TrinityHighway.com
14
Revision A November 2021
Ground Preparation and Barrier Alignment
CASS
®
shall be placed on a median or roadside without obstructions, depressions, etc. that may
significantly affect the stability of an errant vehicle. Grading of the site and/or appropriate fill
materials may be required. The assembler shall “flatten” or “round” various topographical
inconsistencies that could interfere with the ability to consistently maintain the design height (in
relation to the terrain) of the cables. To address assembly in rock, see Appendix C: Encountering
Rock.
Warning:
It is imperative, before assembly, that you contact a Trinity Highway
representative and state/specifying agency engineer for special criteria involving
soil conditions not meeting or exceeding NCHRP Report 350 soil conditions. It is
also recommended that you consult your own soils or structural engineer.
Note:
Based on soil conditions at the site, ANY or ALL foundations may need larger/deeper
concrete footings or larger soil plates (for driven applications.) as determined by soil analysis.
Ground Preparation
When CASS
®
is placed in a median, use the following criteria for locating the system:
Ensure that the finished grade (side slope) is 1V:6H or flatter.
FHWA and AASHTO guidance for ANY NCHRP-350 cable system placed on
side slopes steeper than 1V:10H shall not be placed within 1’ to 8’ [0.3m to
2.4m] from the ditch line.
Barrier Alignment
Follow all procedures in the placement of the footing and/or post to ensure proper alignment. It
is suggested that a string line or other means be used to provide a consistent horizontal and
vertical alignment that meets specifications. If assembled on a horizontal curve, a minimum 650
foot [198 m] radius is required. If assembled on a sag vertical curve, the K value is ≥ 100’ [30 m].
See “Assembly on a Curve” Section.
CASS
®
can be placed on the roadside in front of slopes 1V:2H or flatter. Use a minimum distance
of 2’ [0.6 m] in front of the hinge point to the center of the post.
Use the appropriate state/specifying agency’s guardrail terminal standards for grading and
widening for the CCT.
There may be instances where a break will be required in the cable run. In these circumstances
proper overlap of the terminals is required in order to prevent a vehicle from passing through the
protected area. Depending on the location of the cable with respect to the direction of traffic, there
are two situations which can occur. See Appendix B for recommended overlaps.
Important:
A flare rate of 30:1 or flatter is required if the barrier must be flared,
transverse across the median, or if CASS
®
must have a change in
direction (See Appendix A).
