CEMP-E
TI 850-02
AFMAN 32-1125(I)
1 MARCH 2000
b. Care should be taken when removing rail and OTM to prevent damage to usable materials. A torch
should never be used to cut rail, joint bars, or other salvageable materials during removal.
4. SUBGRADE AND DRAINAGE.
a. Subgrade. The subgrade will be inspected during each stage of preparation.
b. Handling and Installing Geotextiles.
(1) The maximum time for exposure of geotextiles to sunlight, from removal of the protective shipping
cover to final placement, should be no more than 7 days.
(2) Equipment should not be allowed to operate over an area covered with geotextile unless there is
at least a 6-in. cover of sub-ballast or ballast.
(3) Surface drainage should be directed away from geotextile material to help prevent contamination.
(4) The minimum overlap distance in the longitudinal and transverse directions should be 3 ft.
c. Drainage.
(1) Drainage and other earthwork near the track should be completed before final subgrade
preparation begins; this minimizes the likelihood of disturbing the final subgrade surface or getting soil in
the ballast, and also provides a properly draining work site.
(2) Subdrainage installations should be checked before being covered and ditch elevations and
sections checked before track work begins.
5. TRACK CONSTRUCTION.
a. Sub-ballast Placement.
(1) On new construction, the subgrade surface should be inspected before geotextile or sub-ballast is
placed.
(2) Sub-ballast is placed on the prepared subgrade and compacted to provide a working surface for
track construction. Sub-ballast should be placed to the lines of grade shown on the project plans and
compacted to 95 percent of ASTM D 1557 laboratory maximum dry density.
b. Track Construction Sequence. Typical track construction sequence is as follows:
(1) Place ties on the sub-ballast at the required spacing.
(2) Place tie plates on the ties.
(3) Place the line rail on the tie plates and spike in place.
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