The American Association of State Highway and Transportation Officials (AASHTO) has been setting standards and publishing specifications, test protocols and guidelines for highway design and construction since 1914. Until recently, these standards focused on conventional materials. In June 2024, state Department of Transportation (DOT) engineers approved the Load and Resistance Factor Design (LRFD) Guide Specifications For The Design Of Fiber Reinforced Polymer (FRP) Pedestrian Bridges. The new guidelines represent a major step forward in FRP pedestrian bridge design specifications.
Origin Story
AASHTO first published guidelines for FRP truss bridges in 2008 after the superstructure became the industry’s most established bridge structure using Fiber Reinforced Polymer (FRP) composite material. FRP’s versatility added length [25 ft. to 100 ft.] to the structure while making it possible to build and install composite bridges anywhere. The material’s high strength and deflection characteristics also allowed the bridge to accommodate pedestrians, bicyclists, equines and lightweight vehicles. As market interest in the technology grew, Creative Composites Group (CCG) began to develop and add innovative bridge products. In 2022, new leadership on AASHTO T-6’s technical committee prompted meetings with the American Composites Manufacturers Association (ACMA) to update the guidelines with best practices for the new products.
Growing Line-Up
Guidelines were updated for pultruded truss-style bridges and the connections for these structures. New guidelines were created for pultruded decking and sandwich construction molded decking as well as non-slip overlays, joints and drainage details. New information for inspection guidelines was also added. Other input includes deflection and vibration updates and the addition of a section on aesthetics.
Milestone
LRFD Guide Specifications For The Design Of Fiber Reinforced Polymer (FRP) Pedestrian Bridges gives owners and agencies the roadmap they need to include FRP structures in their projects. Ongoing education has helped the industry understand that FRP is no longer the new kid on the block. The new guide emphasizes delegated design since manufacturers will be responsible for designing FRP pedestrian bridges to meet the unique performance requirements specified by the owner. Manufacturers will also be responsible for the design and detailing of connections to the bridge’s superstructure. With the volume [and different types] of bridge projects underway, the new guide will give owners and engineers the specifications and structure they need to source FRP infrastructure products backed by trusted technology. This benchmark document will serve the infrastructure industry for the next two decades.
As a member of ACMA, Creative Composites Group was pleased to be a significant contributor to the successful creation of the new AASHTO guide.
