Phase II Development of a Short-Radius Guardrail for Intersecting Roadways
Bob Bielenberg, Ronald Faller, Jim Holloway, John Reid, 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 transition while the other attached to a TL-2 end terminal. A series of four full-scale crash tests were conducted on the short-radius guardrail system. The first two tests were conducted according to NCHRP Report No. 350 Test Designation 3-33. Test nos. SR-1 and SR-2 consisted of target impact conditions of a 2,000-kg pickup truck impacting the center of the nose of the short-radius at a speed of 100 km/hr and at an angle of 15 degrees. Test nos. SR-1 and SR-2 were judged unacceptable according to NCHRP Report No. 350 criteria due to rollover of the test vehicle. The third and fourth tests on the short-radius system were conducted as a modified version of NCHRP Report No. 350 Test Designation 3-31. As such, both impacts were 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-3, a 2,036-kg pickup truck impacted the short-radius aligned with post no. 1P at an speed of 102.9 km/hr and at an angle of 0.9 degrees. Test SR-3 was judged unacceptable due to rollover of the test vehicle. Prior to running test SR-4, the short-radius was modified by adding a parabolic flare to the primary side of the system, raising the system height 51 mm, and increasing the capacity of the nose cable plates. In test SR-4, the 2,005-kg pickup truck impacted the short-radius guardrail at a speed of 106.3 km/hr and at an angle of 1.8 degrees. This test was judged unacceptable according to NCHRP Report No. 350 criteria due to intrusion of thrie beam into the wheel well of the pickup truck, rapid deceleration, and significant penetration into the interior occupant compartment. After review of the four full-scale tests, it was evident that the short-radius guardrail system showed potential 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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