More than 2,500 athletes are competing Sunday in the ninth annual Ironman Triathlon.
The 2.4-mile swim, 112K bike race and 26.2 mile marathon impacts roads in Madison, Fitchburg, Verona, Mount Horeb and much of western Dane County.
During much of the triathlon, Dane County sheriff's deputies, local police officers and volunteers will direct traffic at all major intersections along the course.
Authorities are asking drivers to use caution when approaching these intersections and to follow the traffic directions given by law enforcement to ensure safety for drivers, Ironman participants and spectators.
Dane County sheriff's officials said the triathlon could cause traffic delays Sunday.
For more information about the Ironman Triathlon courses, people can visit the Ironman Wisconsin website at http://www.ironmanwisconsin.com/.