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# Traverse Along with New Road

Dear All,

I have to start New Traverse on a Road with Total Station, Sokkia CX 105. Two Perment Bench Marks already established at start point and other are after every 5 KM. Perment Bench Marks are established by our Client with GPS. I know when i will  run my traverse with Total station, it will not give same coordinates on Fixed Bench mark (which is already established with GPS at every 5KM) ,Can any one tell me, how i can close my Total station run traverse on every 5KM Perment bench mark. I mean to say that what will be formula by manually to close it............

This Content Originally Published by a land surveyor to Land Surveyors United Network

Views: 506

### Replies to This Discussion

The Helmert transformation, should give you a "best fit" scenario and you can use it with a free patch in autocad civil 3D
You need to calculate the combined scale factor and apply that to either your ground coordinates or take the CSF and subtract it from 2 and apply that to you GPS coordinates

Tahnks, Mr. Jason Graves and all who replied on my post.
This question asked to me in a job interview. I know GPS
's established bench marks have CSF, Combine scale factor, Surveyor used it in his Total station survey to established new control points. But when he reached at last Bench mark (which was established by Client with GPS) he found (for example 0.30 cm in Easting and 0.10 Cm difference in Northing) , how surveyor will adjust all his Total station done Traverse survey to get last fixed point  Northing and Easting , I know some software can do this but mostly are not free. Does any one have its munual formula or method with which i can adjust whole traverse.
This Alignmet traverse should be closed at last given point...\

If you have already done the traverse with no scale factor involved and you know what the scale factor is. Also I'm assuming that your instrument stores all traverse data including slope distance and vertical angle then you can just manually apply this calc to get your distances with the scale factor applied.

Where:

A= Scale Factor

B= Vertical Angle

C= Slope Distance

Once you've re-calced your distances you can re-calc your Traverse to see if it closes.

The only thing can't remember is what the units for the scale factor is so you'll have to have a play to find out what fits.

The advice above is good but I would also add the following:
Here, in the US our gov. (NGS) has numerous free downloads for working with GPS data. Did you check with your government to see what assistance they may offer. Actually, you may be able to get the NGS programs on line. They are pretty good but I don't think as "user friendly" as some of the commercial offerings. Also, I might be preaching to the choir, but if you certify anything, be sure to reference your source of data. The error could be & at least part of it, is likely in the control set by others. Every measurement has an associated error, hopefully very small.
Mr. Robinson,
The scale factor doesn't have units, it is a ratio. Here, we get data in meters & international feet. The scale factor works with both & will also work with other units if properly converted(convert the coordinates to the desired units). If you only get survey data in one unit where you are, consider yourself lucky. Using the wrong conversion factor will result in a very large error. There is only about one ten-thousandths of a foot difference between the US Survey foot & the international foot. Hardly noticeable in most ordinary surveying but if you use the wrong conversion factor with the large numbers associated with State Plane coordinates, you usually wind up with a large error.

Hi Charlie, What I should have said is number format and not units. When I was out in the field around 10 years ago and mostly  used Leica Total Stations and say for example I wanted to enter a Prism constant of 25mm. We all know that in metric units this is 0.025mm yet the instrument only required you to enter a whole value of 25 and that was it. I'm almost certain from what I can remember that the entry for scale factor is set up in the same format for this particular instrument. I'm not too sure how it is for other instruments and the word units means to me the following: millimetres centimetres and meters as I've never really had to use feet and inches before.

Thanks.

William,
I envy you the luxury of having a standard system of units. Architects & some others still use inches. I have never known a surveyor to use inches. We use decimal feet for the most part. Feet & inches is an abomination. The excuse Architects use most often is that it is for the tradesmen as they don't understand decimal fractions or other units. That's BS as tradesmen are plenty intelligent enough to understand any system of measurements. We are gradually moving toward the SI system of measurements but change comes slow. The official unit of measurements for the public lands of the U.S. is the Gunther's chain. Gunther was an English clergyman & mathematician (1581-1628) & his system was the first to use decimal fractions based on units of 10. Many old surveys, particularly those done in areas originally surveyed by the government, were in Gunther's chains, called simply chains. Few surveys are actually measured in chains these days. Old surveys measured in chains are generally converted to feet or meters for resurveying or subdivision.

We do still have that problem with old English feet and inches which is still used by Earth works firms. They'll talk to each other in meters for bulk earthworks until it comes to final trim and then everything is spoken in the language of inches :-)

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