1 MARCH 2000
Figure 6-19. Geotextile Installation at a Bridge Abutment
b. Material and Installation Specifications. Geotextiles, and their installation, will conform with the
specifications in chapter 1, part 10 of the AREMA Manual.
c. Design Guidance. TM 5-818-8 will be used for the design of geotextile applications.
d. Drainage Applications. Lighter weight geotextiles are often useful for drainage applications outside of
the track structure, especially in subdrainage.
a. Purpose. Ballast performs four primary functions:
(1) Distributes wheel loads at reduced pressure to the subgrade.
(2) Restrains the track laterally and longitudinally.
(3) Helps maintain track surface.
(4) Allows track structure to drain.
b. Material Type.
(1) As ballast depends on high friction and interlock to be effective in restraining track and must also
withstand large loads, ballast must consist of a hard angular crushed rock or crushed slag.