Dix Drawbridge

[Downriviera]

Does anyone know why they have two hoses constantly spraying water on the surface of the Dix drawbridge over the Rouge? They don't do it on the Fort Street or Jefferson drawbridges. Just curious.

[RaumVogel]

Maybe they painted it with lead based paint.

[East Detroit]

To keep it from expanding too much and locking up.

[Meddle]

^^^ I was going to say pigeon dropping removal, but keeping it cool in high temperature weather makes sense.

[RaumVogel]

To keep it from expanding too much and locking up.

Ah....the heat.

[BillyBBrew]

Was down there a few years ago watching the Herbert C. Jackson come in on a very hot day. Bridge went up about 10 feet and pinched, even with the hoses on it. I knew the Captain on the Jackson, so I called him up to warn him the bridge was not opening so he'd be prepared. We discussed it and I suggested that they pull up as close to the bridge as possible and use the fire hose on the front of the forward cabin to spray it down. I spotted them so they wouldn't get too close and then they sprayed for about 20 minutes and the bridge went up! Water is one of the rare things that actually expands when it cools.

http://www.flickr.com/photos/theempi...er/4960169015/

[Downriviera]

Thanks, and great pic. Why don't they have the same problem with the Fort St and Jefferson draw bridges?

[ndavies]

Water is one of the rare things that actually expands when it cools.

That's not entirely true. Water is most dense at 4 degrees celsius, Just above freezing. It shrinks as it cools down to 4 degrees and then it starts to expand as it continues to lose heat. If this wasn't true, Summer lake water would be cooler on the top or winter ice would form at the bottom of the lake.

[mikeg19]

Someone enlighten me because I've never heard of this being done before. Is there a structural problem with the Dix bridge where this happens in extreme heat or is this a common problem for many drawbridges?

[BillyBBrew]

Thanks ND for that info. I definitely am not a scientist. From what I know, the bridge has had the binding issue since it was rebuilt back in the 1980's or early 90's. It also could be something as simple as a pier slightly settling or anything else. It doesn't take much when you have to things that close together. I think the original grated deck is now paved with concrete. [[or so it appears when you look at it)

[One Shot]

Water expanding has nothing to do with them spraying it on the bridge. What is probably happening is the metal is expanding in the hot sun and due to a tight tolerance somewhere is causing a bind. Spraying water on it cools the metal back to it's as-built dimensions allowing proper operation.
The other bridges may differ in design thus eliminating this issue.

[BillyBBrew]

One Shot,

I actually was adding to the thread repsonse posted by "East Detroit" stating it was probably due to metal expansion, which is the correct answer. Nothing whatsoever to do with water expanding, just was an afterthought.

BBB

[Downriviera]

BillyBBrew,

Had you not contacted your friend on the Jackson what would have happened? I'm guessing the bridge operator is in contact with the ships?

[BillyBBrew]

They would have stopped and waited. It was just a courtesy heads up so he'd know what to expect. When you're on the ship watching the bridges, you watch for the gates to go down. Then you expect the bridge to go up, especially if it starts going up, but you also learn to expect the unexpected and have a contingency plan for everything, even your contingency plans. Shiphandling is years of boredom mixed with random moments of sheer terror.

[1KielsonDrive]

Hey Billy, I'd sure like to get a copy of that photo.