Because study SD90-03 determined the mechanism that causes voids, the Department needs to change its design to accommodate this mechanism. A likely bridge end backfill design alternative is the Wyoming Department of Transportations (WYDOT) which uses a fabric reinforced soil wall. This design incorporates the construction of a vertical void behind the abutment wall to accommodate the abutment movement without causing the backfill to experience lateral pressures.
The feasibility of using other materials for bridge end backfill designs to accommodate the abutment movement should also be investigated. These materials should either be able to create a vertical void behind the abutment or exhibit engineering properties that will alleviate lateral pressures. Rubber chips from discarded tires and expanded polystyrene blocks are examples of materials which may warrant investigation.