AREA OF TRACT WITH RECTILINEAR
BOUNDARIES
The balanced latitudes and departures of a closed transit-and-tape traverse are recorded in
the table below. Compute the area of the tract by the DMD method.
Course Latitude, ft (m) Departure, ft (m)AB -132.3 (-40.33) -135.6 (-41.33)
BC +9.6 (2.93) -77.5 (-23.62)
CD +97.9 (29.84) -198.5 (-60.50)
DE +161.9 (49.35) +143.6 (43.77)
EF -35.3 (-10.76) +246.7 (75.19)
FA -101.8 (-31.03) +21.3 (6.49)Calculation Procedure:- Plot the tract
Refer to Fig. 3. The sum OfW 1 and W 2 is termed the double meridian distance (DMD) of
course AB. Let D denote the departure of a course. Then
DMD- = DMIV 1 +/V 1 + A, (3)
where the subscripts refer to two successive courses.
The area of trapezoid ABba, which will be termed the projection area of AB, equals
half the product of the DMD and latitude of the course. A projection area may be either
positive or negative.
Plot the tract in Fig. 4. Since D is the most westerly point, pass the reference meridian
through D, thus causing all DMDs to be positive.
FIGURE 3. Double meridian distance. FIGURE 4Meridian