CEMP-E
TI 850-02
AFMAN 32-1125(I)
1 MARCH 2000
Figure 6-20. Anti-Splitting Devices for Tie Ends
e. Pre-boring. Once a common practice, the pre-boring of spike holes is no longer recommended.
f. Tie Spacing. The center-to-center distance between adjacent ties will usually range from 19.5 to 22
in., with a minimum allowable of 18 in. and a maximum of 24 in. For auxiliary and loading tracks, a 21 to
23-in. spacing will often suffice. Tie spacing will be specified after a structural analysis has been
performed.
g. Concrete and Other Non-standard Ties.
(1) Concrete ties are used by some commercial railroads, particularly on lines with the heaviest traffic
volumes and in areas with numerous curves. Where used, concrete ties are in track with welded rail and
solidly supported with deep ballast sections. Concrete ties are usually not economical on lighter traffic
lines, and are usually not suitable for use with jointed rail or in track of lighter construction. Also, concrete
ties cannot be successfully mixed with wood ties. Thus, concrete ties are not recommended for general
use in military track.
(2) The use of concrete ties for certain special applications may be cost effective. The economic
benefit of these installations must be thoroughly investigated prior to the selection of concrete ties.
(3) Research and development continues on ties made with alternative materials and of hybrid
construction. None have yet proven economical for routine, general purpose use.
15. RAIL.
a. Section Designation. Rail is rolled into different sizes (dimensions) and shapes commonly referred to
as "weight" and "section." The weight of a rail is based on how much a rail weighs in pounds per yard of
length. The section refers to the cross sectional shape of the rail.
b. Selection Criteria. Selection of a rail section will be done only after a structural analysis has been
performed. Designers will determine structural requirements as well as cost and availability of rail
sections before a final selection is made.
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