TrinityHighway.com
13
Created November 2021
Site Preparation
The SRT™ 31 System is a straight flared, single-sided, re-directive, and gating end terminal. It may be
specified for use by the state/specifying agency in conjunction with strong post W-beam guardrail systems
on the roadside or median of a roadway. The decision to specify the SRT™ 31 System for a particular
project is the responsibility of the state/specifying agency design engineer who must ensure that the most
appropriate end terminal has been selected for the specific site conditions.
The SRT™ 31 System is designed to be attached to strong post W-beam guardrail systems that have been
accepted under NCHRP Report 350 crash test criteria that use either no offset blocks, 8” [203 mm] offset blocks
or 12” [305 mm] offset blocks.
I
mportant: The SRT™ 31 System must not be attached directly to a weak post W-beam
guardrail system without an approved weak-post-to-strong-post transition plus a
minimum of 12’-6” [3.81 m] strong post W-beam guardrail with 6’-3” [1.91 m] post
spacing. The 12’-6” [3.81 m] strong post W-beam guardrail must be placed between the
SRT™ 31 System and the weak-post- to-strong-post transition.
Important: The SRT™ 31 System must not be attached directly to Thrie Beam, Thrie
Beam Transition, or to a post which is stronger/stiffer than a standard W-beam W6x8.5#
[W150x13] or W6x9# [W150x13.5] guardrail post. A minimum of 6’-3” [1.91 m] strong
post single ply W-beam guardrail must be placed between the SRT™ 31 System and the
Thrie Beam transition (or stronger/stiffer post).
Important: Do not attach the SRT™ 31 System directly to a rigid barrier (i.e. concrete
barrier, wall or bridge pier) without the use of a state/specifying agency approved
transition.
Important: Ensure that the SRT™ 31 System application conforms to the AASHTO
Roadside Design Guide
.
Important:
Trinity Highway does not direct grading. Proper site grading must be
accomplished before assembly of the SRT-31 System in accordance with local
guidelines OR the AASHTO Roadside Design Guide (see Appendix A), whichever is
more stringent. Failure to follow this warning could result in serious injury or death in
the event of a vehicle impact with the system.
Important: The Beginning Length of Need (“BLON”) for the SRT™ 31 System was
established during NCHRP Report 350 Test 3-35 at Post #3, which is 12’-6” [3.81 m] from
the center of Post #1.
Important:
A minimum of 75’ [22.86 m] of strong post W-beam guardrail with 6’-3”
[1.90 5m] post spacing must be placed between two SRT™ 31 Systems when installed
with both an approach and departing end on NCHRP Report 350 TL-3 roadway
applications. For roadway applications that meet the NCHRP Report 350 Test Level 2
(TL-2) or Test Level 1 (TL-1) criteria, the SRT™31 TL-3System can be placed “end to
end”, if specified and approved by the state/specifying agency. The minimum installation
length for TL-2 and TL-1 applications is 81'-3" [24.77 m] long consisting of two (2) 40’-7
1/2” Systems or two (2) 34’-4 1/2” Systems plus one (1) 31” high, 12’-6” strong post single
ply 12 gauge W-beam guardrail system.
