Cable Helps Lift Bridge 20 Times a Day
The Stillwater Bridge is raised and lowered at least 20 times a day during navigation season and the cable that controls it is unwound and rewound as many times.
After large rubber insulated cables for this lift bridge connecting Minnesota and Wisconsin failed in less than two years, a reliable signal cable to control the bridge’s vertical lift span was needed.
"We originally employed another manufacturer's electrical control cable in the refurbishing project, but it failed within six months due to incorrect design, causing the lift span not to function and necessitating a temporary and costly ad hoc remedy", says Bob Quist, Project Manager, AA Hanson Electric in Osceola, Wisconsin.
"We looked to Northwire – a hometown company – to design a new control cable".
"Northwire visited the site, designed a solution, provided the design to the Minnesota Department of Transportation, got approval and produced the cable - all within three weeks", says Quist.
"We were very pleased with Northwire's turnaround and the smaller-diameter cable is more flexible and winds more easily than the originally specified bigger cable".
The Northwire cable is one-third smaller than the previous cable and the insulation is comprised of Hytrel from DuPont, which provides its high-flex life properties.
Anywhere from 10,000 to 20,000 cars pass over the bridge each day. From mid-May through mid-October, the bridge's lift operates on a regular schedule when boat traffic is present. Outside of the regular lifting season, the bridge is raised on request.
