Figure 3-3.The road plan.
The drawing of the proposed center line is then
given to a final location party, which stakes in the center
line and curves. With the approval of the engineer, the
party chief may make changes in alignment of the center
line, but the changes must be recorded.
Once the final location is determined, all
information and changes pertinent to the location are
used to prepare a second and final drawing, showing the
final center-line location, construction limits, all curves
and curve data, station marks, control points, natural and
man-made terrain features, trees, buildings, and
anything else that is helpful in construction. This
drawing, known as a road plan (fig. 3-3), is a
birds-eye view of the road and shows what you
should see from a position directly above. The road plan
is drawn on the upper portion of plan-and-profile paper,
using any scale desired. The bottom portion of the
plan-and-profile paper, which, as you know, is
composed of grid lines, is reserved for drawing the road
The road plan, or
location and length of
plan view, shows the actual
the road measured along the
center line. The length is determined by station points,
which are set at full station (full stations are 100 feet or
100 meters apart), half station, or one-tenth station
intervals. Odd-station points are set at major breaks in
the terrain. Referring to figure 3-3, you see the manner
in which the beginning station (0 + 00) is shown, and
you also see the manner in which the full stations and
the partial stations are shown. Recalling your study of
the EA3 TRAMAN, you know, then, that the distance
from the beginning station to the last full station shown
(13 + 00) is 1,300 feet.
All man-made and natural objects, such as trees,
buildings, fences, wells, and so on, are also plotted on
the plan if they are in the right-of-way or construction
limits. (Right-of-way is the land acquired for the road
construction.) Identification and location of these
objects are taken from the surveyors notebook Their
location is determined by a station number and distance
from the center line. All measurements and distances are
made perpendicular to the center line of the particular
station unless otherwise noted.
The road center line consists of straight lines and
curves. The straight lines are called tangents, and the
curves are called horizontal curves. These curves are
used to change the horizontal direction of the road. All
information necessary to draw a curve should be
furnished by the engineer or taken from the surveyors
notebook. The necessary information is known as curve
data. Below is the data for curve No. 1 in figure 3-3 and
an explanation of the terms.
R = 240.11'
T = 132.53'
L = 243.48'