A bypass is a road or highway that avoids or "bypasses" a built-up area, town, or village, to let through traffic flow without interference from local traffic, to reduce congestion in the built-up area, to improve road safety and as replacement for obsolete roads that are no longer in use as a result of devastating natural disasters (earthquakes, tsunamis, landslides, volcanic eruptions). A bypass specifically designated for trucks may be called a truck route.
If there are no strong land use controls, buildings are often built in town along a bypass, converting it into an ordinary town road, and the bypass may eventually become as congested as the local streets it was intended to avoid. Many businesses are often built there for ease of access, while homes are often avoided for noise and pollution reasons.