Dehumidification Breathes New Life into Suspension Cables on The Delaware Memorial Bridges

摘要

The Delaware Memorial Bridge comprises of two parallel suspension bridges thatspan the Delaware River between Delaware and New Jersey. The bridges are owned andoperated by The Delaware River & Bay Authority.Following an internal inspection of main cables in 2012, the Authority decided to installdehumidification systems on the cables of both bridges to address the corrosion occurring inthe high-strength steel cable wires. This was a significant resolution by The Authority as therewere no other suspension bridges in the United States where this technique of cablepreservation had been installed and operational at the time.The project is significant because it has advanced the industry’s knowledge of designing andconstructing cable dehumidification projects, which are a complex blend of structural,mechanical, electrical and control systems engineering.Cable dehumidification involves the injection of dry air into the cable body to remove water,moisture and to sustain relative humidity levels below a critical threshold where corrosionpractically ceases. To date, only two bridges in the US have had cable dehumidificationinstalled; however dehumidification projects on approximately six other bridges are currentlyin varying stages of development.This project, which started in early 2016, is anticipated to reach substantial completionapproximately three months ahead of schedule. This paper will present the project workincluding best practices to guide bridge owners who are considering the installation of cabledehumidification systems.