Tie-downs and transitions for temporary concrete barriers

Temporary concrete barriers are one of the most common types of roadside hardware found on the nation's highways. However, unresolved issues exist for some installations. These issues include the need for a tie-down system for barrier installations placed on asphalt roadway surfaces and an approach transition between temporary concrete barriers and rigid barriers. The objective of this research was to design a tie-down temporary barrier for use on asphalt road surfaces and then apply that tie-down system to the design of an approach transition from freestanding to rigid barriers. The tie-down and transition systems were to be evaluated according to Test Level 3 safety performance criteria set forth in NCHRP Report No. 350. For the asphalt tie-down system, three steel pins were installed in holes on the front face of the barrier. The new tie-down design was crash tested according to NCHRP Report No. 350 Test Designation 3-11. The test was judged acceptable, barrier deflections were reduced, and all barriers in the system were safely restrained. The approach transition to rigid barrier was developed through strategic application of the previously designed asphalt tie-downs. Computer simulation with LS-DYNA was used to locate the critical impact point for the full-scale crash test. The system was tested according to NCHRP Report No. 350 Test Designation 3-21. Results show that the vehicle was safely redirected, and the test was judged acceptable. Recommendations concerning the application of both the tie-down and transition designs are given.