That depends. Type of edmi how it was designed and the wave lenth of the signals. The accuracy of said edmi. The centering ability of edmi and the target as well as the targets prism accuracy. Versus the tape type and accuracy and the know how to use it. Both tools need temperature corrections. And tape needs tension swag corrections. I would say you can be very accurate with a tape. At greater distances than 100 ft. It has been proven. Now under 50 ft. I would personally if doing something that required very small errors would probably prefer a good steel tape.
Our Land Court used to require that at least one line be measured with a tape and the EDMI. They have relented and now ask that the EDMI be calibrated (on the baseline) before and after the project.
@not-my-real-name That was not uncommon. However thats not what you stated. You simply stated that tape was more accurate than edmi at distances under 50’ and title is fish tales. Edmi of today are much better than years ago. I remember the specs of a sokkia and it was 3mm + 2ppm and even had a statement that stated under 100’ was not recommended. Thats about a hundreth of a foot I have no reservation of being that accurate at all with proper steel tape and corrections applied. If you take that Sokkia from the 90’s plus set up error and not even include the target error the tape wins. Now the wavelength of that design was not good at short distances it would repeat plus or minus a few hundredths. Now did we measure with it at short distances yeppers a lot. But when it had to be tight we used a steel tape. That had also been calibrated at the edmi baseline they always had a mark for tape calibration back then as well as the marks for edmi calibrations. I don’t know if they set the tape mark anymore though on new baselines. Where i am located its not required to even go to a baseline unfortunately. Manufactures calibration is sufficient. Every state is different. We went twice a year when I surveyed in Colorado. My first year the first time i went that year i did 18 total stations not in one day for sure. i could get 2 a day then return with same 2 next day. Was a unique experience for sure. To do it per the book it took a little time for sure.
More than thirty years have passed since 1990 so the statement is likely not relevant today. My post was meant to imply that saying the tape is more accurate is a fish tale.
Our Land Court used to require that at least one line be measured with a tape and the EDMI. They have relented and now ask that the EDMI be calibrated (on the baseline) before and after the project.
Our Land Court used to require that at least one line be measured with a tape and the EDMI. They have relented and now ask that the EDMI be calibrated (on the baseline) before and after the project.
Every project?
Yup. From the 2006 Land Court Manual of Instructions:
2.1.3.3.3. Calibration. All linear measurements shall be taken with a properly calibrated measuring device. A record of the calibration results shall be maintained for future reference. (See 250 CMR). The Survey Division may request a review or a copy of said record. (See § 2.1.3.4.7.)
2.1.3.4.7. Electronic Measurements. When using EDM instruments, suitable checks include the use of calibrated NGS certified baselines or comparison to a standardized, calibrated steel tape. When calibrated baselines are used, copies of the calibration records for the instrument or instruments used, preceding and subsequent to the survey, signed and sealed by the responsible surveyor, must be submitted with the Filed Plan. For comparison to a standardized steel tape, one traverse line over 450 feet must be measured with both EDM and standardized steel tape. This 450-foot line should be a part of the closed field traverse or an extension of one of the traverse lines and notation must be made on the plan to indicate the results of both measurements. When it is not practical to measure a 450-foot line in the closed field traverse, a temporary comparison baseline over 450 feet long can be established using the same equipment and certified by the surveyor.
Only Registered land, which is a small percentage of properties in Mass.
I haven't done a Land Court survey in a while, but I can remember steel-taping a 450'+ traverse line, using temperature correction and that device for the correct tension.
Most of the time, let's just say the distances matched the EDM within a hundredth or two.
@not-my-real-name I remember using that calibration line in the highway median west of Boston several times. Was it Hwy 9? I cannot recall but it was on the way to "Woosta" wasn't it?
@not-my-real-name I remember using that calibration line in the highway median west of Boston several times. Was it Hwy 9? I cannot recall but it was on the way to "Woosta" wasn't it?
I-290 in Marlborough. Nearly impossible (expensive) to use now because MassDOT requires extensive signage and cone layout as that stretch of highway is very busy. Try using it now without a permit and all the required stuff, and they'll send the state troopers along to pay a visit very quickly.
I still have chaining pins 3 and 1/4 set. Chain holder for those with soft hands and 2 tensioners. They might need to be checked. I probably still have a few if the have not busted but the temp gauge that could be snapped onto a steel tape. I can barely get folks to check a measurement on a house with a tape. They would probably have a heart attack if i required them to chain a traverse or boundary line. Lol. Measuring with a steel tape can be very accurate even over very long distances. I have one 300 ft add chain steel tape still in the box and one i use to layout my paddocks. And fences. I basically have taped my whole 7 1/2 acres squaring up fence around house and around property. I was not surveying for someone at the time. I did rent a level and laid out and designed on paper a area to fix a drainage problem. Mostly fixed but still waiting on state to fix the culvert that flows in the wrong direction.
