Cable Dampers

“When you want to know how things really work, study them when they’re coming apart.”
― William Gibson, Zero History

Cable anchor and damper on the Margaret McDermott Bridge, Dallas, Texas

One reason I was so excited about the final opening of the bike/pedestrian lanes on the Margaret McDermott Bridge is the long, sad, awful story of its construction.

To make a long story short, to save a little money, the city skipped some engineering testing on some elements of the bridge – which had been greatly modified to save money already. Once the thing was finished, several cable anchors cracked in the high winds that are common in Texas. There was an orgy of blame and recrimination and I really thought that the bike part of the bridge would never open.

Finally, the city decided to pony up seven million dollars or so for repairs and try to claw that money back later.

So when I crossed that bridge for the first time I took a look at the cable anchors to see what was done. There wasn’t much that was all that obvious.

Here’s a photo of the original cable anchors:

Image from Dallas Morning News

So it looks like the rod connecting the cable to the bridge is a bit thicker. The big difference seems to be the addition of cable dampers – which are (I guess) the funny looking barbell-looking things mounted to the cables right above the anchors.

They look kind of cool – but it’s hard to believe that these little things are keeping a two hundred million dollar bridge from falling down.