1 MARCH 2000
2. ESTABLISHING CONTROL POINTS AND POTENTIAL CORRIDORS.
a. Control points serve to limit location alternatives. They represent places through which the railroad
must pass or would ideally pass.
b. The most obvious control points are end points: the terminals and the connections with the
commercial railroad. Intermediate control points may be established by facilities or geographic features
that must be avoided, such as firing ranges, areas that cannot be drained well, or environmentally
sensitive areas. Control points can also be places that offer significant construction and operating
advantages, such as narrow or shallow river crossings and areas with naturally good drainage.
c. After control points are marked on contour or aerial maps, approximate boundaries of potential route
corridors are sketched. More control points, and other information needed to define a specific route, are
identified during the next stage (reconnaissance).
a. The reconnaissance is a quick examination of a wide strip of land between control points the strip
representing rough boundaries of a potential line location. Several routes (or alternatives for portions of a
route) may be examined.
b. The purpose of a reconnaissance is to identify routes that might allow the easiest construction effort
consistent with the purpose and requirements of the railroad.
c. Contour maps, aerial photographs, and previous survey information are good sources to use during
the reconnaissance. A small set of maps and diagrams (with control points and potential routes
identified) is convenient for field use. The information gathered during the reconnaissance can then be
transferred to larger maps and computer files back in the office.
d. The reconnaissance may be done by any means appropriate for the terrain and distances to be
covered: walking, driving, or from the air. Generally, take note of terrain features and anything that might
affect route location and construction. Look especially for:
(1) Landmarks for referencing the location.
(2) Additional control points.
(3) Areas of potentially easy or difficult construction.
(4) Roads and utility lines to be crossed.
(5) Waterways or ravines to be crossed. (Estimate length and height of bridges).
(7) Soil conditions and geological features.