Over time, the Civil Engineering field has come a long way for mapping out different plots of land across the world. In the midst of the early 16th century Edmund Gunter invented a type of mapping system for Civil Engineers alike to use. He invented a chain that is 100 links long, measuring a total of 66.00 ft. and each link measuring 7.92 inches.
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| Gunters Chain |
At the start of the early 1800's the National Geodetic Survey was the backbone of the surveying field, for its Theodolite Total Station Surveying instrument. The total station is a lot more improved from the 1600s Gunter's chain. The total station is able to take vertical as well as horizontal measurements, with the help of a "rod man" holding a pole with a prism on the top end, so the operator has something to shoot at. The telescope or "transit scope" was able to flip upside down, so the operator was able to shoot their back-sight distance and double angles improving on error.
With the increase cost of this precise instrument come's a lot better readings, readings you were not able to receive with the Gunter's chain. The price of this instrument is anywhere from $5,000-$10,000 depending on the model and what other accessories you want for your instrument.
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| Theodolite Surveying Total Station |
When starting out with the Total Station, you take your sea level height and add it to your starting point which is also known as BM. You then turn your instrument counter-clockwise, so you are able to record the turning angle to calculate your azimuth. Then you shoot your next point and subtract it from your new elevation height, after that you move your instrument to the point you just shot and shoot back to the 1st point you shot. Keep these methods going until you finish back where you started, the resulting math should be right back to sea level or close to it. This is the checking method I was talking about earlier. With this station you are also able to turn the angles that are useful in the surveying world. Mostly for the computer aided design (CAD) operators who take the information you just shot and put those numbers into a map layout form. The precise angles, lengths, as well as heights any construction company needs to start the building process on a project.
The Gunter's chain process was a lot longer process because it was not done electronically, but by trigonometry using the law of cosines, law of sines, or inverse functions in order to find the different angles calculated off the horizontal. As you can see from the information above the Theodolite Total Surveying Station is what has been in use for around 120 years. As technology has increased, the world has started using global positioning systems for surveying. The Theodolite Surveying Total Station is the same device we used in my Civil Engineering course at NDSU.
As you can see I would recommend the Theodolite Total Surveying Station if you are a new Civil Engineer out there in your own company. You can also buy the GPS Surveying unit, but the prices of those vary from $5,000-$25,000. As a starting off C.E. the Total Station is for you.
References
http://en.wikipedia.org/wiki/Total_station
The Theodolite Total Surveying Station looks to be a great instrument to use and much more efficient than the Gunters Chain method. I think it is pretty neat that a guy can go take the measurements in the field and then take the data to map out the project on a computer.
ReplyDeleteI like the idea that a theodolite total station has the checking method which helps to avoid human mistakes, since the surveying data is so important in construction field.
ReplyDeleteThe Theodolite Total Station Surveying instrument was a pretty neat system. I remember using it in my surveying class and how easy it was. I think the most difficult part of the tool was getting it level which really was not even difficult at all. I know with a three person team you can work quite fast if you have one using the Total station, one holding the stick and one writing down information.
ReplyDeleteI also had the privilege of operating this instrument in NDSU's surveying course. It is fairly easy to use I'd say and definitely much more precise than using Gunther chains or an auto-level. I think it's an interesting piece of information to have the price ranges for some of the surveying equipment engineers use; shows just how valuable they are in a sense.
ReplyDeleteI like very much this idea the theodolite Total Station has the checking method..This method avoid for human mistakes..So this blog post very useful for us...Thanks a lot for that info...
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