Bridge Railing Design Requirements (2024)
Chapter: 7 Conclusions and Suggested Research
CHAPTER 7
Conclusions and Suggested Research
Conclusions
The preceding chapters described the efforts to rewrite an improved AASHTO LRFD BDS Section 13 that incorporates MASH Test Level criteria, along with examples comparing and contrasting the railing designs resulting from the use of the proposed Section 13 and current Section 13. The results indicate only modest changes to railing designs, supporting the general observation that in-service railings designed to earlier editions of AASHTO LRFD BDS are performing acceptably.
A comprehensive literature review was conducted. Synthesis of this literature review resulted in recommended changes to railing geometry, impact loading, material properties for use in design, and analysis and design provisions for concrete barrier railings. Examples were prepared using the proposed design provisions and current Section 13 design provisions. Results indicate modest differences between the two sets of design provisions.
Implementation Plan
A ballot item was developed to be reviewed and presented by the Bridge Components technical committee for adoption of the guidelines as an official AASHTO document. Given the timing of the project, the ballot item will be progressed after the completion date of this project, NCHRP Project 22-41.
Due to the possible impact on railing policies of individual states, a webinar for AASHTO members is suggested that would cover the research findings and provide an in-depth look at the new Section 13—where it differs from the current version and new content—and present example railing and deck overhang designs when using the proposed specifications.
An additional method to facilitate implementation could be web-based frequently asked questions available to AASHTO members and bridge design and roadside safety design communities.
Future Research
The literature review identified a number of knowledge gaps warranting future research. A partial topic list includes static equivalent impact loads for design, effects of mass activation, design requirements for ground-mounted railing supports, GFRP-reinforced bridge decks, alternate railing design methodologies, and protection or shielding for superstructure elements behind and extending above traffic railings.
