Every coastal state has highways that run along and to the coast and are exposed to the unique design forces during storms. The Center has been working toward an estimate of the length of these "coastal highways." We have used GIS techniques to measure the length of roads that are inundated by FEMA's estimated 100-year storm surges. Counties in 26 of the 30 states located along the coast of the US are included in the estimate. This includes states on the Atlantic , Pacific, Gulf of Mexico , and Great Lakes coasts. The results have been adjusted for coastal storm surge flooding (not rainfall runoff flooding).
The result is that over 60,000 roadmiles in the US can be considered "coastal highways." Within any one state, coastal highways may not be a significant percentage of the total highway miles, but they are often some of the most economically critical miles and may suffer disproportionate damage in storms. These are also miles of roads that are passing through unique coastal ecosystems.
Nationwide, these 60,000 miles of coastal highways are going to become more and more important in the future. Census trends indicate that coastal population densities and coastal economic activities will continue to increase at disproportionate rates. It is also established scientific fact that sea levels are rising and storminess is increasing. Thus, there will be both increased natural and increased societal pressures on coastal highways in the future. How we respond to these pressures will effect the lives of millions of Americans.