Presidential visits can be exciting, but they also present many logistical headaches, upending a city's normal routines.

Such can be expected on Tuesday, when President Obama flies into town for a speech at the UW-Madison library mall: flights will be canceled, traffic and buses rerouted, and areas of campus normally public will suddenly have the highest security.

"Generally there's very serious security -- the airport, the route, and the library mall," says Joel DeSpain, Madison police spokesman. "It's a multi-jurisdictional call up, including us, Dane County Sheriff, Wisconsin State Patrol, and UW Police."

"Our role is really facilitating the motorcade, airport. Venue security is partially ours, but it's a lot of agencies involved," he says. "As that motorcade rolls through, intersections are blocked. It's all very temporary. The area where he speaks, is really heightened security. People really can't get into that area after he's there."

If you want to attend, the event is free. No tickets are required, but organizers request a press release, there's only one-way into the mall area: Park Street at the base of Bascom Hill. The gate opens at 3:30 p.m. Everyone will be screened by a metal detector. Many items are forbidden, including laptop computers, sharp objects, metal or plastic drink bottles, backpacks and bags or purses larger than a standard sheet of paper, posters, and any food or drink.

Some city streets will be closed for the event: Langdon Street will be closed between Park Street and Lake Street, and Lake will be closed north of the Lake Street Parking Ramp. Park will be closed from Lake Mendota to University Avenue. Observatory Drive remains closed due to construction. And motorists should expect delays on streets that remain open.

Several Madison Metro buses will be detoured for most of the day, including routes 4, 6, 29, 80, 81, 82, and 85. See a map for specific routes. Pedestrians and bicyclists are also expected to be detoured around the site.

People with mobility disabilities can park in Lot 3 and enter Library Mall via North Lake Street and Langdon until 5 p.m.

The event is expected to last several hours.