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I-Beam Bridge Case Study: Short Span, Long Life, Low Cost


Trail organizations, parks, and recreation councils are always looking into using lightweight and long-lasting material to create small spanning walkway solutions that minimize crossing and trail maintenance. To meet these objectives on a trail system with a small stream crossing, a trail association in the northeastern United States turned to E.T. Techtonics to design, manufacture, and fabricate a small walkway solution using FRP material. 



While making trail improvement decisions, the trail association looked for a long-lasting alternative material for this project instead of wood. The previous structure was installed in the late '80s. Thanks to father time and mother nature, the wood structure was structurally unsafe and was in significant need of renovation.

With this in mind, the organization turned to FRP material as a possible solution, which was the first time this group has worked with the material as a walkway solution. After some research, they reached out to E.T. Techtonics, looking for a possible solution to this small passing. The group had the following requirements which needed to be met to make this new bridge solution work for them:

  • Lightweight
  • Simple assembly
  • Zero to no maintenance
  • Long material life
  • Pre-Designed
  • Proven Success
  • Cost-Effective



The E.T. Techtonics team was able to design a short span solution to solve the customer's problems. Since the span of this structure was under 25', an I-Beam bridge was able to be utilized in this situation. Unlike the truss-style design of bridges that are E.T. Techtonics' flagship product, the I-Beam style bridge uses fewer members and is much more cost-effective than a truss-style structure at short lengths. The design of the structure used FRP C-channels, square tubes, angles, and wood decking. With lightweight FRP, the group was able to carry in the component parts to a site with minimal access for heavy machinery and equipment. This bridge also featured FRP hand railing on the side to protect users.

Parts of this structure were manufactured by Creative Pultrusions in Pennsylvania and kitted by our local fabrication group, who have had 30 years of experience with FRP material. The bridge was shipped unassembled to the trail organization for assembly. After a day of hiking in the parts, the bridge was installed entirely on-site in less than 4 hours. The association was very impressed with its first installation for an FRP walkway. They were amazed at how lightweight the components were, and how quick assembly was. They are looking forward to using this material again on future projects they have coming up.