Figure 5-18. Taping pins
h. Leveling Rods. A leveling rod is a wooden rod that is used to measure the vertical distance
above a point. This point may be a permanent elevation (bench mark), a temporary bench mark (a
turning pin or stake), a man-made object, a constructed surface, or a natural point on the ground surface.
(1) Use. The leveling rod may be read directly by the instrument man sighting through the
telescope, or it may be target read. Conditions that hinder direct reading, such as poor visibility, long
sights, and partially obstructed sights (through brush or leaves), sometimes make it necessary to use a
target. A target is also used to mark a rod reading when numerous points are set to the same elevation or
a certain constant grade is needed from one instrument setup. In Figure 5-19, view B shows a rod with
metric measurements; the graduations of the rod are in meters, decimeters, and centimeters. The targets
that are furnished with the metric rod have a vernier that permits reading the scale to the nearest
millimeter. The metric rod can be extended from 2.0 to 3.7 meters.
(2) Types. The different types of leveling rods are discussed in the following paragraphs.
(a) Philadelphia Rod. The most popular of all is the Philadelphia rod, which is a
graduated two-section wooden rod (see Figure 5-19, view A). It can be extended from 7 to 13 feet and
each foot is subdivided into hundredths of a foot. Instead of each hundredth being marked with a line or
tick, the distance between alternate ones is painted black on a white background. Thus, the value for
each hundredth is the distance between the colors; the top of the black increment is even values and the
bottom of the black increment is odd values. The tenths are numbered in black and the feet are
numbered in red. This rod may be used with the level, theodolite, and hand levels on occasion to
measure the difference in elevation or it may be used for topographic land surveys.
Targets for the Philadelphia rod are usually oval, with the long axis at right angles to the rod and the
quadrants of the target painted alternately red and white. The target is held in place on the rod by a C-
clamp and a thumbscrew. A lever on the face of the target is used for fine adjustment of the target to the
line of sight of the level. The targets have rectangular openings about the width of the rod and 0.15 feet
high through which the face of the rod may be seen. A linear vernier scale is mounted on the edge of the
opening with the zero on the horizontal line of the target for reading to thousandths of a foot. When the
EN0591
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