How many feet per hour for surveying?

[Rick Brinkman]

I KNOW this is a loaded question, but ....


On another thread, questions of efficiency and survey crew size were brought up. I thought it would be interesting to see just what an average survey crew can survey per hour.

I consider myself an intermediate level sketcher and I've been getting about 100 feet per hour. Doesn't seem to matter much if it's a vertical, horizontal, large passage, or small passage. I just started using Auriga and I believe that will bump me up another 50 feet per hour(I don't have to use a protractor anymore ). Hopefully, I'll get faster as I gain experience.

Once, I was on a crew of 2 that surveyed a little over 200'/hour. I ran instruments and he sketched. No backsights.

[robcountess]

We're pretty laid back in Canada, nobody does backsights and 95% don't sketch to perfect scale (eyeball scale only) so typical survey speed is 50-150 m/hr depending on the passage and the crew.

[Jeff Bartlett]

nobody does backsights and 95% don't sketch to perfect scale (eyeball scale only)

I hope your cartographers are stocked up on Molson and Labatt's!

[robcountess]

Actually a lot of them are stocked up on BC bud, and I don't mean Budweiser Not me though, I'm the nerdy one.

[Ralph E. Powers]

Actually a lot of them are stocked up on BC bud, and I don't mean Budweiser Not me though, I'm the nerdy one.

What? You saying that nerds don't drink? I'm a nerd and that's a in ... ain... ah insull..*hic*... ai insul... th-thats j-ju- just rrruude shir.

[Jeff Bartlett]

somewhere north of here, Luc le Blanc is banging his head on a desk.
and now, back to your regularly scheduled topic!

[robcountess]

Yeah, I'm thinking of switching to Auriga too. They gave us a PDA at the start of med school and I don't use it for anything else. Only problem is they might ask for it back in 2 years but the rumour is we will get to keep them.

[Lava]

I sketch 50 - 100' per hour, including cross sections and running profile, and I thought that was super-slow! If I went to Canada and didn't have to do backsites and I could just eyeball everything I could probably double that.

[Marbry]

That's going to vary greatly depending on the passage. If it's big featureless borehole, we can do 500' or so in about an hour easy.

If it's nasty, twisty little passage where the long shots are anything over 10' the rate will be somewhat slower.

[Rick Brinkman]

Wow! Guess I missed it. I thought nobody had responded to this thread at all.....

One of the reasons I brought this up, was for estimating how long a cave project would take...plus I was just curious. In my experience, seems like 100'/hour/sketcher seems to work out about right. That is doing a plan, running profile, and crossections without doing backsights.

[NZcaver]

Just 2 feet. Often elbows, knees, and stomach too.

Seriously, for me it depends hugely on what type of cave in what region - and who I'm surveying with. But I'm not usually the sketcher.

[Jep]

Times and distances vary on where in the cave you are surveying.

Frog Hollow. 1622' in 44 stations and 4 hours the first day with four people. 571' in 12 stations and 5.5 hours with three people. 405.5' the first day (boarhole passage) and 103.5 feet the second day (nastly 18-36" high cold stream passage).

Jep.

[Jeff Bartlett]

Those of you who are averaging 200' or more per hour, I'd very much like to see what these sketches look like. I know a lot of places where 2500' surveys were the norm 20 years ago, and many of those surveys are being re-sketched in projects that are still active.

This isn't to say that it cannot be done; I managed 150ft/hr of highly detailed sketch in borehole passage just this month. However, it's worth noting that different groups certainly sketch to different standards, and that sketching is most certainly not a race!

[devil dog grotto]

i survey 50' to 100' an hr and measure all areas and then go home and recopy the sketch on another book and add my notes and details so it is more ledgable and recopy compass bearing using military compass flat mapping tool that you use for a topo map. it works and turns out quite well.

[Pat Kambesis]

If I'm on a 3-person team that is experienced and efficient (where I don't have to tell them what to do, they know how to run an efficient survey line and they don't make me wait while they are marking stations), I can get between 200-250 feet/hour - sometimes more depending on nature of passage. Thats doing plan, profile and cross sections, hand-plotting to scale with good detail, with backsites, shot-length average 50 feet. If I have to divert my attention from the sketch then the average drops - how much of a drop depends on how much I have to interact with the survey team (for anything other than confirming data and requesting a few splays). If I split up the sketching duties (have someone else do cross sections and sometimes profiles) then that average goes up even more. On a recent survey trip, we were mapping a kilometer a day in very big passage - and were able to pull that off because we split up sketching duties.

I don't consider myself to be a speed-sketcher, but I do work very hard on being as efficient as possible and thats is really the key. For me, efficiency means:

total concentration on the sketch i.e. can't talk while I'm sketching

having the book set up such that I don't have to constantly be flipping through pages (rubber bands on both sides of notebook to keep active pages handy)

keeping the protractor attached to the book so its always handy and never gets lost or misplaced

having handy several good mechanical pencils with big, effective erasers (cheap pencils have cheap erasers)

knowing map symbols by heart

always putting north arrow and scale on each sketch page so there is never any confusion

working only one station at a time

being familiar enough with the proctrator that plotting the survey line is second nature

receiving the data in the same order for every shot and repeating data back to make sure I heard correctly,

insisting that the survey team identify each number they give to me i.e. distance, front site azimuth etc. This assure that I am recording data correctly - its much more efficient to plot it right the first time, than having to erase and replot.

getting passage dimensions immediately after the distance reading (so I can start drawing walls immediately)

limiting shot length to 50 feet or less (though I do make exceptions). For longer shots, I might like the tape left on the floor so I don't have to guess where I'm at on survey line

I like to have along 8.5 x 11 rite-in-rain paper - for big passages or rooms, or very mazy sections of cave, its easier and faster to work on one page than to have to flip back and forth between several pages. If I don't have big paper, I may duct tape several sheets to make one big sheet. If I KNOW I'll be in this type of passage I'll also use a clipboard (with protractor attached, pencil pocket taped on back) with the big paper.

The efficiency of the rest of the survey team is also important - that means that they work such that the sketcher is NEVER waiting on data from them.

Each of the above saves a few seconds here and there during the survey - and those seconds add up quickly and translate into lots of survey footage.

I think the "original" question was aimed at trying to figure out how long it would take to map a cave - and the answer totally depends on experience level of the survey teams.

pk