What are Tennessee Bridge Mounted Interconnection Portable Barrier Specifications?

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The Tennessee Department of Transportation outlines specifications regarding the proper dimensions for concrete barriers, including general notes, section details, and more.

Tennessee Bridge Mounted Interconnection Portable Barrier General Notes

The Tennessee Department of Transportation’s general instructions are as follows:

  1. Precast concrete barriers should be constructed with Class A concrete manufactured in accordance with Section 604 of the Standard Specifications.

  2. Reinforcing steel should be ASTM A615.

  3. The connector pin should be a 1-1/4” x 25-1/8” F1554 Grade 36 anchor bolt or 1-1/4” x 25-1/8” A307 Grade A bolt. The connector pin, top connector, bottom connector, nuts and washers should be galvanized in accordance with AASHTO M-111. This standard depicts the traditional pin and eye connection details. Any Federal Highway Administration approved, NCHRP 350 compliant connection, such as the J-J hook positive connection, may also be used.

  4. Place all steel reinforcement 2” minimum from the outside face of the barrier, except as otherwise shown.

  5. Payment will be made under item number designated on the plans for bridge mounted interconnected portable barrier rail (per linear foot).

  6. Any salvable value of the portable barrier rail will become the property of the contractor. The portable barrier rail should be moved off the project in a manner and time suitable to the engineer.

  7. When interconnected portable barrier rail is fabricated in the upright position as shown on this drawing, the VB400 lifting bar will become optional and may be omitted from the installation.

  8. This barrier has been successfully tested to the requirements of NCHRP 350. The contractor may submit alternate barriers that have been approved by the Federal Highway Administration as NCHRP 350 compliant. The alternate barriers must be certified by the contractor as having been fabricated in accordance with the approved alternate details.

Different section lengths and different approved connections can be used on a specific project (refer to general notes H and C above). Only one section length and connection type should be used in a single run of interconnected portable barrier rail.

  1. Transverse slots in bottom of rail should be plugged where required to prevent drainage from impinging on traffic lanes, railroad right of way, or as directed by plans.

  2. Immediately after removal of barrier rail, the holes in the bridge deck for the anchor bolts should be cleaned and packed with non-shrink grout. All grouting material should be on the materials and test qualified products list (QLP).

Tennessee Bridge Mounted Interconnection Portable Barrier Specifications

Tennessee barriers should conform to the following specifications, according to the Tennessee Department of Transportation.

Plan View

Barriers include ¾” diameter concrete anchors for mounting vertical panels. Their corners form to a ½” bevel or radius. They measure 2’-3” wide. The distance between the edge of the barrier and the farthest end of the loop bar is 2-1/2” maximum (typical).

Barriers include anchor bolt holes that are 2” in diameter. The first anchor bolt hole is spaced 2’-0” from the left end of the barrier; spacing after that depends on the length of the barrier:

  • 2 SPA. @ 4’-3” = 8’-6” (12’-6” Section)

  • 4 SPA. @ 4’-3” = 16’-0” (20’-0” Section)

Elevation View
Each barrier is 20’-0” long and includes two 6” lifting slots, which are set 3’-4” when measured from the center of the slot to the nearest outer edge of the barrier.

On the left side of the barrier, the bottom connector is spaced 6” from the ground level and the upper connector is spaced 6” from the top of the barrier. On the left side of the barrier, the bottom connector is spaced 8” from the ground level and the top connector is spaced 8” from the top of the barrier.

Each barrier includes one bar A600, two bars A601, bars A400, bar VB400, bar X600, four bars C400 (on each side), and bars U400.

  • Bar C400 is an L-shaped bar that measures 2’-4” (long end) and 4” (short end)

  • Bar U400 is a U-shaped bar that measures 2’-4-1/2” tall, 1’-8” wide (large end) and 5-1/2” wide (short end)

  • Bar VB400 is a V-shaped bar that measures 10” long on each side and a total of 9” wide for the entire bar

  • Bar X600 is a U-shaped bar that measures 1’-11” (longways) and has a total width of 8”

Lifting Hole and Slot Notes

Two 2” diameter lifting holes are required for each section to be placed 3’-4” from either end of the barrier rail. Additional holes may be added to 20’-0” section lengths. Placement of additional holes to be at the discretion of the fabricator, formed with 2” PVC pipe or equal.

Lifting bars are required to prevent spalling of concrete around holes.

End Elevation

Barriers measure 2’-3” wide on the bottom, 9” wide at the top and stand 2’-8” tall. They include ½” bevel or radius at their top edges and a 10” radius at the break point.

Clearance Notes

If 4’-0” of clearance from the toe on the backside of a barrier to the edge of the slab is available then no anchor bolts will be required.

Connector Pin

Connector pins measure 2’-1-1/8” long and include a 1-1/2” threaded end that is fitted with a 1-1/4” heavy hex nut plus a steel washer (F436 typ.). Connector pins are 1-1/4” diameter steel bar F1554 Grade 36.

Bottom Connector

Bottom connectors should be galvanized after forming. They are made of ¾” diameter steel bar ASTM A36 and include a 7/8” radius on the closed side. The open side measures a total of 9-1/4” wide.

This blog post is an interpretation of specifications by the Tennessee Department of Transportation. Please consult with Tennessee DOT's most recent requirements for definitive information.

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