Salt Pollution on the Overhead Contact Line Insulators at Honshu-Shikoku Bridge

Abstract

Seto Ohashi Bridge comprises a four-lane highway and double-track railway, as well as an additional two tracks for a Shinkansen line to be incorporated in the future. This series of highway-railway combined spans has an upper deck for the highway and a lower deck for the railway. Salt pollution problems were investigated at this lower deck. The main results are summerlized as follows. The wind direction was East-West or West-East all through year, which was different from the seaside districts of Seto Inland Sea. The maximum instantaneous wind speed at the bridge was 55.5m/s caused by typhoon, and it was confirmed that the wind speed of this height was more rapid by far than the seaside districs. The salt pollutions on the insulator surfaces were heavy in case of typhoon and in winter dry season. The maximum salt deposit density of 250mm suspension insulator surface was 0.13mg/cm². It was concluded that the site severity of Honshu-Shikoku bridge is equivalent to the average pollution according to the classification by Society of Electrical Co-operative Research.