March 30, 2004 

Refer to: HSA-10/B-126 

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

Research Assistant Professor 

Midwest Roadside Safety Facility-UNL 

527 Nebraska Hall 

Lincoln, Nebraska 68588-0529

Dear Dr. Faller: 

In your February 24, 2004 letter to Mr. A. George Ostensen, you provided information on the 

design and crash testing recently done on Nebraska Department of Roads’ Open Concrete Bridge 

Rail and requested formal acceptance of this design for use on National Highway System (NHS). 

This bridge rail is a concrete post and beam design. Support posts are 11-inches wide and 

24-inches long, spaced on 8-foot centers. The reinforced concrete beam is 16-inches high, 

14-inches deep and has a top height of 29 inches. The clear distance beneath the beam is 

13 inches. The offset from the traffic face of the beam to the face of each post is 2 inches. 

Staff review of your request and its supporting documentation revealed that this bridge railing 

has been previously accepted as a National Cooperative Highway Research Program (NCHRP) 

Report 350 test level 4 (TL-4) bridge railing and is listed on the Federal Highway 

Administration’s safety hardware website under the Bridge Railing category (Appendix B7, page 

14 of 15 under the sub-heading Vertical Concrete Parapet – Open or Closed/General). This 

earlier acceptance was based on test and evaluation criteria contained in NCHRP Report 230 

and in the 1989 AASHTO Guide Specifications for Bridge Railings, and the railing was assigned 

an NCHRP Report 350 “equivalency” test level 4 (TL-4). The test documented in your January 

21, 2004 report entitled “Safety Performance Evaluation of the Nebraska Open Bridge Rail on an 

Inverted Tee Bridge Deck” verified acceptable impact performance with the NCHRP Report 350 

2000P truck impacting at a nominal speed of 100 km/h and a 25-degree impact angle. Enclosure 

1 is the test summary page from that report. Although the bridge rail itself was identical to the 

previously tested rail, the bridge deck design and rail attachment details differed from the 

original tests in which the concrete post and beam bridge rail was constructed on a 

200-mm thick deck with the vertical steel tied to two layers of deck reinforcing. For the latest 

test, the rail was constructed on a 150-mm thick inverted Tee section with only one layer of 

reinforcing steel. A cross section of this design is shown in Enclosure 2. 

Based on the results of your recent test, the NDOR Open Concrete Bridge Rail is reconfirmed as 

a TL-4 design and may be used on the NHS (with either deck design) when such use is 

acceptable to the contracting authority. Although your test was successful, damage done to the 
2

wheel and front suspension of the pickup truck and scrub marks on the support post in the impact 

area indicate a potential snagging problem. The Texas T202 bridge rail, a similar concrete post 

and beam design with a 2-inch lower height, a 2-inch shallower beam, and a 1.5-inch offset from 

the beam face to the post face was tested unsuccessfully at the Texas Transportation Institute. 

When the offset dimension was increased to 4.5 inches, acceptable crash performance resulted. 

To reduce the potential for wheel snagging, you may wish to consider increasing the rail-to-post 

offset dimension in the NDOR design and/or using trapezoidal-shaped rather than rectangular 

posts to offset the leading edges of these posts further away from traffic. 

Sincerely yours, 

 

 /Original Signed By R. Powers/ 

for: 

John R. Baxter, P.E. 

 Director, Office of Safety Design 

 Office of Safety 

2 Enclosures 
42

0.079 sec 0.126 sec 0.221 sec 0.308 sec 0.000 sec

! Test Number . . . . . . . . . . . . . . . NIT-1! Date . . . . . . . . . . . . . . . . . . . . . 3/20/02! Appurtenance . . . . . . . . . . . . . . Nebraska’s Open Concrete Bridge Rail Attached

to an Inverted Tee Bridge Deck System

! Total Length . . . . . . . . . . . . . . . 31.95 m! Concrete Material . . . . . . . . . . . Nebraska 47-BD Mix! Reinforcing Steel Material . . . . Grade 60 Rebar - Epoxy Coated! Concrete Bridge Rail

Length . . . . . . . . . . . . . . . . 29.57 mWidth . . . . . . . . . . . . . . . . 356 mmDepth . . . . . . . . . . . . . . . . 406 mmTop Mounting Height . . . . 737 mm

! Concrete Bridge Posts

Length . . . . . . . . . . . . . . . . 610 mmWidth . . . . . . . . . . . . . . . . 279 mmHeight . . . . . . . . . . . . . . . . 330 mmSpacing . . . . . . . . . . . . . . . 2,438 mm

! Concrete Bridge Deck

Length . . . . . . . . . . . . . . . . 31.95 mWidth . . . . . . . . . . . . . . . . 1,829 mmThickness . . . . . . . . . . . . . 152 mm

! Vehicle Model . . . . . . . . . . . . . 1995 GMC 2500 3⁄4-ton pickup

Curb . . . . . . . . . . . . . . . . . 1,963 kgTest Inertial . . . . . . . . . . . . 2,016 kgGross Static . . . . . . . . . . . . 2,016 kg

! Vehicle Speed

Impact . . . . . . . . . . . . . . . . . . . 99.8 km/hrExit . . . . . . . . . . . . . . . . . . . . . . 80.0 km/hr

! Vehicle Angle

Impact . . . . . . . . . . . . . . . . . . . 26.6 degExit . . . . . . . . . . . . . . . . . . . . . . est. 13-15 deg

! Vehicle Snagging . . . . . . . . . . . . . . . None ! Vehicle Pocketing . . . . . . . . . . . . . . . None! Vehicle Stability . . . . . . . . . . . . . . . . Satisfactory! Occupant Ridedown Deceleration (10 msec avg.)

Longitudinal . . . . . . . . . . . . . . . 6.29 G’s < 20 G’sLateral (not required) . . . . . . . . 7.75 G’s

! Occupant Impact Velocity

Longitudinal . . . . . . . . . . . . . . . 6.60 m/s < 12 m/sLateral (not required) . . . . . . . . 7.75 m/s

! Vehicle Damage . . . . . . . . . . . . . . . . Moderate

TAD9 . . . . . . . . . . . . . . . . . . . . 1-RFQ-4

SAE10 . . . . . . . . . . . . . . . . . . . . 1-RFEW4

! Vehicle Stopping Distance . . . . . . . . 48.16 m downstream

1.52 m laterally behind

! Barrier Damage . . . . . . . . . . . . . . . . . Moderate! Maximum Rail Deflections

Permanent Set . . . . . . . . . . . . . NADynamic . . . . . . . . . . . . . . . . . . 22 mm

! Working Width . . . . . . . . . . . . . . . . . 587 mm

Figure 20. Summary of Test Results and Sequential Photographs, Test NIT-1