March 14, 2003 

 HSA-10/B112 

Ronald K. Faller, Ph.D., P.E. 

Research Assistant Professor 

Midwest Roadside Safety Facility 

P.O. Box 880601 

Lincoln, NE 68588-0601 

Dear Dr. Faller: 

In your letter dated October 24, 2002, you requested formal Federal Highway 

Administration acceptance of a steel strap “tie-down” system designed to limit the 

deflection of temporary concrete barrier when used on a bridge deck or in other locations 

where the barrier’s normal design deflection would not be tolerable. 

The proposed design was tested using a total of sixteen 3.8-m long sections of the Iowa 

pin and loop F-shape barrier that was formally accepted as an NCHRP Report 350 barrier 

at test level 3 (TL-3) in Mr. Dwight A. Horne’s October 10, 1997 letter (acceptance letter 

B-41). These barriers were set 305 mm from the outside edge of the simulated bridge 

deck. The “tie-down” system consisted of a trapezoidal-shaped 6.4-mm thick A36 steel 

strap at each barrier joint through which the connecting pin between adjacent barrier 

segments is inserted. This strap, shown in the enclosure to this letter, was then attached 

to the concrete bridge deck with two 19-mm diameter x 57-mm long ISO Class 8.8 bolts 

set into 19-mm diameter Red Head drop-in anchors. These anchors were embedded 

81mm into the concrete deck. Eleven tie-down straps were used. The test vehicle 

impacted the barrier 1.2 upstream of the gap between segments 8 and 9. At that point, 

there were four strap anchors upstream of the impact point and seven anchors 

downstream. The first three joints upstream of the impact and the last downstream joint 

were not anchored. Thus, the impact point was approximately 30 m downstream from the 

approach end of the test installation and approximately 14 m downstream from the first 

strap anchor 

As noted in your August 16, 2002 report entitled “Development of a Tie-down System 

for Temporary Concrete Barriers”, the design was successfully tested to NCHRP Report 

350 TL-3. Dynamic deflection of the barrier was 960 mm, with one segment deflected 

over the edge of the bridge deck and the two adjacent segments partially deflected over 

the edge. However, the pin and loop connections and the intact tie-down straps along the 

rest of the barrier segments held the deflected segments in place on the bridge as desired. 

Two tie-down straps in the immediate impact area were pulled out of the deck and three 

adjacent straps showed extensive deformation, as did several of the connecting pins and 

barrier loops. However, none of the barrier pin and loop connections failed. Impacts 

closer to the unanchored segments at either end of the bridge can be expected to result in 

larger lateral barrier deflections. 

Based on staff review and recommendations, I agree that the tested design satisfies 

NCHRP Report 350 evaluation criteria at TL-3 and that this design may be used on the 
National Highway System to limit the deflection of temporary concrete barriers located 

on a concrete surface. 

 Sincerely yours, 

 (original signed by Michael S. Griffith) 

 Michael S. Griffith 

 Acting Director, Office of Safety Design 

 Office of Safety 

Enclosure