The accuracy and quality of a survey depend upon the condition of the surveying instrument and the experience of the surveyor. The life expectancy and usefulness of an instrument can be extended considerably by proper and careful handling, stowing, and maintenance. Undoubtedly, by simply working in your rating conscientiously, you will become experienced in the proper use of the instrument.

As stated earlier, every instrument is accompanied by an instruction manual that tells you not only the proper operation and components of the instrument but also procedures for its proper care and maintenance. Study this instruction manual thoroughly before you even attempt to use the instrument.

Every transit, theodolite, or level comes equipped with a carrying box or case. The instrument and its accessories can be stowed in the case in a manner that ensures a minimum of motion during transportation. The instrument should ALWAYS be stowed in the carrying case when it is not in use.

Cleaning and Lubricating 

In general, all surveying instruments, equipment, or tools must be cleaned thoroughly immediately after you have used them. For example, you dust off the transit or theodolite and wipe it dry before placing it back in its case after each use. Remove all dust with a clean cloth. This applies particularly to the optical parts. Chamois leather is suitable for this purpose, but it is better to use a clean handkerchief than a soiled chamois leather. Use no liquid for cleaning neither water, petrol, nor oil. If necessary, you can breathe on the lenses before polishing them. When the instrument becomes wet, you should remove its case and dry it thoroughly at room temperature as soon as you get home. If you leave the instrument in the closed case, the air inside the hood will take up humidity by increasing temperature and will in time diffuse inside the instrument. While cooling off, the water will condense and form a coating or tarnish that may make any sighting with the telescope and reading of the circles difficult.

Remove any mud or dirt that may adhere to the tripod, range pole, level rod, and so forth, after each use. Clean each instrument, equipment, or tool after each use to eliminate the chance of forgetting it. This is important, especially when the surveying gear is made of a material that is susceptible to rust action or decay.

When lubricating the instruments, you must use the recommended lubricant for each part in conjunction with the climatic condition in your area. For instance, it is recommended that graphite be used to lubricate transit moving parts when the transit is to be used in sub-zero temperatures instead of the light film of oil (preferably watch oil) when its use is confined to an area with normal weather conditions. The lubricant should be applied thinly to avoid making the lubricated parts an easy repository for dust or catcher of dust.

Consult the manufacturers manual or your senior EA whenever you are in doubt before doing anything to an instrument.

NOTE: Information on tests, adjustments, and minor repairs of surveying instruments will be presented at the EA2 level.

A survey traverse is a sequence of lengths and directions of lines between points on the earth, obtained by or from field measurements and used in determining positions of the points. A survey traverse may determine the relative positions of the points that it connects in series; and, if tied to control stations based on some coordinate system, the positions may be referred to that system. From these computed relative positions, additional data can be measured for layout of new features, such as buildings and roads.

Traverse operations (actions commonly called TRAVERSING) are conducted for basic area control; mapping; large construction projects, such as military installation or air bases; road, railroad, and pipeline alignment; control of hydrographic surveys; and for many other projects. In general, a traverse is always classified as either a CLOSED TRAVERSE or an OPEN TRAVERSE.

A closed loop traverse (fig. 13-29, view A), as the name implies, forms a continuous loop, enclosing an area. This type of closed traverse starts and ends at the same point, whose relative horizontal position is known. A closed connecting traverse (fig. 13-29, view B) starts and ends at separate points, whose relative positions have been determined by a survey of an equal or higher order accuracy. An open traverse (fig. 13-29, view C) ends at a station whose relative position is not previously known, and unlike a closed traverse, provides no check against mistakes and large errors. Open traverses are often used for preliminary survey for a road or railroad.

The order of ACCURACY for any traverse is determined by the equipment and methods used in the traverse measurements, by the accuracy attained, and by the accuracy of the starting and terminating stations. Hence, the order of accuracy must be specified before the measurements are started. For engineering and mapping projects, the distance measurement accuracy for both electronic and taped traverses for first, second, and third order are 1/35,000, 1/15,000, and 1/7,500, respectively.

For military use such as field artillery, lower order accuracies of fourth, fifth, and sixth are 1/3,000, 1/1,000, and 1/500, respectively. The order referred to as lower order is applied to all traverses of less than third order.

To accomplish a successful operation, the traverse party chief must ensure that initial preparations and careful planning are done before the actual traversing begins. In the remainder of this chapter, we will discuss some of the basic procedures normally undertaken by a transit-tape traverse party.