What are Texas Single Slope Concrete Barrier (Precast) X-Bolt Connection, Unrestrained, Mash TL-4 Specifications?

The Texas Department of Transportation outlines specifications regarding the dimensions of single slope concrete barriers (precast, X-bolt connection, unrestrained, MASH TL-4), including elevation view notes, plan view details, section details, and more.

Texas Single Slope Concrete Barrier (Precast) X-Bolt Connection, Restrained, Mash TL-4 Notes

General Notes

This barrier system has been successfully evaluated by full-scale crash tests to meet MASH TL-4 criteria. This barrier system had approximately 33” of dynamic or permanent deflection as it contains and redirects the TL-4 (single-unit truck) errant vehicle. This barrier system is designed to have approximately 15 inches of dynamic or permanent deflection as it contains and redirects the TL-3 (pickup truck) errant vehicle.

The average weight of one 30 foot precast barrier is 19,960 pounds.

The average weight of one precast barrier is 665 plf.

Cover dimensions stated in the Texas Department of Transportation’s specifications are clear dimensions unless otherwise noted. Reinforcing bar dimensions shown on the plans are out-to-out of the bar.

Material Notes

All metal components of the barrier system should be galvanized.
Provide Class “S” concrete (f’c = 4,000 psi) in general, but provide Class “S” (HPC) if it’s required elsewhere.
All reinforcing steel and WWR should be galvanized if required or shown elsewhere.
Provide Grade 60 reinforcing steel.
Provide deformed welded wire reinforcements (WWR) (ASTM A1064).
Provided welded wire reinforcements (WWR) laps, where required, which should be either uncoated or galvanized ~ D22.2 = 1’-7”.

Construction Notes

Lifting devices (such as lugs, loops, etc.) should be provided at the Contractor’s or Engineer’s direction. Locate lifting devices in the rail so as not to exceed the tensile strength of the concrete during lifting. Galvanize all permanent steel lifting components.

All exposed corners should be chamfered.

Texas Single Slope Concrete Barrier (Precast) X-Bolt Connection, Restrained, Mash TL-4 Specifications

Elevation View
Barriers measure 30’-0” long and include a 1” end cover (typ.) on both ends. Barriers also include two leave-out blocks on each side (for a total of four blocks per panel). Within the barrier is a WWR cage (A), WWR cage B, U1 (#4) bars, and U2 (#4) bars.

The WWR cage (A) includes 21 bars spaced 1’-2” apart for a total of 24’-6” of cage length. The WWR cage (B) includes 21 bars spaced 1’-4” apart for a total of 28” of cage length.

Barriers include an expansion joint that measures 12” (minimum), and are set over a bridge slab or continuously reinforced concrete pavement (CRCP) that is at least 7” thick.

Plan View

Barrier plan views show an X-bolt connection made of PVC pipe that is 1-1/2” in circumference (Sch 40). The bolts are angled at 70 degrees (typ.), and the adjacent precast barrier segments are connected at their symmetrical center with a joint connection.

The distance between the end of the leave out block and the joint connection on the left side is 11-1/8”. The distance between the end of the leave out block and the joint connection on the right side is 1’-3-7/8”.

View A-A

Barriers stand 3’-6” tall and measure 8” wide at the top and 24” wide at the bottom. They include a ¾” chamfer (typ.) on all corners. The barrier slope is 8” wide (on each side). Barriers are symmetrical down the center line. There is a minimum distance of 1-1/2” (typ). between all interior reinforcing bars and the outside edge of the barrier.

It should be noted that threaded rods with nuts and washers for X-bolt connections are not included in view A-A for clarity.

Top and Bottom Threaded Rod Assembly Details

Top threaded rods measure 2’-8” long and are 7/8” in diameter. They are fully threaded rods (ASTM A193 Gr B7 or F1554 Gr 105). Top threaded rods include a PL washer that is ½” x 4” x 4” (ASTM A36) with a 1” diameter hole in the center. Washers are 7/8” hardened steel (ASTM F436).

Bottom threaded rods measure 3’-6” long and are 7/8” in diameter. They are fully threaded rods (ASTM A193 Gr B7 or F1554 Gr 105). Bottom threaded rods include a PL washer that is ½” x 4” x 4” (ASTM A361) with a 1” diameter hole in the center. Washers are 7/8” hardened steel (ASTM F436).
Installation of threaded rods must not extend beyond the face of the barrier.

__Leave Out Block Details __

View B-B:

View B-B shows a 1-1/2” PVC sleeve (Sch 40) that is set to the left of the leave-out block. The leave-out block measures 1’-3” long and 5-3/8” tall. The PVC sleeve is centered vertically next to the leave-out block.

Top View:

A top view shows that the PVC sleeve is set on the opposite of the face side of the barrier.

X-Bolt Connection with Forming and Leave-Out Block Placement Details

Leave-out blocks are connected with 1-1/2” PVC pipe (Sch 40). The leave-out block on the left side (the left barrier segment) is set 11-1/8” from the joint connection. The leave-out block on the right side (the right barrier segment) is set 1’-3-7/8” from the joint connection. The left-hand leave-out blocks are spaced 1’-5” from the ground line, and the right-hand leave-out blocks are spaced 2’-2” from the ground line.

Bar Details

Bars U1 (#4) are U-shaped bars that measure 3’-6” long and 11-3/4” wide (from open end to open end).
Bars U2 (#4) are U-shaped bars that measure 3’-6” long and 8-1/4” wide (from open end to open end).

Welded Wire WWR Details

Cage A measures 5’-1/2” wide at the top and 1’-8-1/4” wide at the bottom. It stands 3’-3” tall.

Cage B measure 5-1/4” wide at the top and 7” wide at the bottom. It stands 1’-7” tall.

This blog post is an interpretation of specifications by the Texas Department of Transportation (TxDOT). Please consult with TxDOT' most recent requirements for definitive information.

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