41?ø41'8.08"N
69?ø57'46.40"W
A few years ago, I set a DH in the middle of the concrete slab over a utility vault hanging out in the side of a hill overlooking the ballfield.?ÿ We have run some static on it over the years without issue.
Yesterday afternoon the crew setup a total station and it would not hold an angle.?ÿ They would zero out and the station would move about 4 minutes.
This morning they went out with the backup total station and had the same issue.?ÿ They setup on the sidewalk about 20' away and had no issue.
There used to be a siren nearby.?ÿ When I was a kid it would go off at noon everyday.?ÿ I do not recall when they took it down, but perhaps they placed it in the vault.?ÿ I don't even know if the thing had a big magnet in it.
I have a call in to the Town Staff to get into the vault to see what the deal is.?ÿ It is a great point for GPS and Total Station.
Does 'utility vault' mean lots of electrical power, perhaps a monster transformer? I can see that putting out electric and magnetic fields that could affect some equipment in close proximity.
Did you try a brass transit??ÿ See if its compass buzzes.
Or maybe you're just at a weak spot in the space-time fabric.?ÿ No telling when or where you will find yourself if it gives way. 😉
Backsight on 00-04-00
Problem solved.
Are you walking around on the vault? Maybe, if the lid isn't sitting on the structure right, it might wobble a little.?ÿ
It's probably somewhere in your set up...
The vault contains the 2" service and water meter for the irrigation of the ball field.?ÿ The top appears to be stable.?ÿ The electrical for the field is off 3rd base (2 large above ground electrical boxes), this is off centerfield.?ÿ?ÿ
- After the storm I will have to try out the old brass compass that we have never use for anything more than decoration.
That vault lid is flexing a little when you stand on it to set up your instrument.?ÿ Either that or your tribrach is worn out and unstable.?ÿ
Try setting up a robot on it, and see if that helps...
No one walking around, near it, while it spins the angles.
Is the concrete top integral with the sides, or is it a separate piece??ÿ If separate, there may be some ice in the joint, causing it to rock a bit when the weight distribution on top changes.
