Structures Design

Structures Design - Transportation Innovation

Segmental Block Walls (SBW)


Segmental Block Walls (SBWs) may be used as an alternative to most MSE walls, but not to support spread footings. The construction of SBWs is achievable without the use of heavy equipment or cranes. Interlocking CMUs are used to provide a mechanical connection of the geotextile reinforcement to the wall face.

The primary difference between SBW and GRS is the frequency of the reinforcement. SBW facing blocks may be used for GRS Abutments  and GRS Walls.

Design Criteria

Follow the design criteria of MSE walls in accordance with the FDOT Structures Manual and the AASHTO LRFD Bridge Design Specifications, 6th Edition. The maximum geo-synthetic vertical spacing is the lesser of two facing blocks in height or 30 inches. Provide a minimum horizontal distance between the edge of the travel lane and the wall equal to one-half of the wall height.


Include Developmental Specification 548 in the Specification Package when SBW are an allowed alternate on the project.

Implementation Plan

Segmental Block Walls are available for immediate implementation with authorization from SDO and concurrence from the District on limited projects.

Usage Restrictions / Parameters

SBWs may be considered for walls having heights up to 40 feet. When the wall face is within the clear zone of an adjacent roadway, the facing blocks must be solid from the bottom of the wall to 8 feet above the proposed grade.

Contact Information

Steven Nolan
Senior Structures Design Engineer
Phone: (850) 414-4272