Crash Testing and Analysis of Work-Zone Sign Supports

A variety of traffic-controlling devices are used in work zones; some of these are not normally found on the roadside or in the traveled way outside of the work zones. These devices are used to enhance the safety of the work zones by controlling the traffic through these areas. Because of the placement of the traffic control devices, the devices themselves may be potentially hazardous to both workers and errant vehicles. The impact performance of many work-zone traffic control devices is mainly unknown, and to date limited crash testing has been conducted under the criteria of NCHRP Report 350: Recommended Procedures for the Safety Performance Evaluation of Highway Features. The results of full-scale crash testing of flexible panel work-zone sign stands were evaluated and analyzed to quantify the features that successful devices shared, as well as common features of those devices that failed salient safety criteria. Parameters considered included sign base and upright properties, sign height, cross-member properties, and ancillary details. Results pointed to three problematic, fundamental design issues: (a) combinations of base and upright stiffness and strength that generally lead to significant windshield damage, (b) cross members that lead to windshield damage in the end-on (90°) impact orientation, and (c) appurtenances that have an impact on performance. Although there are a significant number of variables that control the performance of a given device, these generalizations offer a basis for the evaluation of the fundamental design elements.