, according to federal statutes.

Tobaben, a former Kansas Department of Transportation traffic engineer, stressed to the group on Thursday that completing the trafficway was an important piece of Lawrence’s transportation puzzle.

“I think a four-lane South Lawrence Trafficway would solve the majority of your east-west traffic problems,” Tobaben said.