Salt Pollution of the Overhead Contact Line Insulators at Honsyu-Sikoku Bridge
Kohji AJIKI, Yoshifumi MOCHINAGA
Seto Ohashi Bridge comprises a four-lane highway and double-track railway, as
well as two tracks for a Shinkansen line to be constructed in the future. This
bridge combining highway and railway spans has an upper deck devoted to highway
and a lower deck devoted to railway. Salt pollution of the lower deck was
investigated. The main results are summarized as follows.
The wind blows east-west or west-east throughout the year, unlike in the seaside
districts of Seto Inland Sea. The maximum instantaneous wind velocity at the
bridge is 55.5m/s caused by typhoon, and it is confirmed that the velocity for
the local altitude is by far higher than in other seaside distrits. The insulator
surfaces suffer heavy in salt pollution typhoon season and in winter dry season.
The maximum salt deposit record of 250mm suspension insulator surface is 0.13mg/cm^2.
It is concluded that the severity of pollution on Honshu-Shikoku bridge is rated
medium degree according to the classification by Society of Electrical Co-operative
Research.