Dual-Support Breakaway Sign with Modified Fuse Plate and Multidirectional Slip Base

Abstract

Dual-support breakaway signs have been used across the country for more than 25 years and have been credited with saving many lives. A very important feature of this system is the ability of its support to swing up and out of the way when it is struck by an errant vehicle. Another critical feature of the sign system is its ability to withstand wind loads without causing structural damage to the system. A modified dual-support breakaway sign system that improves on both criteria is proposed. A dual-support breakaway sign with a multidirectional slip base performed acceptably during full-scale crash testing. The sign tested consisted of 4.8-m-tall, W6 × 9-wide flange posts with a sign 3.05 m wide by 2.44 m tall. The research indicated that the modified system does not pose any significant hazard for vehicles striking one of the supports at angles of up to 25 degrees. Changing the material of the fuse plate to an A572 Grade 50 steel creates a stronger connection that significantly improves the wind load capacity of the sign system. The proposed material for the fuse plate did not hinder the safety performance of the sign: the fuse plate performed as designed under full-scale testing.