(1) Closed Traverse on a Starting Point. A traverse which starts at a given point, proceeds to its
destination, and returns to the starting point without crossing itself in the process is referred to as a loop
traverse (as shown in the example in Figure 3-14). Surveyors use this type of traverse to provide control
if there is little existing control in the area and only the relative position of the points is required. While
the loop traverse provides some check of the fieldwork and computations, it does not ensure detection of
all the systematic errors that may occur in a survey.
(2) Traverse Closed on a Second Known Point. A traverse closed on a second known point
begins at a point of known coordinates, moves through the required point(s), and terminates at a second
point of known coordinates. Surveyors prefer this type of traverse because it provides a check on the
fieldwork, computations, and starting data. It also provides a basis for comparison to determine the
overall accuracy of the work.
d. Fieldwork. In a traverse, three stations are considered to be of immediate significance. These
stations are the rear, the occupied, and the forward. The rear station is the station that the surveyors who
are performing the traverse have just moved from or a point to which the azimuth is known. The
occupied station is the station at which the party is located and over which the instrument is set. The
immediate destination of the party is the forward station or the next station in succession.
e. Horizontal Angles. Measure horizontal angles at an occupied station by sighting the instrument
at the rear station and measuring the clockwise angles to the forward station. To measure horizontal
angles, make instrument observations to the clearest, most defined, and repeatable point of the target,
marking the rear and forward stations. Measurements should be repeated according to the required
f. Distance. Use EDME to measure the distance in a straight line between occupied and forward
stations. Measurements are repeated according to the required specifications.
g. Traverse Stations. Surveyors select sites for traverse stations as the traverse progresses.
Surveyors locate the stations in such a way that at any one station both the rear and forward stations are
h. Station Selection. The number of stations in a traverse should be kept to a minimum to reduce
the accumulation of instrumental errors and the amount of required computing. Short traverse legs
require the establishment and use of a greater number of stations and may cause excessive errors in
azimuth. Small errors in instrument centering, station marking equipment, and instrument pointings are
magnified and absorbed in the azimuth closure as errors in angle measurements.
i. Station Markers. Station markers are usually 2- by 2-inch wooden stakes, 6 inches or more in
length. These stakes (or hubs) are driven flush with the ground. The center of the top of the hub is
marked with a surveyor's tack or an X to