Equipment And Testing For Field Engineers In Construction

Equipment and Testing for Field Engineers in Construction

In this blog, I’m going to talk to you about how you can enable your field engineering team and your field engineering program by making sure that you have calibrated and functioning equipment. And if you don’t, you’re going to be out there, oh my gosh, I’ve seen this so many times, waste so much time running level loops, shooting elevations, running a traverse, and you’re like, “What is going on?” And you’re so frustrated, only to find out that something went wrong.

So, I’m going to talk to you about best practices right now.

The Pain of Uncalibrated Equipment

Here’s what happens when you don’t have calibrated equipment. You run level loops and they don’t close. You shoot elevations and they’re wrong. You run a traverse and the numbers don’t make sense. You waste hours, maybe days trying to figure out what’s going wrong. And then you discover: your tribrach is out of calibration. Or your automatic level is off. Or your prism pole is wrong. And now you have to redo everything.

And here’s the deeper problem: if you don’t catch it, you lay out the building wrong. Columns are out of tolerance. Walls are out of plumb. Elevations are inches off. And now you have rework. Delays. Frustration. And the schedule collapses.

So you’ve got to make sure that you’re using your equipment in a tested and calibrated manner.

The Ideal Setup: FE Bullpen with Testing Area

So when you begin your field engineering program, I’ve said this multiple times, but I want you to have an open office space FE bullpen. And remember, that’s not a dig. It’s not like, “Oh, why do us grunts have to be out in this open office space?” Open office spaces, in my opinion, obviously, are the most intelligent form of collaborating in an office of all. I loathe separate offices and closed doors. All it does is tear down trust.

So if you have an open office space in an FE bullpen and you’re the only one, then you’re the only cool group in the office. But typically what you’ll do is you’ll have a little area in the FE bullpen and then outside, let’s say your overall trailer, let’s say that’s the outside of your trailer and maybe there’s a sidewalk or there’s like an area over here where you can go set up some stuff. You’re going to have some testing and inspection requirements for your equipment, your field engineer equipment specifically.

And I’m going to go through these one by one. First of all, this is in Wesley Crawford’s book, Construction Surveying and Layout. It will also be in his fourth version, which should be out in the next couple of months. But the bottom line is you need to make sure your equipment is in good working order. Now, I’m not going to cover this in detail, but I’ll give you the high points and then point you to the reference material.

Total Stations: Cleaning and Calibration

Let’s first talk about a total station. There is, inside the book, ways to check your angle measurement for your vertical and horizontal angles. There’s two specific tests that I like in there where you can make sure that it’s in good working order. And typically that’s in chapter 10 in the book in version three.

Typically, you don’t have to do these angle checks because most of the time your total station will be in good working order. Let’s say you have a total station on a project. Before you go to the next project, I would have it sent into the survey shop to get cleaned and to get calibrated. And if you do that and basically take really good care of it, make sure you’re using the lens-appropriate cloths and cleaning wipes, not Windex and not your fingers, and that you’re not putting the total station inside of a case when it’s wet to where it gets into the optics and affects the inside next to those lenses inside the actual machinery. As long as you’re taking good care of it and you’re not dropping it and you’re not holding it over your shoulder, you never hold these things over your shoulder like this, you should be good to go.

Now, if you feel like it got bumped or it fell over, obviously take it in to get cleaned and calibrated again. But typically you don’t have trouble with total stations. Now, I always want you to have a 3-second gun or better. You can’t ask surveyors or survey shop owners anything about this. They’ll be like, “You don’t need that, blah blah blah.” Yes, you do. If you’re going to close the traverses and do the kind of layout that I expect and that Wesley Crawford expects for construction control, you’ve got to have really good equipment. You’ve got to maintain them.

Automatic Levels: How They Work and How to Test Them

Now, your automatic level, which some people call a builder’s level. I don’t know that that’s incorrect, but it’s an automatic level because it’s got an automatic internal compensator. And so, what that means is that you will have a prism that’s literally dangling with little wires. That’s why Wesley Crawford in his book says, some of the older instruments had a little lever or button, but you tap the instrument and it should jiggle. It means that this is freely moving. And what it does, it aligns, based off of gravity, any small misalignments in your line of sight.

