1 MARCH 2000
(8) Vegetation type and density.
(9) Potential for future additions to the railroad (as per the Installation Master Plan).
(10) Wetlands and other environmentally sensitive areas.
(11) Snowfall and exposure to drifting snow.
e. Snow conditions along the proposed routes should be observed for at least one winter to identify
locations where drifts form. Winter aerial photographs may also be helpful for this purpose. Sites
downwind of frozen lakes should be avoided unless there is adequate room between the shore and the
roadway to install snow fences.
f. After the reconnaissance has been completed, prepare maps showing all control points and potential
alternative routes. Then, make general comparisons between the routes with respect to length, grades,
curvature, relative amount of earthwork and drainage work required, bridge work, special construction
requirements, and potential operating advantages and disadvantages.
g. If sufficient information is available at this point, recommend the best route; otherwise, prioritize the
routes. Also note any special requirements for the initial survey.
4. INITIAL SURVEY.
a. The objective of the initial survey is to obtain sufficient information to allow preparation of initial
earthwork and construction estimates and to establish a location for the track and drainage paths on
maps back at the office. When the route choice is clear from the reconnaissance, the initial and final
surveys are often combined.
b. The initial survey is done by approximating the routes as a series of tangents, taking elevations and
cross section data at selected intervals (perhaps every 100 to 250 ft) along the route. Generally, where
terrain is fairly uniform, the longer survey intervals can be used. Elevations and cross section data should
also be taken at points representing a rapid change in terrain or at other points of special interest that
may be useful to aid construction estimating. All useful landmarks should also be tied into the survey.
Stakes need to be driven in sufficient number to clearly show the survey centerline - about every 200 to
c. For cross sections (nearby elevations at right angles to the route), simply take elevations at points
that will show the shape of the adjacent terrain - local peaks, low points, and other points of special
interest. The width of the required cross section will be dictated by the character of the terrain, right-of-
way ownership, and distance needed to show local drainage and topographical features. It is not
necessary for cross sections to be of equal distance on each side of the route centerline or of equal width
at each station along the route.
d. Where terrain is open (and easily accessible) cross section data is often taken from 300 to 500 ft on
each side of the route centerline. In areas where the route location is fairly well defined, cross sections
may be much narrower; sometimes only a 50-ft wide strip is needed. The situation should govern the
choice of width.