Book Description

The use of curbs along roads is often required for certain functions such as drainage control, right-of-way reduction and sidewalk separation. However, curbs along roadways can adversely affect the interaction of errant vehicles with roadside barriers. Curbs placed near guardrail systems increase the propensity for vehicle override, vehicle underride, vehicle instability, and excessive rail loading during impact events. The Midwest Guardrail System (MGS) installed behind curbs was evaluated under National Cooperative Highway Research Program (NCHRP) Report 350 Test Level 3 (TL-3) criteria but has not been evaluated to American Association of State Highway Transportation Officials (AASHTO) Manual for Assessing Safety Hardware (MASH) TL-3. Test nos. MGSC-7 and MGSC-8 were conducted on the MGS offset by 6 in. behind a 6-in. tall AASHTO Type B curb in accordance with MASH 2016 test designation nos. 3-10 and 3-11, respectively. During test no. MGSC-7, the 1100C vehicle impacted the system at 63.6 mph at an angle of 25.0 degrees and was successfully contained and redirected by the system. The system was rebuilt and tested again according to MASH test designation no. 3-11. In test MGSC-8, the 2270P vehicle impacted the system at 63.4 mph at an angle of 25.7 degrees and was successfully contained and redirected by the system. Upon the successful completion of the two full-scale crash tests, the MGS was deemed crashworthy to MASH 2016 TL-3 when placed within 6 in. behind a curb. Installation guidelines were presented to address implementation of the MGS with curb in various barrier configurations as well as in conjunction with a number of roadside features and special applications.