In recent years, waves overtopping seawalls due to winds and tides have often caused traffic obstructions at certain locations on several highways running along coastlines, as well as have adversely affected daily life along the highway. Within areas under the jurisdiction of the Kinan Work Office, waves have overtopped seawalls at certain locations along National Highway No. 42, which passes along the coast of Kii Peninsula. Particularly in the Nishimukai area of Koza Town, Higashimuro County, Wakayama Prefecture, there have been traffic difficulties every year since 1994 due to waves overtopping seawalls and boulders washed up onto the road by typhoons or depressions. Then traffic control such as using a single lane or road closure is necessary. The Kinan Work Office has been studying a method and establishing a system for detecting and forecasting waves overtopping seawalls, to implement efficient road management with proper information of not only conditions but forecasts of wave overtopping seawalls, and to support safe driving by providing timely and proper information.
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