Computational and experimental modification of portable sign structure design following NCHRP 350 criteria

As a follow-up to a study published in 2008 [J.-W. Seo, D.G. Linzell, and Z. Rado, Crash performance of x-shaped support base work zone temporary sign structures, Int. J. Crashworthiness 13 (2008), pp. 437-450], research discussed herein examines effective methods for selecting and modifying portable sign structure designs so that they are deemed acceptable according to National Cooperative Highway Research Program (NCHRP) Report 350 [H.E. Ross, Jr., D.L. Sicking, J.D. Zimmer, and R.A. Michle, Recommended procedures for the safety performance evaluation of highway features, National Cooperative Highway Research Program Rep. 350, Publication Project 22-7 FY'89, Texas Transportation Institute, Austin, TX, 1993] criteria. Portable sign structures, often used as signage for work zones, are frequently susceptible to vehicular impact. If an impact occurs, a possible safety threat to occupants in the vehicle exists due to sign panel penetration. In this study, the methodology used to select a portable sign structure design from two alternatives, one of which was summarised in the 2008 publication [J.-W. Seo, D.G. Linzell, and Z. Rado, Crash performance of x-shaped support base work zone temporary sign structures, Int. J. Crashworthiness 13 (2008), pp. 437-450], is presented along with the procedure used to optimise the selected design so that it performed acceptably according to the NCHRP 350 standards. The selected design, one having an H-base, was modified to meet the NCHRP 350 criteria by strategically replacing traditional metallic fasteners with nylon fasteners. Procedures used to simulate the impact tests, select the appropriate base design and modify that design to meet the NCHRP criteria are presented.