The New Mexico Department of Transportation (NMDOT) utilizes several types of concrete barriers. For permanent installations NMDOT typically calls for slip formed or cast-in-place concrete barriers that do not require connecting or base pins. However, for temporary pre-cast concrete wall barriers, NMDOT does require connecting pins and anchoring bolts. Connecting Pins are a galvanized, welded washer design made from ASTM A36 steel. Anchor bolts are required to be galvanized ASTM A325 high strength steel in one of three different styles.
The New Mexico temporary wall barrier connecting pin is manufactured from 1-1/4″ ASTM A36 round steel that then has a circular washer fillet welded near the top end. The entire rod and washer assembly is then hot dip galvanized. An optional 1/2” bevel may be added to the bottom of the connecting pin at the contractor’s request.
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 on pages 20-1/5 and 20-2/5 of Standard Drawing 606.
New Mexico has three different configurations of hardware for anchoring barrier sections in place. All three are 7/8″ diameter galvanized high strength A325 rods with a large square plate washer.
- Type 1 thru-deck anchors are for anchoring to existing bridges and are only used when specified by the engineer. They use a rod threaded on each end installed through the existing bridge deck and secured with a plate and nut on each end.
- Type 2 adhesive bonding anchors are for installation on bridge decks and cement pavement. They are a fully threaded rod installed in drilled holes with adhesive epoxy, a square plate, and a nut (shown).
- Type 3 anchor bolts are utilized on bituminous pavement or soil and are of variable length and configuration specified by the engineer.
All three types of anchor bolts, as well as the deck/barrier washers, can be seen on page 20-3/5 of Standard Drawing 606.