Roundabouts on the state highway system are generally  designed to accommodate large vehicles.   When large trucks with wide turning needs are expected to use the  intersection, the roundabout will have a truck apron with a low curb around the  center island.  It might be colored red  or some other color to set it off from the island.  The apron allows truck drivers to roll the  trailer’s rear wheels over the low curb as they drive through the  roundabout.  The low curb discourages  other drivers from using the apron, helping to keep their speeds slow and  consistent.

If you’re a truck driver, stay close to the left side of the entry as you approach the roundabout.  As you pass through the roundabout, your trailer tires may roll over the truck apron.  As you exit, stay close to the left side of the exit.

At a multilane roundabout, you may need to occupy the  entire circular roadway to make the turn.  Signal your intention in advance and claim both lanes when you approach the roundabout.

Truck in roundabout in rural area