NSBA Releases Guide to Steel Highway Grade Separation Bridges

Grade separation bridges—particularly freeway overpasses—are among the most common bridge types in the U.S., yet their long-term performance is heavily influenced by early layout and detailing decisions. To help bridge owners and designers achieve more durable, safer, and cost-effective structures, the National Steel Bridge Alliance (NSBA) developed the Guide to Steel Highway Grade Separation Bridges.

This guide focuses on the key planning and preliminary design decisions that drive bridge performance, including span arrangements, clearances, girder selection, substructure layout, and corrosion protection strategies. Rather than serving as a detailed design manual, it complements AASHTO and NSBA resources by emphasizing practical considerations that improve service life, reduce maintenance needs, and enhance overall value.

Through clear explanations, recommended practices, and an example bridge layout, the guide helps engineers evaluate trade-offs between initial cost and long-term performance—supporting better decisions that lead to more resilient and efficient steel overpass bridges.

Download the guide to optimize the layout and detailing of steel grade separation bridges for improved durability, safety, and lifecycle value.

Learn more about the guide directly from the principal author, Michael Culmo, PE, Chief Bridge Engineer at CHA Consulting, Inc., in this recorded AISC/NSBA webinar. In this webinar, Michael explains how designers can use the new Guide while also sharing practical insights and best practices for safer, more resilient transportation infrastructure.