Washed out roads in rural areas have the possibility of disrupting daily life for weeks, and sometimes for months.
One of the problems facing rural counties is the amount of tax money allocated to them for road maintenance and upgrades. Believe it or not, there are thousands of miles of dirt roads all over the United States. Rather than putting in bridges over creeks, culverts are used.
Well, culverts only allow X amount of water to pass through them. When the flow of water exceeds X, the water starts to back up. Eventually, the water will find a way around the culvert. This typically means the water goes over the road, which causes erosion.
With enough time, the flowing water erodes the road away.