Development of a Flexible Bridge Railing for Longitudinal Timber Decks
REPORT NUMBER
TRP-03-062-96
AUTHORS
Ronald Faller, Barry Rosson
PUBLICATION DATE
1997-06-01
ABSTRACT
A low-cost, flexible W-beam bridge railing with "breakaway" posts was developed for use on longitudinal timber deck bridges located on low-volume roads. The bridge rail consisted of a 12-gauge (2.66-mm) W-beam rail supported by 3.5-in. by 5.5-in. (89-mm by 140-mm) dressed lumber posts spaced 6-ft 3-in. (1,905-mm) on center. Each post was placed between two 5-in. by 5-in. x 3/8-in. (127-mm x 127-mm x 9.5-mm) steel angles and connected to the vertical edge of the bridge deck with two 3/4-in. (19.0-mm) diameter by 12.0-in. (305-mm) long lag screws.
The research study included 37 static component tests, computer simulation modeling with BARRIER VII, and two full-scale vehicle crash tests using 3/4-ton pickup trucks. The first crash test, impacting at a speed of 31.2 mph (50.2 km/hr) and at an angle of 26.8 degrees, was unsuccessful because the vehicle vaulted over the bridge rail using a 24-in. (610-mm) top mounting height. Consequently, the height of the railing was increased to 27.78 in. (706 mm), resulting in a successful crash test at a speed of 30.6 mph (49.2 km/hr) and at an angle of 24.9 degrees. The safety performance of the bridge railing was determined to be acceptable according to the Test Level 1 (TL-1) evaluation criteria described in the National Cooperative Highway Research Report No. 350, Recommended Procedures for the Safety Performance Evaluation of Highway Features.
The research study included 37 static component tests, computer simulation modeling with BARRIER VII, and two full-scale vehicle crash tests using 3/4-ton pickup trucks. The first crash test, impacting at a speed of 31.2 mph (50.2 km/hr) and at an angle of 26.8 degrees, was unsuccessful because the vehicle vaulted over the bridge rail using a 24-in. (610-mm) top mounting height. Consequently, the height of the railing was increased to 27.78 in. (706 mm), resulting in a successful crash test at a speed of 30.6 mph (49.2 km/hr) and at an angle of 24.9 degrees. The safety performance of the bridge railing was determined to be acceptable according to the Test Level 1 (TL-1) evaluation criteria described in the National Cooperative Highway Research Report No. 350, Recommended Procedures for the Safety Performance Evaluation of Highway Features.
KEYWORDS
Highway Safety, Roadside Safety, Guardrail, W-beam, Longitudinal Timber Deck, Bridge Railing, NCHRP-350, Low-volume, Computer simulation, Crash test, TL-1
Other files to download
DRAWINGS