Get ready, West Lawrence residents: The cars are coming.

Lawrence city commissioners at their Tuesday evening meeting quickly approved an agreement to spend $1 million in city funds to help pay for an estimated $17.2 million state project to build an interchange at Bob Billings Parkway and the South Lawrence Trafficway.

But commissioners spent considerably more time discussing what comes next: about 5,000 additional vehicles per day once the intersection opens, likely in late 2015.

“That’s what it will be right after it opens, and it will go up from there,” said Chuck Soules, the city’s director of public works.

But Soules also told commissioners that the city already has begun a study to determine what additional improvements may be needed on Bob Billings Parkway to ensure the extra traffic flows smoothly.

Soules said the city’s traffic engineering division is expected to complete a report by the end of the year providing recommendation on issues such as additional stop signs, new traffic signals, right-in/right-out only designations for some side streets, and possibly closing some access points on Bob Billings Parkway.

Commissioners heard from Julie Hack, who lives in a neighborhood along Bob Billings Parkway. She said she counted 60 access points — driveways and side streets — on Bob Billings between the SLT and Iowa Street. She said increased traffic will make it more difficult for residents to pull onto Bob Billings Parkway.

“I hope you have a plan in the works to slow down the additional traffic,” Hack said.

Soules said the city’s hope is to make traffic move smoothly on the major road, but he said the city won’t be considering traditional traffic calming measures like speed humps or narrowing of driving lanes.

But city officials acknowledged speed is a problem on some of the more wide open stretches of Bob Billings Parkway.

“When I’m going 45 on that road, there are people passing me by 10 to 15 miles per hour on a pretty consistent basis,” City Commissioner Terry Riordan said.

Mayor Mike Dever said there may be more traditional ways to deal with that issue.

“I’ve already heard a couple of commissioners mention radar and police officers,” Dever said.

Commissioners said they want staff members to give particular thought to how to handle safety issues on Kansas University game days. The new interchange is expected to create a major gateway into the KU campus for motorists coming from the west.

The state is expected to begin construction on the interchange project in the spring of 2014. The city previously had given preliminary approval to a deal where the city would pay about $1 million of the estimated construction cost of the project. Commissioners formalized that agreement Tuesday.

Douglas County commissioners are scheduled to formalize agreement to pay for $528,000 of the costs at their Wednesday evening meeting. The Kansas Department of Transportation will pay for the balance of the estimated $17.2 million project.