So, you need to make sure that your automatic internal compensator is working. And you’ll also do a number of other things to make sure that you get rid of parallax and that you have this in focus. But the bottom line is that your level bubble here on the actual housing, the tribrach, has to be calibrated to make sure that this is level.

One of the main things that you’ll do is you will do what’s called pegging a level. So, you will set up your level here in the middle between like two poles that are 200 feet apart. You’ll mark a line, mark a line, and then you’ll come set up over here. And you will mark a line, mark a line, and the distance between these two should be within about an eighth of an inch. They should be equal on both sides.

See, if your automatic level is off, it won’t go like this. It will go like this. Right? So, if you have an automatic level that’s wrong and you’re perfectly between those poles and you make marks and then you get closer to one, you’ll see how those differences start to increase from pole to pole. So you can do pegging a level. And back at the shop, what they’ll do is they’ll just automatically have a little metal plate that’s perfectly level and they’ll make sure that that little level bubble is perfectly level and that it’s sighting properly.

I’m exaggerating a little bit, but I’d say about 15% of the time you’ll get an automatic level right out of the shop that’s not in good calibration, and you need to check it. And if you drop it or there’s a problem or somebody adjusts this level bubble or you’re just not shooting properly, you need to go peg that level. And I actually would recommend that you peg that level every two to four weeks anyway as a standard form of practice.

The Problem with 4-Foot Prism Poles (Avoid Them)

A couple of things that really go wrong quite a bit. Your 4-foot prism poles you shouldn’t be using too much because even if a surveyor argues with me. In fact, let me just say something funny. There was a surveyor that actually worked on a Hensel Phelps job that read our book, Elevating Construction Surveyors, and gave us a bad review because he didn’t like following all of the rules and best practices and made fun of us and gave us a one-star rating. And so that book had a bad rating for a while. And now, naturally, over the years, it’s a 4.7. So, there you go, in your face. It’s an awesome book and people are really doing well with it.

But the problem is surveyors are some of my favorite people in the world, but they’re also some of the most arrogant and cocky and know-it-all people in the world. And they think because they can run a total station that they know everything. And that’s just not the case. And it’s very hard to find a surveyor that understands proper construction tolerances.

From a 4-foot prism pole from the top to the bottom, it’s not uncommon to be 3/16 to 3/8 off. That level bubble is not that accurate. But even if you’re using it like let’s say for general staking, rough staking, you’re locating your trailer, something like that, you need to make sure that it is in good calibration. I’m not going to list any brand names here, but they have a True Plumb. You’ll get it fixed inside the office to where it’s perfectly plumb. You put the 4-foot prism pole in there, and then if the bubble isn’t reading properly, you know you have a problem. There’s other ways to handle it, but these quite often need to be checked.

Tribrachs: 50% Wrong from the Shop

Let me give you one other one, which is a big one because it’s used for precise work. When you’re on a tripod, you’ll have over the head, you’ll have a tribrach that literally links you to a prism. Typically, I like to use the omni prism. What it does is it has an optical plummet and it will sight down to a point and it will level you and it will bring your target up higher and it’s better than a 4-foot prism pole.

But, and this is real, about half the time, 50% of the time that I order a tribrach from a survey shop, it’s out of calibration. And I’m not going to go into too much detail, but I think you’ll find this interesting that if you want to calibrate and actually bring into calibration your tribrach, you set it up perfectly like it’s a total station, and then you literally trace the outline on the head of the tripod and put it on the point. Then you turn it, and I believe it’s 120°. Yep. And you put it back in the trace line, level it up, and it should hit the point.

If it doesn’t, it’ll give you a different dot mark. Then you move it 120°, level it, and you’ll get a different dot mark. And then you’ll end up with three dots down there. And the middle of those three is actually where the level tribrach should be sighting. So, you move it to the middle, make it level there, and it will start to perform with the optical plummet right over the point accurately. And then you can test it, test it, test it until it’s perfect. Or you can take it into the shop.

