Design Requirements for Safer Highway Bridge Rails

Recent accident information obtained during 1965-1968 indicates that: (1) approximately 22% of the fixed object freeway fatal accidents involve bridge railing systems, and (2) certain areas of a bridge railing system if not properly designed, or adequately protected, or both can constitute a hazardous condition to an out-of-control vehicle. In order to evaluate the performance of a bridge railing system, a simple mathematical model simulating a standard size vehicle striking a railing has been developed and verified. This model takes into consideration vehicle parameters as well as roadway characteristics. Employing the model and extending the work of the National Safety Council, a first approximation has been made to estimate decelerations or impact forces. Based on the experience and judgment of highway engineers, available research, and the results of this study, a Tentative List of Bridge Railing Service Requirements has been defined to help the highway engineer appraise or design any bridge railing system.