The Montana Department of Transportation (MDT) utilizes two different styles of precast concrete barrier that require connecting pins. The connecting pins for both the 32” standard concrete barrier, as well as the 46” tall concrete barrier, are 1-1/4” ASTM A36 steel round bar with a square plate washer tack welded near one end. The anchor pins for both barrier styles are also A36 steel but are smaller in diameter, have no welded plate, and are required to be galvanized.
The Montana connecting pin is manufactured from 1-1/4″ ASTM A36 round steel with a 1/4″ thick square washer tack welded near the top end. For standard barriers, the connecting pins have an overall length of 23-1/2″. For the 46″ tall barriers, the connecting pins’ overall length is 33″. As with many other State DOT’s, the project engineer may allow the use of a one piece, forged head connecting pin in place of the standard rod with welded washer design as long as the dimensions of the head match those of the washer. Alternate designs would need to be confirmed with the project engineer. The connecting pin details can be seen in Montana Detailed Drawings 606-60 and 606-64.
Montana has three different configurations of hardware for anchoring barrier sections in place. Type 1 anchors are for anchoring to asphalt. These anchors are galvanized 1″ ASTM A36 steel pins, with a 1/2″ bevel on one end, that are driven at an angle through the barrier base. Pre-drilled pilot holes may also be used to aid in installing this style of anchor. Type 2 and Type 3 anchors are for installation on concrete pavement. Both Type 2 and 3 anchors are galvanized ASTM A36 expansion bolts utilized with mounting brackets. Type 2 are 1″ expansion bolts, while Type 3 are 3/4″ diameter expansion bolts. All three types of anchors can be seen in Montana Detailed Drawing 606-62.