But the bottom line is total station, typically good. Levels you have to test. The prism poles you have to test. The tribrachs you really have to test.

Steel Chains and Nylon Tapes: The Testing Area

The last thing that I’m going to say is that your steel chains, which means your 100–200-foot chains, you will need a point. That’s why I mentioned on the sidewalk a point here at zero and then at 100. Actually, this is a challenge for you. I want you to shoot 100 feet with a total station. Measure 100 feet with your chain with the right tension, no sag, and with the right temperature corrections. And then I want you to use one of those silly nylons 100-foot tapes. And you’ll see that the silly nylon ones can be up to 3/4 of an inch wrong.

And so, if you’re going to do any kind of measurement up to 100 feet, I want you to have this testing area on the sidewalk. And then these you can do over here in this other area and be very successful. So, I want this whole thing set up to where you can go test your equipment at any time. If your project needs superintendent coaching, project support, or leadership development, Elevate Construction can help your field teams stabilize, schedule, and flow.

Equipment Testing Checklist for Field Engineers

Here’s the testing schedule:

• Total stations: Clean and calibrate between projects – Send to survey shop for cleaning and calibration before moving to next project. Take good care with lens-appropriate cloths (not Windex or fingers), don’t store wet in case, never hold over shoulder. If bumped or dropped, recalibrate. Always use 3-second gun or better.
• Automatic levels: Peg every 2-4 weeks – About 15% come from shop out of calibration. Set up between two poles 200 feet apart, mark lines, compare distances (should be within 1/8 inch). If dropped or level bubble adjusted, peg immediately. Standard practice: peg every 2-4 weeks.
• Tribrachs: Test immediately (50% wrong from shop) – Half the time tribrachs come from survey shop out of calibration. Set up, trace outline on tripod head, turn 120°, level up, check point. Repeat 120° twice more. Three dots show where tribrach should sight. Move to middle, level there, test until perfect.
• Steel chains and nylon tapes: Test on sidewalk – Create testing area on sidewalk: point at zero, point at 100 feet (shoot with total station). Measure with chain (right tension, no sag, temperature corrections). Compare to nylon tape (can be 3/4 inch wrong). Use testing area regularly.

A Challenge for Field Engineers

Here’s what I want you to do this week. Set up your testing area. Create points on the sidewalk at zero and 100 feet. Peg your automatic levels. Test your tribrachs (50% are wrong from the shop). Test your chains and nylon tapes. And establish a testing schedule: total stations between projects, automatic levels every 2-4 weeks, tribrachs immediately when received, chains regularly.

And if you want more details, it’s in the Field Engineering Methods Manual. You got to make sure that you’re using your equipment in a tested and calibrated manner. As we say at Elevate, field engineer equipment testing: peg levels every 2-4 weeks, check tribrachs (50% wrong from shop), test chains on sidewalk, calibrate total stations yearly.

On we go.

Frequently Asked Questions

How often should you peg an automatic level?

Every 2-4 weeks as standard practice. Also peg immediately if dropped, level bubble adjusted, or not shooting properly. About 15% of automatic levels come from the shop out of calibration.

Why are tribrachs often out of calibration?

Because 50% of the time they come from the survey shop out of calibration. Always test tribrachs immediately when received by setting up, tracing outline, turning 120° three times, and checking if optical plummet hits the point.

Why avoid 4-foot prism poles?

Because from top to bottom, they’re commonly 3/16 to 3/8 inch off. The level bubble is not that accurate. Use omni prisms with tribrachs instead for precise work. Only use 4-foot prism poles for general staking.

How do you test steel chains?

Create testing area on sidewalk with points at zero and 100 feet (shot with total station). Measure with chain using right tension, no sag, temperature corrections. Compare to nylon tape (can be 3/4 inch wrong).

When should total stations be calibrated?

Between projects. Send to survey shop for cleaning and calibration before moving to next project. Also recalibrate if bumped or dropped. Always use 3-second gun or better for construction control.