Why does Mn/DOT build noise walls?
A. In 1976, the U.S. Congress passed legislation requiring the states to provide mitigation for highway noise (considered an environmental impact) as a part of all Type I Federal Aid projects at impacted locations where it was found to be reasonable and feasible. Mn/DOT also builds noise walls for Type II projects, which are ranked in priority by the Minnesota Highway Noise Priority Study, directed by the Minnesota Legislature.