Most precast concrete median and guard rail barriers utilize a system of interlocking metal loops for connection purposes. Metal loops are cast into the ends of barrier sections in a pattern that allows these metal loops to overlap when the ends of two barrier sections are aligned. Some variety of connecting pin is then slid through these connection loops to link up and connect the two barrier sections together. The connecting pin itself can come in many different sizes, materials, and configurations depending on the type of barrier and which state is specifying it. This connection hardware may be called a connection pin, a connection bolt, or a connection rod, depending on which state’s drawings you are looking at.
To find out the particulars for your state’s connection hardware, please see the interactive map.