Have been quoting several highway layout jobs in recent years and never seem to get them. I was wondering if I'm "behind the curve" in terms of utilizing technology to aid in construction layout. These things are generally hard to stake b/c as we all know every contractor does it differently. Anyhow, we have a 2 man crew and a GPS crew (1 man, sometimes 2 man) and we usually bid to stake some things with one or both crews. One thing I seem to notice is a lot of vertical work being done w/GPS. How much do you do w/GPS? We typically see project control every 1,000' or so. How do you set intermittent benchmarks? Are you using GPS to do this? When staking and grading for say curbing, what are your techniques? We typically do it conventionally with a total station, then come back w/a level to grade the stakes (which is what most contractors around here want, have only done blue tops once in my career). I actually saw a crew grading stakes w/a total station about 2 years ago. I'd do it for dirt work, but they were doing it for curb and gutter. Anyhow, trying to figure out why we are missing the boat on some of these jobs. Thanks for the responses.
We're not in flordia but I cannot see being competitive in highway layout using a level to grade every stake. Robotics are the only way to be fast and accurate enough. Set horizontal control with gps run digital level through. i think people don't trust total stations for layout because they don't calibrate the tilt and collmination enough I often do mine 1 or 2 times a day depending on temperature and check face 1 and face 2 on every setup. Using a robot and under 500' setups the v error should be more than manageable .01' or .02'. I think a fully decked out efficient construction crew would cost 75,000-100000 to outfit at a minimum with new equipment.
Not in Florida, but I set enough control to be able to use a robot for concrete or drainage. Rough staking with GPS. Usually set horizontal with GPS, then run either level or trig levels for elevations on the control, then it's all robot and resections.
Certainly not from Florida but in the last two years 80% of our curb stakes have been set with GPS with 0 problems. The other 20% was conventional staking using a robot and you can't tell the difference at all except that one was done 50% quicker.
You've probably got a little more grade change where you are than where the Florida fellow is. I'd be scared to death to set grades on a Florida road with GPS.
There is a great deal of variation in technique as you move sites (or states). If I'm doing asphalt at 2% grades will be done with the robot. Concrete at 0.2% I'm using a level. It's a right tool - right job and standard of care decision.
My proposals are based on methods I am able to meet spec with. If I don't get them because someone is doing it different I look at my procedure, not my price...
It's been about 12 years since I worked in Florida. I would rough stake with a total station. Then hub&tack for horizontal with a total station. next to it a grade stake to the nearest foot set with a level for final staking. Right before I moved to god's country I used a robot to set the grade stakes but came back through to check with a level. Most of the time I would use a linker rod when setting grade stakes. I wouldn't trust gps today for elev. I have seen too many times it says its good when it's not.
Late again here, but a fellow beerlegger who goes by Roadhand is a construction surveyor with lots and lots of knowledge on highway construction layout. Send him an email.
I don't like his hockey team (Red Wings don't like Stars 😉 ), but he's a pretty sharp guy
If you are ok with 2cm accuracy on vertical, stake curbs with GPS.
The thing is that +2cm on one and -2cm on the next results in a real world precision between the two points of around 4cm.
The thing is that even a poorly adjusted total station with say 2 cm of error at 500' (unlikely) would be off that amount in a linear fashion, assuming that the total station was looking down a road. What I mean is that one point would be -2 cm, and the next point 25' away would be -2 cm (plus pointing error).
The GPS is far more accurate across the job site, but personally, I do not like it for curbs.
> There is a great deal of variation in technique as you move sites (or states). If I'm doing asphalt at 2% grades will be done with the robot. Concrete at 0.2% I'm using a level. It's a right tool - right job and standard of care decision.
> My proposals are based on methods I am able to meet spec with. If I don't get them because someone is doing it different I look at my procedure, not my price...
:good: :good:
I will say that the wide open sky of Eastern WA makes GPS much more reliable. We work primarily on the West side, and are generally surprised every time we visit EWA with just how much more useful GPS is over there.