Never seen one of these things before
October 25, 2015 12:24 AM   Subscribe

What's this thing embedded in the asphalt on the street? [Link] (They are in various places on the street)
posted by Dansaman to Technology (8 answers total)
Looks like some sort of survey marker to me.
posted by _DB_ at 12:35 AM on October 25, 2015 [2 favorites]

How big is it? If its' the size of a largish coin, I'd say a survey or utility marker, though utility markers are usually less cryptic.

Not sure why the strange notched bit is in there; it makes me think that the marker is made to mate with something else, maybe with a magnetic attachment that fits those notches so it isn't rotated by the casual passerby. We've got some disks in our sidewalks here that're, oh, smaller than a CD, but nearly that size, which mate magnetically with no-parking signs that can be changed as needed. (It's frequently a loading area for events at a nearby park).
posted by Sunburnt at 12:41 AM on October 25, 2015 [2 favorites]

Are you in California? Searching for LS-5411 turns up stuff like this, might be a survey mark put there by this specific guy.

The central part does look weird though, if it's in a spot on the road where it's getting run over by cars it can't be good for tires.
posted by Dr Dracator at 1:09 AM on October 25, 2015 [1 favorite]

The aluminum disk is a survey marker - the numbers would indicate the plotting point. The steel beveled gear is the top of the pin driven in to hold the disk in place. The pin is actually a recycled cotton gin spindle. The pointed end has sharp notches. In a cotton gin the pins rotate and separate the cotton fibers from the boll. After so many hours of use, they wear and are changed. Most cotton farmers replace hundreds every year. Since they are a chromed, hardened steel pin, and several inches long, they make terrific stakes to hold down survey markers. Since they are magnetic, they can be located even when covered over.

They are not particularly healthy on tires as Dr Dractor noted above. In fact, I pulled one out of a (flat) truck tire a month or so ago. But the one I found was probably lying loose on the road when the tire picked up the pointy end!
posted by tronec at 1:21 AM on October 25, 2015 [24 favorites]

The "LS" means Land Survey and the 5411 is the registration number for the surveyor, as the doctor has noted. Its location is undoubtedly a corner of a lot or parcel. I'm thinking that this one screws into the asphalt and that the ridges provide purchase for the device that screws it in. I would bet that the ridges are recessed so that tires pass harmlessly over it.
posted by megatherium at 6:33 AM on October 25, 2015 [1 favorite]

Response by poster: Yes I'm in California, and the locations I've seen these things in are in cul-de-sacs, sort of right in the middle (although maybe not exactly) of the round end of the cul-de-sac. So I still don't understand why these things have been seemingly permanently fastened to the street surface. Why do they need to be there permanently and what will they be used for on an ongoing basis? Or is someone going to come remove them at some point in time?
posted by Dansaman at 8:00 PM on October 25, 2015

They need to be there permanently so later surveyors can find them again when the need arises, maybe decades later.
posted by megatherium at 4:07 AM on October 26, 2015

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