City buses can and do take Lawrence children to school. But officials said Wednesday formal transportation cooperation between the city and school district may be impossible.

Federal law prohibits the city from adjusting bus routes to serve schools, said Public Transit Administrator Karin Rexroad.

“We by law cannot be in the school charter business,” she said. “The service we provide to a school happens because it works with our existing routes.”

School board members Austin Turney and Jack Davidson on Monday said the district should explore collaborative opportunities with the city’s bus system. State budget cuts have forced the board to consider eliminating free bus service for students who live closer than 2.5 miles from their school; that move could save the schools $435,000 a year. But it could cost as many as 1,800 students a bus ride to school.

“Whatever we do, there ought to be a serious attempt to see how many of these children could use the T,” Davidson said. “Many of those routes go right by our schools.”

In fact, school officials are encouraging students to use the T but only for summer school. The city prepared a two-page handout to help summer school students use the T to get the class, but the district has no plans to distribute the information more widely.

“We’re looking at summer school because we don’t provide transportation to summer school students,” said Rick Gammill, the district’s director of transportation.

Rexroad said she’s helped several families plan how to use the T to get their children to school. She had no statistics indicating how may children use the system. The bus fare is 50 cents per ride.

“I think anybody who lives in an area that can easily access the bus system and needs to get to school, we’ll be happy to accommodate,” she said.

City Manager Mike Wildgen said the city might be willing to step up efforts to help students and their families learn to use the bus system.

“We’re looking for any way to encourage ridership,” he said. “If the school district’s a source of riders because of some of the decisions they make, then we’re ready to do some training and help out that way.”