Topography

[Cosimo]

First off, I am a Civil guy w/minimal survey field experience, so please excuse any mis use of terminology. My question is, can anyone recommend a type of instrument(total station?) that will aid in obtaining and plotting topography over relatively small tracts (less than 10 acres). This will be used to field check existing grades prior to construction. Does plotting this information require a large learning curve? Any info is appreciated.

 

[waterguy]

I've never done the surveying myself, but have been a user of the end product, so I will gladly accept any clarifications/corrections on what I write. You have two options I suppose:


1) Give your surveyor a digital copy of your site (existing conditions), and have them import their surveyed data points into your drawing. They can also generate contours for you if required.

2) If you have a suitable Civil Eng. software suite that works within AutoCad or Microstation (programs like EaglePoint and Land Development Desktop come to mind), you can import a "points file" into your drawing. A points file is typically and ASCII-text file that contains information about each surveyed point (Pt. #, Northing, Easting, Elevation, Description, etc..). The software will let you produce contours and do other

Learning to do the basic imporation of data points is not that difficult to learn, but the price of some of the software may be prohibitive if that is the only thing it will be used for.

 

[IRstuff]

Differential GPS (DGPS) surveying equipment could be used to map and survey in this type of application.

Accuracies are probably comparable to traditional theodolite techniques, but DGPS offers the possibility of getting direct digital terrain data more quickly and already in a processed state. A person with a portable computer or radio link could simply walk the terrain and record the terrain elevation data in real time. Since GPS updates at a 1 Hz rate, thousands of data points could be acquired in relatively short order. A 10 acre plot could be covered with a small tractor or ATV and you'd simply stop every 10 ft or so and get a reading directly recorded. The only post processing would be to re-grid the data for contour plots and so forth.

Traditional survey would require some setup at specific spots and post processing of the data to get the terrain elevation data. Re-gridding would also be necessary. TTFN

 

[tim216]

FIRST I WOULD DETERMINE WHAT PRICE RANGE THAT I WANT TO CONSIDER. REMEMBER GPS IS QUICK AND ACCURATE BUT IT IS AT THE TOP END OF THE COST MARKET. ANY TOTAL STATION AND DATA COLLECTION PACKAGE WOUL DO WHAT YOU WANT. YOU CAN SPEND AS LITTLE AS 8000.00 OR AS MUCH AS $30,OOO.00 IT JUST DEPENDS ON WHAT YOU WANT. IF YOU DONT HAVE SURVEYING SERVICES IN HOUSE I WOULD SUGGEST SPEAKING WITH A COUPLE OF YOUR LOCAL SURVEYORS AND FIND OUT WHAT THEY USE AND WHAT THEY MIGHT SUGGEST USING. ONCE AGAIN REMEMBER EVERYONE HAS THEIR PREFERENCE SURVEYING EQUIPMENT IS ALOT LIKE BUYING A CAR, THEIR ARE ALOT OF DIFFERENT MODELS BUT THEY ALL WILL DRIVE YOU TO THE OFFICE.

TIMOTHY DAY
SURVEY MANAGER
ARCHER WESTERN CONST.

 

[Cosimo]

Thanks for your input. I agree, we need to establish cost parameters. I did speak with two local surveyors and they each had their preference. Thanys again.

 

[KRSServices]

It all depends on how accurate you need your numbers. If you will be utilizing the numbers to estimate earthwork, then a GPS (hire someone) mounted on a quad works fine. If you are going to need them to check observed field versus final constructed grades (usually for payment items), then you will have to get a surveyor to shoot known points of reference, or benchmarks, for plotting on a plan and use in the field. KRS Services

http://www.krs-services.com

 

[KRSServices]

OOPS...I pushed submit too quickly.

Your surveyor should be able to quickly plot the information gathered. I usually request, as a component of a project, a preliminary topographical plan be developed. I alsways want to have all highpoints, breakpoints, lowpoints, accesses, structures, tree lines, utilities, property lines and monuments, unusual features and observed drainage courses plotted. From there, it is transferred to Autocad and expanded upon. Best of all, it is very inexpensive and worthwhile considering the cost to have me stumble about for weeks on site and then have to undertake plotting the info!

For me, I find it better to contract that work out to those who have chosen surveying as a lifelong profession. KRS Services

http://www.krs-services.com

 

[Cosimo]

Thanks for the input. Yes, typically we would sub this out but sometimes we don't have the time (and the boss man doesn't have the patience) to wait several weeks, in some cases, for turnaround. Even spending about 10-15 grand for a total station set up (we'll leave GPS work to you pros) will pay for itself relatively quickly.

Thanks again for the input.

 

[jheidt2543]

Does anybody do stadia any more or am I giving away my age? When we needed to verify site elevations for a construction bid, we would just take an automatic level and a Linker rod out and shoot stadia elevations around the site. In a couple of hours, with a two man crew, we would have enough information for dirtwork calculations without waiting for a hired survey crew or letting our competition in on the information. Yes, modern technology is great and fun to use, but sometimes speed is of the essence and stadia still works!

 

[KRSServices]

I used to shoot stadia too for thumb elevations, but that was replaced by those neat little hand held GPS units. Not only do you know where you are to the nearest 100mm, but you have a good idea of your elevation. The best part is that they are so darn cheap, relative to other technologies out there. I guess I dated myself a bit too. KRS Services

http://www.krs-services.com

 

[carlorom]

Handheld GPS to 100mm! Please let me have the name of that instrument?

Total stations are usually adequate for most site work and have the added advantage to be able to measure under cover etc which GPS does not - Beware of Multipath errors on GPS.

If you do drive around a site with GPS (which is great) be aware that the vehicle could bounce and thus give you erroneous height readings - It all depends on the accuracy you need. Most Total stations (such as Leica) give a points file compatible format with GPS usually readable directly into packages such as Autocad - That is in principle - in practice it does involve some learning of procedures etc.

You can also now use things such as A laser CYRAX - or as a very good replacement for the stadia an automatic level (on flat sites) but I feel that if you do that might as well have a total station which will allow for steep sites etc.

Good luck with your project.

 

[jheidt2543]

I still like the statia! For $500 dollars I can get a good quality automatic level and a Linker rod and shoot direct elevations and stadia distances. No, I can't down load that into AutoCad but, I'm not spending $15,000 or more for the total station either. It all depends on how much of this work you do, how accurate you need it, how quickly and at what expense.

By the way, my little hand held GPS, a Garmin GPS-12, is accurate to +/- 15' or so, if I use the average function of the available satallites, not survey quality. I too would like to know about one of those 100 mm ones, they can't be in the $200 range <G>

 

[KRSServices]

oops, missed a &quot;0&quot;. It should read 1000 mm, or 1 metre. I can't recall the name, but we used it this summer. I'll post later.

Regarding the bouncing. We take readings when stopped. It's firmly anchored to the rack on the quad, so the elevation stays constant. Works like a charm for large topographical areas. KRS Services

http://www.krs-services.com

 

[IRstuff]

Trimble's RT kinematic system seems to to fit the bill:

http://www.fondriest.com/products/trimble_ms750.htm

as well as:

http://www.cmcelectronics.ca/products-services/custom-elect/rtstar-GPS.html

TTFN

 

[KRSServices]

Hey, whadda ya know, there is one for 100 mm. The one we used was 1000 mm though. KRS Services

http://www.krs-services.com

 

[Smacin]

The trimble geoexplorer and the proxrs are options no?