Multiple-service-level highway bridge railing selection procedures.

This report contains the findings of an extensive analytical and experimental investigation intended to advance procedures for development of bridge railing systems. A lower cost ($10/linear ft. installed) bridge railing system, intended for use when warranted by particular site conditions, was developed and evaluated by full-scale crash tests. Furthermore, an approach was developed for selecting the appropriate category of railing system based on a classification of conditions at the particular bridge site. These findings are recommended for immediate application and will be of interest to bridge engineers and others concerned with design and performance of bridge railings and vehicle barrier systems in general. Procedures that permit the rapid service level selection for a bridge site based on functional classification and traffic volume is presented. The multiple-service-level approach (MSLA) of this project is formulated from consideration of frequency and severity of bridge railing collisions. By comparing the benefits of bridge railing with the cost of bridge railing, benefit and cost (B/C) ratios are determined for typical bridge sites. Determination of service level is readily achieved by using these B/C ratios as a basis. An in-depth investigation of all aspects of bridge railing technology was conducted. Findings include the recommendation for performance testing of bridge railings. Static load or force criteria for bridge railings are not recommended. Current bridge railings are assessed for service level designation and estimated installed cost. The current AASHTO bridge railing specification is discussed and recommendations made for revision and additions. Guidelines are presented that will aid a user agency in applying the MSLA procedures to existing construction. Use of these guidelines will enable the agency to develop a priority procedure for upgrading bridge railings with demonstrated inadequate capacity. Traffic volume at a bridge site was identified as generally the most important variable with regard to service level designation.