Abstract: The pivot pin (26) connects the gate arm (14) and adapter (28) to the extension plate (24), and cross pin (32) supports the supporting pins (34) unless shear pins (50) are removed or destroyed. When the shear pins are removed and the gate arm moves horizontally (FIG. 2), its support pins move toward a parallel position with respect to the cross pin (32), which would normally allow the gate arm to drop to the ground in a disabled position. When maintenance is to be performed on the gate arm, the temporary retainer nut (10) is threaded onto the lower end (48) of the pivot pin to keep the gate arm from falling and the shear pins (50) are extracted so that the gate arm can be moved through a horizontal arc out of the road blocking horizontal position without falling to the ground.