Magnesium chloride at interstate bridges

[n5usr]

Okay, not a radio question at all, but this seems the likeliest place to get an answer! I know a few here might know...

I've been driving to Weatherford and back quite a bit lately, and started wondering again about the big poly tanks I see at one end of some of the bridges on I-40. Finally saw the sign on one today, "magnesium chloride" which can be used as an anti-icer.

So, is it just there to make it convenient for a truck to use? Or have they actually plumbed the bridges so they can disperse the stuff automatically?

Reading Wikipedia on it, sounds like it has to be applied *before* icing occurs, so would perhaps make sense if it's actually plumbed in...

[N2JDS]

In Missouri, they use that a lot, Nice thing about it is they can pre-treat up to a few days before the expected storm. Even if it gets rained on, it is still efective somewhat. They use a simple (approx). 2" pvc pipe with holes in it about 4" apart the width of the truck, and it simply drains/drips at low pressure. It at first was just used on bridge decks, then they (in my area) are using it anyplace they want, even on side streets. I'm not sure it's the exact same formula you saw. I think I saw at a state shed they simply mixed road salt into a vat with some water, and letting the salt disolve. May have been an experiment though to see if it would be a cheap way to do it.

[n5usr]

I'll have to take another look as I drive past today. I can't remember for sure, might be confusing the tanks with something else, but I think I remember seeing a solar panel alongside at least one tank so they may well have plumbed the bridge. (Hard to tell much as you whiz past at 70 MPH...)

They aren't at every bridge, only a handful that are particularly long or sloped.

I've seen them there for a while, and always wondered what they were for. Just usually forgot all about them by the time I got back home! Idle curiosity...

[GTO_04]

You can buy magnesium chloride, in pellet form, at Home Depot to use on your own driveway. It spreads just like salt. It works down to lower temperatures too. The question is how corrosive is it? Doesn't seem to be to hard on the concrete driveway though.

GTO_04

[plaws]

Originally Posted by GTO_04

You can buy magnesium chloride, in pellet form, at Home Depot to use on your own driveway. It spreads just like salt. It works down to lower temperatures too. The question is how corrosive is it? Doesn't seem to be to hard on the concrete driveway though.

GTO_04

One of the others is ... potassium chloride? Bought some under, I think, the Prestone brand back in the 1990s when we were in a rental townhouse. Winter Heat or something. Threw some out on the back deck and it sure melted the ice.

.... And then went to work on the top layer of concrete! Spalled it all off. Dunno what would happen if you just piled it on. Down to the gravel underneath?

Hope ODOT can keep their KCl, CaCl, NaCl, and MgCL straight!!

[Thayne]

Another downside to mag chloride is that after awhile being used around areas that have a lot of primary power lines it tends to collect on insulators and causes arc tracking when it gets wet and causes pole fires & thus power outages. The power companies and road & bridge guys are always debating about it.

[N5TWB]

N5USR -

Since you have spotted the tanks, you should also be able to see the plumbing and spray nozzles that are associated with the system on the bridges. They generally run along the top edge of the concrete rails. I have seen the system in operation during near-freezing weather and the bridge deck was not frozen.

[tkjr4160]

I just noticed this today on the I-44 bridge over US412 heading onto the Will Rogers Turnpike. That is funny because I was like I wonder what that is? I log on here and obviously I am not the only one.

[n5usr]

I haven't seen anything I immediately recognize as plumbing on the brides themselves, that's what I was most curious about. There *is* a black tube or cable running down the *outside* of the inner bride railing (there's a gap between east and westbound lanes) but it's in a poor position to spread anything on the bridge deck, since the railing is solid. It's just hard to see much at 70 MPH! Not too inclined to stop for a closer look!

However, the tank does also have a Yagi antenna and weather station alongside, so makes sense they've plumbed the bridge. This was at the bridge crossing the Canadian River just east of Methodist Road, it has the largest tank by far - of course it's a much longer bridge too.

Hm, I don't remember which direction the beam was pointed. I want to say east, but will have to pay more attention to that this morning. Would DOT use the state system for something like this? In that case, I'd expect it would point toward the Geary site, which is still west-ish. (Hey, I worked radio into this at last! )

[Confuzzled]

If there's a Yagi and a weather station, it's operated and monitored by ODOT. Kentucky does that in some places and posts the information to a website where anyone can read the data.

http://rwis.kytc.ky.gov/

[n5usr]

Well, I did say I have a terrible memory, didn't I? The beam was on a different bridge, I couldn't see any obvious antenna at the Canadian River bridge but there was an arm off the side of the weather station that may have held a small one.

And I *did* finally see some of the dispersion tubes, the black tube on the backside of the bridge wall is from the tank, and they drilled through the wall at a few points and passed through some white tubing. If I keep having to go to Weatherford, I might just see it in operation soon... (Hopefully not.)

I've done the slip-n-slide on bridges before, that gets scary. Having something to help prevent it will sure be nice!

[n5usr]

Originally Posted by Confuzzled

If there's a Yagi and a weather station, it's operated and monitored by ODOT. Kentucky does that in some places and posts the information to a website where anyone can read the data.

Kentucky Roadway Weather Information System

Now those are cool. All kinds of nifty data from their systems!