Keystone SRW test helps FHWA advance earth retention system practice

Keystone Retaining Wall Systems’ KeySystem III was recently evaluated under the Federal Highway Administration’s new Innovations, Developments, Enhancements and Advancements (IDEA) program. Administered by the American Society of Civil Engineers’ Geo-Institute, the technical evaluation serves to improve earth retention systems technology and installation methods.


Austin, Texas-based TRI Environmental subjected Keystone Compac III to sustained load connection testing, results from which contributed to the ASCE Geo-Institute findings for the Federal Highway Administration Innovations, Developments, Enhancements and Advancements program evaluation.

Structural applications for such systems include retaining walls, headwalls/wingwalls, bridge abutments and roadway supports on transportation, commercial, industrial, recreational, public works and residential projects. Approved or recognized by 30 state agencies, KeySystem III is designed to the highest standards and unique requirements of the transportation sector. It consists of dry-cast concrete Keystone Compac III modular units and TenCate Geosynthetics’ Miragrid XT polyester geogrid soil reinforcement. The leading commercial retaining wall product on the market, Keystone Compac features an open core design and pin connection system.

The IDEA assessment updates a 2012 KeySystem II evaluation by the ASCE Highway Innovative Technology Evaluation Center (HITEC). It considered Keystone material, design, construction, performance and quality assurance information against state-of-the-practice criteria outlined in the IDEA protocol. For submittal purposes, the methodology used for KeySystem III follows the current AASHTO LRFD Bridge Design Specifications and FHWA guidelines for Design and Construction of Mechanically Stabilized Earth Walls and Reinforced Soil Slopes.

KeySystem III updates include improved Compac III design features and current information on soil reinforcement. KeySystem III is the first concrete modular block system paired with extensible reinforcement that was previously subject to HITEC, but is now evaluated under IDEA. — Keystone Retaining Wall Systems, Minneapolis,