Several streets in and around downtown will be closed for the Ironman Triathlon on Sunday, September 10th.   The race consists of swimming in Lake Monona, bicycling in Dane County, and running in the downtown/campus area.  The race starts at 6:40 a.m.  City of Madison road closures for the bicycling portion last from about 7:30 a.m. until about 5:30 p.m.  Road closures for the run portion last from 11:00 a.m. until about midnight. 

Course maps:
http://www.ironman.com/triathlon/events/americas/ironman/wisconsin/athletes/course.aspx#axzz3lA7ZxrM2

Downtown traffic map:
https://www.cityofmadison.com/trafficEngineering/documents/IronmanTrafficRoutes.pdf

Metro Transit detours:
http://www.cityofmadison.com/metro/detours/ironman/index.cfm

If you have any questions, direct them to the contact person listed above.