Durability is a moving target.?ÿ Sometimes a nice copper disk set into a sidewalk gets torn out within weeks of it being set, and other times the cheesiest quick-and-dirty control point lasts for decades.
Today I did a survey of a lot in a block that I retraced in 2006.?ÿ One of my control points from the old survey was a concrete nail that I set partway into the street because parking in that neighborhood is so congested that you can't see anything from the sidewalks.?ÿ I found that nail today, looking just as good as it did in 2006, and it checked within a hundredth or two to 3 of the monuments from that time.
There's another concrete nail control point that I set in the pavement downtown near the railroad in 1994.?ÿ I've used it at least a dozen times in the intervening years, most recently last year.?ÿ It's like an old friend, but every time I see it I'm amazed that it's still there and still checks nicely to other control.
Maybe durability *isn't* a moving target, maybe there's a pattern that I've overlooked:?ÿ an inverse relationship between how long you expect a point to last and its actual longevity.?ÿ Hmmm...
There??s also the factor of how essential it is the project you are currently working on.... Murphy says if it??s crucial, you??ll watch them mill it out as you??re walking up to occupy it....
That's pretty cool Jim.
Finding old control that still works when unexpected is a bonus.
We were setting DOI BOR monuments on the LEP and REP of the Rio Grande and while out in the sticks these things seemed to last forever.
Closer to town, we were setting and the homeless people were just ripping them off or out and off went those tax dollars into a recycling foundry somewhere.
Credit due, those big flying saucer shaped 3.5in caps must have weighed about the equivalent to about 25 to 30 aluminum cans.....
I arrived at a bench mark I had previously seen, to do a GPSonBM session, and found fresh equipment tracks next to the broken off post. It was the only found GPS-able mark in about a county area.
Another time I sat in the car and watched a jackhammer on a crane take out an old abutment with the most stable high order?ÿ bench mark for miles around. I knew it was going to happen and went to watch. I saw a survey crew on that project and asked if they had done a reset and they looked at me like I was speaking Martian.
I had a property survey that was in a downtown section of town. I rented a core drill and drilled in 3" caps in concrete at the corners and added 3" caps at the controlling block corners. I was real proud of those permanent monuments. Well the property was sold, a gas station was built, site regraded, concrete sidewalks re built and of course all the monuments were removed. Then the state DOT did a reconstruction project and wiped out the block corners. All gone within a couple of years. Nothing is permanent.?ÿ
When I was starting out that kinda thing bothered me, now I figure any possible liability vanishes with the monuments.?ÿ
Too late as construction work had started in the area before I heard of it, I don't think my leveling equipment meets NGS requirements, and i couldn't have attempted that much elevation change without recruiting help.
Moving an NGS monument to their standards would be a big job these days. I did a few of them years ago, but the most recent proposal to shift one was rejected by the client that was taking out the old one as too expensive. We ended up setting a new monument, leveling to it and OPUS ing the coordinates but not to the standards required by NGS guidelines to allow it to be included in the database.?ÿ
When we added the meetings, the reports, the submittals ect to the cost, the client said no thanks.
?ÿ
Name That Tune:?ÿ Don't it always seem to go
That you don't know what you got 'til it's gone??
Durability is a moving target.?ÿ Sometimes a nice copper disk set into a sidewalk gets torn out within weeks of it being set, and other times the cheesiest quick-and-dirty control point lasts for decades.
Today I did a survey of a lot in a block that I retraced in 2006.?ÿ One of my control points from the old survey was a concrete nail that I set partway into the street because parking in that neighborhood is so congested that you can't see anything from the sidewalks.?ÿ I found that nail today, looking just as good as it did in 2006, and it checked within a hundredth or two to 3 of the monuments from that time.
There's another concrete nail control point that I set in the pavement downtown near the railroad in 1994.?ÿ I've used it at least a dozen times in the intervening years, most recently last year.?ÿ It's like an old friend, but every time I see it I'm amazed that it's still there and still checks nicely to other control.
Maybe durability *isn't* a moving target, maybe there's a pattern that I've overlooked:?ÿ an inverse relationship between how long you expect a point to last and its actual longevity.?ÿ Hmmm...
If those were property corner monuments, they would had been destroyed by now.?ÿ You're lucky
It's like an old friend
Yes
If you're ever lost in the woods, drive a hub and someone will come drive over it????
