I'm proposing on running a level loop though a 7000 foot long tunnel. They want eye bolts put into the walls at about 300 foot intervals that they can pull a string across and pull elevations off to set a pipe laser. I'll also need to station the eye bolt locations. They may be good with just markings and then place their own eye bolts.
I'm wondering about what are the best lights, headlamps, flashlights to use. Can anyone with this sort of experience make some recommendations. There is no power in the tunnel. The tunnel is 5 to 6 feet wide and 6 to 7 feet tall. It's a water tunnel that is going to be lined with a new plastic pipe and then grouted in, I did the design topo of the entrance and exit last year.
I need some good stuff, don't want to be 3500 feet from an entrance and in the dark.
If I were you I'd be much more concerned with other things. You can't take breathable air for granted when you are underground 3500 feet from the nearest daylight. That's the grandaddy of all confined spaces.
Why not RTK?
I'm not a big fan of safety requirements at times, but here's a good place to get a general idea:
Jim_H, post: 383536, member: 11536 wrote: Why not RTK?
That's a silly question! The answer, of course, is that it's too hard to plumb the bubble in the dark.
Mark Mayer, post: 383534, member: 424 wrote: If I were you I'd be much more concerned with other things. You can't take breathable air for granted when you are underground 3500 feet from the nearest daylight. That's the grandaddy of all confined spaces.
The contractor is responsible for cleaning out the tunnel and for the air supply. I'm not going in unless OK with the air. Plan on keeping in contact with someone out side at all times, radios probably but if that won't work the contractor will need to run some wires. We''ll just comply with what the contractor needs to. The tunnel is straight and has the original rails in it which they are going to rehabilitate and use.
The tunnel seems to draft naturally and I've heard of many people hiking through it.
Back in the day I was low-man on a crew that chained through an active railroad tunnel as part of a fiberoptic design survey. No coordination with the railroad, no signs, so safety training, just "Here's your route, let us know now long it is." I get the willies just thinking about the stretch through that tunnel. It was less than 1,000 feet long (probably much less), but the entire time we were in it I was wondering how well I could stick myself to that tunnel wall if the dreaded headlight appeared.
Leon,
My underground survey work was for hard-rock mines so may not be wholly applicable. The mining company supplied the personal protection gear (hard hat, lamp, self-rescue device, steel toed rubber boots and waterproof bibs and jacket). I never had any problem with the miners lamp going out. I wasn't running differential levels. For the traverse work, I used Wild illuminated targets for the foresight and backsight. They worked very well, esp. in areas with short backsights (as short as 25 feet). That shouldn't be a problem for you. Are you going to run trig levels or differential levels?
You may run into problems with refraction. Many years ago John Hamilton posted about his underground control survey work in the Andean mountains. Hopefully he will chime in with suggestions and methods to reduce its effects.
Now for the safety issues. Are you required to have health and safety training for the project? Being that far underground, fire is a real safety issue. In hard-rock mines, the self-rescue device absorbs carbon monoxide, but it doesn't produce oxygen. For coal mines the self rescue device will provide up to an hour of oxygenated air. Be safe!
I am pretty sure you can get a liiuminated level rod from Nedo.
Mark Mayer, post: 383534, member: 424 wrote: If I were you I'd be much more concerned with other things. You can't take breathable air for granted when you are underground 3500 feet from the nearest daylight. That's the grandaddy of all confined spaces.
Good advice from Mark. Nothing more fun than passing out from lack of O2 and an abundance of CO2.
You might want to check this out: http://www.rkiinstruments.com/pages/gx2009.htm
We run levels in water tunnels several times a year, using a digital level. Also in a dry air gallery tunnel. After trying various methods of lighting the rod, the best way I have found is using LED lights, we bought a 30" battery powered strip of LED's. Works great. We also use a shorter "work light" version, similar to this:
As for horizontal, you need to be careful about refraction from the walls. Best way to do that would be to alternate sides.
