While there are several types of road closures a road race can use, remember that any road closure usually requires a permit from the local municipality with permission sometimes required from several authorities.
A full road closure is when neither vehicular traffic nor stationary vehicle parking, besides race vehicles, is allowed on course. All intersections must be closed to outside traffic. This is the safest approach though hard to get city or town permission because it is disruptive to the community and usually high in cost. Most municipalities require a traffic control person to close down roads or direct traffic. Criteriums, youth races for age six to nine, and cyclo-cross races must be on a closed course. A cyclo-cross race it is much easier to secure a closed course than a road race due to venues. If you have a full road closure make sure you alert the residents and businesses along the course. Letting them know when the roads will close and re-open goes a long way to show concern for the local community.
Another road closure option is a rolling enclosure- think of a presidential motorcade. A rolling enclosure is typically run by the local law enforcement officials who clear traffic from the road as the race approaches. The race vehicles keep traffic from passing the race and re-opens the road after the riders pass. The race usually uses the entire width of the road. If your course uses a rolling enclosure, a tentative schedule should be provided to the community to let people know when they might be delayed. This also lets them know when participants are expected to be rolling by, which can be a good way to get some spectators at the event. Use notice signs, newspaper, and radio announcements.
A partial road closure will also need a traffic control person at the intersection until the road is open. This could be a one lane closure on a four lane road, or perhaps a closure in one section of the race.
Road closures will increase your budget significantly because of the cost of police officers or certified traffic control personnel (flaggers) – depending on state laws. If you are lucky, your municipality may have a budget they use to cover special events, but other times you’ll be responsible to pay the police officers which sometimes be as much as time and a half. In some states a certified flagger can man an intersection and they are cheaper than a police officer so check with the local authority on what the state requires at an intersection.