Abstract: A slip base support system for tubular posts. The post supporting a highway sign or other highway roadside device is held in a casting that has a triangular, multi-directional base plate. The base plate mates with a similar shaped ground plate, and the two plates are held together with bolts oriented in notches in the apexes of each triangle. Upon impact by a vehicle, the post and support casting break away from the ground plate by ejecting one or more of the bolts laterally from the notches. The post is held within the casting after impact by an internal locking pin, which is retained within the post by grommets, thus minimizing the projectile missiles after impact. To facilitate breakaway, two sheets of galvanized steel having a low coefficient of friction are positioned between the base plate and ground plate. After impact, nearly all parts of the system, including the post, casting, ground plate and bolts, are able to be re-used.

Abstract: A slip base support system for tubular posts. The post supporting a highway sign or other highway roadside device is held in a casting that has a triangular, multi-directional base plate. The base plate mates with a similar shaped ground plate, and the two plates are held together with bolts oriented in notches in the apexes of each triangle. Upon impact by a vehicle, the post and support casting break away from the ground plate by ejecting one or more of the bolts laterally from the notches. The post is held within the casting after impact by an internal locking pin, which is retained within the post by grommets, thus minimizing the projectile missiles after impact. To facilitate breakaway, two sheets of galvanized steel having a low coefficient of friction are positioned between the base plate and ground plate. After impact, nearly all parts of the system, including the post, casting, ground plate and bolts, are able to be re-used.