As a solo surveyor, when I need tight elevations I run a differential level loop using a standard level and a rectangular rod that works with a special thumb-release bipod made for a rectangular level rod. This works okay but not great since the rod can fall over easily from only a slight breeze.
I am about to purchase some new equipment and as far as I know there is still nothing out there that makes this any easier than the standard level/level rod set up. But just in case, I thought I'd ask around before making my next purchase.
I think I will try a thumb-release tripod instead a bipod. The tripods I have found will only work with a round rod and with a max dia of 1.5". The smallest dia round level rod I have found is 1-5/8". I figure a fabricator can fix the tripod so that it will accept a larger rod.
Jim,
I use a laser level. Set it up, go to backsight, adjust the "eye", read rod.
Walk to foresight, adjust the "eye", read rod.
Walk back to level.
Move ahead.
Repeat.
Yes, there IS a lot more walking. But I can do it alone very easily, and I only have to depend on myself.
My 2 cents
Geezer
> As a solo surveyor
I thought you worked for a big firm. Can't you drag an office monkey out when you need to run levels?
I once ran a 1/2 mile loop (1 mile total) by myself with a level and rod. I took a standard aluminum tripod, removed the center screw and bored out the hole to accept a regular Sokkia rectangular fiberglass rod. I used a rubber band to hold a rod level on the rod. I was a pretty simple matter to slip the legs around to plumb the rod. The biggest trick was to make sure that the tripod head didn't block the shot.
However, I can't recommend the procedure for efficiency. You have to walk 3 times as far as you would with a 2-man crew, and you have to leave the instrument unattended while moving the rod ahead.
I believe I can get results that are as good or better by running trig levels with a robot, and I can get much longer shots, especially in steep country. I still have to leave the instrument unattended, which can be a big problem in some areas.
I dont know why Ive never considered a lazer level. I think it would actually be less footwork than a diff level.
Thanks G
trig levels...You can use one or two prism poles with bipods. Keep sights short (under 100 meters or so) and you can easily match a level in accuracy and much faster, you don't have to worry about hills (i.e. sights are not horizontal).
Topcon Laser Level here for short stuff, or set up my Geodimeter robot. Or enlist the wife to help run loops.
I try to get trig levels to work with my 5" robot. But results are usually a little too loose when the elevations need to be especially tight.
Anyone else out there happy using a laser level?
I use a laser leveling grading at times and for the occasional short level runs during construction projects where the contractors destroy benchmarks like it's going out of style. For everything else I trig it with the robot.
Topcon laser here. Just like any level, close your loop so you got checks, and balanced shots, I have noticed some discrepancies when I start stretching out the distance.
For Solo, Trig-Leveling is the way to go, but you have to know how to do it right. For instance, in true Trig-leveling, you never measure the HI of your instrument and it is important to have 2 rods that are completely identical in height. If done correctly you can achieve 3rd order precision without too much trouble. I have found that the maximum sight distance is about 500-600 feet. Oh, and I sight them in myself. I don't trust the robots sighting that much for Trig-Levels.
When my wife sold her house in Texas, when we got married, the Real Estate Agent suggested that she have a structural engineer do a foundation inspection on the house. They have a problem with foundation damage in the DFW area. The house was built on a slab, and he used a water level to check the floor elevations for vatiation. I watched him do it, and it was pretty simple to operate. He said that it was accurate to less than 0.01 feet. They were an established firm, had been in bussiness for several years, and had $1 Million of E&O coverage, so I took his wowrd for it. With a long hose, you could get there in 1 shot.
I know you are being facitious but it made me wonder. Would it work over uneven terrain? If you had a high spot near the beginning wouldn't all the water weight in the hose skew the results?
They better keep the $1M E/O.
Andy J: What have you found the max distances you can stretch your laser level shots?
Bow Tie: Would you share how to achieve 3rd order levels with a TS? I obviously haven't figured it out. I suspect the HI measurements account for most of the error when using a TS for precise levels. The best way Ive figured to not actually measure Hi's was to take the initial BS with a HT of zero, and let the BS error effectively indicate the true HI (with the same rod with same height used for the BS/FS). That seemed to work but in the long run some errors came to light. I would be most interested to know how this is done.
You run it just like you would levels. You set the gun up at a random spot (not over a point), backsight to a prism on a pole, then move the pole ahead and foresight. THE SIGHTS DO NOT HAVE TO BE BALANCED if you do at least 1 set of D & R. Horizontal angles are discarded, you only need to record distance and vertical angle or the Delta Elev displayed on the DC can be used instead (preferable). You need to be aware if the displayed values are being corrected for C+R. You don't want to apply that twice or not at all.
Actually water level measurements can be very accurate even over long distances. If you place water in a hose, it will rise to the same level at both ends.
Even if one end is six feet above the ground and the other is sixty and the hose lays along the 15% slope of the ground? My logic says the weight of the water in the hose would have to put more pressure on the sixty end. There has to be some hydraulic calculation involved.
If Im not going to get the benefit of my x,y positions along with z while using a TS, Im not so sure it would be faster/easier than diff levels. Granted, a site with lots of relief might be a another story.
> Even if one end is six feet above the ground and the other is sixty and the hose lays along the 15% slope of the ground?
In that case the water will run out of the hose at the 6' end until the pressure equalizes. That's what we mean when we say "level."
Not sure I would trust an office-monkey. In my opinion, levelling is such a simple concept, and so boring to most, that more people make mistakes because it almost required too little attention. A lot of engineering techs in big companies would probably start out thinking that work is beneath them as well and be there begrudgingly.
But if you did have good office help that might go out, I think it is almost better to do it with three guys than with two. In my head it is nearly twice as fast as with two. Your read the backsight, call off the back rodman, and then read the foresight (no waiting for the rodman to move forward and find a spot). You walk forward, and read the backsight, and the guy that started walking before you has moved up and is ready for the fore-shot. Nearly constant moving, and not moving and waiting, moving and waiting.
As to (and back to) the original thread, I think I would be pursuing trig-levels if I were doing 1-man runs. I've never done it, so I might be wrong on the most efficient way.
TRIG LEVELS/TS Jesse Kozlowski,PLS
Others have written articles by this one shows...
http://www.fgg.uni-lj.si/~/mkuhar/Zalozba/tv/Trig_Leveling.pdf
