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Phase III Development of a Short-Radius Guardrail for Intersecting Roadways




Cody Stolle, Karla Lechtenberg (Polivka), Bob Bielenberg, John Reid, Ronald Faller, John Rohde, Dean Sicking




This research study consisted of the development and testing of a short-radius guardrail system for protection of hazards near intersecting roadways and capable of meeting the Test Level 3 (TL-3) impact conditions of the NCHRP Report No. 350 criteria. A short-radius system was designed and consisted of a curved and slotted thrie beam nose section with two adjacent slotted thrie beam sections supported by breakaway posts. One side of the system was attached to a TL-3 steel post approach transition while the other attached to a TL-2 end terminal. A series of two full-scale crash tests were conducted on the short-radius guardrail system. The first test on the short-radius system was conducted as a modified version of NCHRP Report No. 350 Test Designation 3-31. As such, the impact was oriented at an angle of 0 degrees to the roadway, but the impact point was altered to force the vehicle to move directly down the primary side of the system. This was believed to be a more critical impact condition than provided by the standard test 3-31. In test SR-5, a 2,001-kg (4,412-lb) pickup truck impacted the short-radius with its center aligned with post no. 1P at an speed of 101.8 km/h (63.2 mph) and at an angle of -0.3 degrees. The pickup truck was safety redirected, and test SR-5 was judged acceptable according to NCHRP Report No. 350. The second test on the short-radius system was conducted according to NCHRP Report No. 350 Test Designation 3-30. Prior to running test SR-6, the short-radius was modified by altering the upstream anchor for the primary side. Bogie testing was conducted on the modified anchor to insure that the design generated appropriate anchor loads. In test SR-6, an 893-kg (1,969-lb) small car impacted the short-radius guardrail at a speed of 99.4 km/h (61.8 mph) and at an angle of 0.8 degrees on the center of the curved nose of the system. This test was judged unacceptable according to NCHRP Report No. 350 criteria due to excessive ridedown decelerations. After review of the full-scale tests, it was evident that the short-radius guardrail system showed significant improvement over the original system developed by the Midwest Roadside Safety Facility, but further development was required.


Highway Safety, Guardrail Longitudinal Barrier, Short-Radius Barrier, Intersection Protection, Roadside Appurtenances, Crash Test, Compliance Test

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