Breakaway couplings for transportation structures

A breakaway assembly designed to fail when subjected to a predetermined minimal impact force, the breakaway assembly having a generally vertical pole structure having a top end and a bottom end, a pole base connected to said bottom end of said generally vertical pole structure and provided with a plurality of vertically disposed openings, a supporting foundation in a constructive relationship to said pole base and having a plurality of foundation anchor bolts extending vertically upwards from said supporting foundation, wherein the improvement comprises:

• a plurality of breakaway couplings made of a free-cutting brass alloy with a composition of 58-65% copper, 33-39% zinc, and 1-5% lead, connecting said pole base to said supporting foundation;
• wherein said plurality of breakaway couplings individually comprise of:
• a multi-sided, elongated body;
• said multi-sided, elongated body having an upper end, a lower end, an internally threaded bore extending between said upper end and said lower end of said multi-sided, elongated body, and an outer surface;
• said outer surface having a single horizontally disposed, circumferential groove extending partially into said multi-sided, elongated body towards said internally threaded bore and extending to a critical notch depth, wherein said critical notch depth is of an enabling failure depth;
• a critical support depth of an enabling sustained fatigue life thickness, in corresponding relation to said single horizontally disposed, circumferential groove;
• and
• said upper end of said multi-sided, elongated body is adapted to receive a vertically oriented pole base anchor bolt threadably engaged therein and secured with a bonding agent.

A breakaway coupling made of a durable material for joining a generally vertical pole structure to a supporting foundation, the breakaway coupling comprising:

• a multi-sided, elongated body of single piece construction;
• said multi-sided, elongated body having an upper end, a lower end, an internally threaded bore extending between said upper end and said lower end of said multi-sided, elongated body, and an outer surface;
• said outer surface having at least one horizontally disposed, circumferential groove extending partially into said multi-sided, elongated body towards said internally threaded bore and extending to a critical notch depth, said critical notch depth is of an enabling failure depth to enable failure of the breakaway coupling only along said at least one horizontally disposed, circumferential groove upon application of a predetermined minimal impact force and said critical support depth is of an enabling sustained fatigue life thickness to enable a sustained fatigue life of the breakaway coupling;
• wherein said at least one horizontally disposed, circumferential groove is located at a bolt meeting point substantially equal distant between said upper end and said lower end of said multi-sided, elongated body;
• said at least one horizontally disposed, circumferential groove is a single horizontally disposed, circumferential groove having a V-shape of an angle of between 5 degrees and 45 degrees and wherein said critical notch depth is between 0.125 inches and 0.170 inches;
• and,
• said multi-sided, elongated body is a free-cutting brass alloy with a composition of 58-65% copper, 33-39% zinc and 1-5% lead.