Theoretically the orthometric/dynamic correction formulas would need to be modified to take into account the possible thousand(s) of feet of rock above you as you get to the middle of the tunnel. If there isn't a lot of elevation change in the tunnel, then ignoring the correction would keep you pretty close to dynamic heights, which is great for water flow work. Perhaps John H. can tell us whether this is worth thinking about.
LRDay, post: 383543, member: 571 wrote: The contractor is responsible for cleaning out the tunnel and for the air supply. I'm not going in unless OK with the air. Plan on keeping in contact with someone out side at all times, radios probably but if that won't work the contractor will need to run some wires. We''ll just comply with what the contractor needs to. The tunnel is straight and has the original rails in it which they are going to rehabilitate and use.
The tunnel seems to draft naturally and I've heard of many people hiking through it.
I would keep an electronic canary on me at all times (O2 sensor/gas sensor).
Gene Kooper, post: 383549, member: 9850 wrote: Leon,
My underground survey work was for hard-rock mines so may not be wholly applicable. The mining company supplied the personal protection gear (hard hat, lamp, self-rescue device, steel toed rubber boots and waterproof bibs and jacket). I never had any problem with the miners lamp going out. I wasn't running differential levels. For the traverse work, I used Wild illuminated targets for the foresight and backsight. They worked very well, esp. in areas with short backsights (as short as 25 feet). That shouldn't be a problem for you. Are you going to run trig levels or differential levels?
You may run into problems with refraction. Many years ago John Hamilton posted about his underground control survey work in the Andean mountains. Hopefully he will chime in with suggestions and methods to reduce its effects.
Now for the safety issues. Are you required to have health and safety training for the project? Being that far underground, fire is a real safety issue. In hard-rock mines, the self-rescue device absorbs carbon monoxide, but it doesn't produce oxygen. For coal mines the self rescue device will provide up to an hour of oxygenated air. Be safe!
Plan to use my Zeiss DiNi 10 digital level. I've used it a bit in the dark before, just need to illuminate the rod just right. It's a tunnel for open channel water flow so as long as the level reads gravity as water does can't get to far off.
The contractor is well experienced in tunnel work, so what ever training we need we'll get.
Initial plan is to get a 1/2 meter rod and set on a tripod with tribrach. If we can get 150 foot shots then will mark the walls at the instrument HI at each set up. We will modify from there to what ever works. The tunnel is on a 3 tenths grade, so about 1 foot drop every setup (300 feet). Maybe a meter rod would work better on a short tripod.
When I was working in Peru, I was only checking the alignment (direction) right before they were to meet in the middle.
But I would say the correction would be so small over that distance as to be negligible.
We have a dini 1 meter rod, what is nice about that is it is also graduated to mm on the side.
LRDay, post: 383603, member: 571 wrote: Plan to use my Zeiss DiNi 10 digital level.....
...The tunnel is on a 3 tenths grade, so about 1 foot drop every setup (300 feet). Maybe a meter rod would work better on a short tripod.
What does the project scope cite for tolerance? I rather doubt they will re-mine the tunnel if it is not at the design grade.
When we have had to work in the dark, we use LED lanterns that have the green strips that give off light for general work tasks and not cheap LED flashlights with a good beam for sighting work. We buy these from our interstate battery dealer, but any good public safety supplier should also have these same kind of lights, and both places should be happy to find you a dark place and show you how well the lights work. Cheap will not work!
Mike Falk, post: 384917, member: 442 wrote: What does the project scope cite for tolerance? I rather doubt they will re-mine the tunnel if it is not at the design grade.
The grade was estimated from the inlet and outlet. A precise level loop has not been run. I'm sure the grade will be tweaked to fit the existing tunnel and rails. They want points at about a 1/4 inch tolerance set in the walls at 300 foot intervals or so. I shouldn't be that hard to achieve unless being underground upsets the DiNi for some reason.
Got an email today that they will issue a contract next week.
The contractor will be putting in the ventilation and mine phones beginning next week.
Get us pictures or it didn't happen!
James
One thing you didn't mention: Is the Tunnel on tangent or curved?
