Purpose
The rock lands are usually set at the start of a project to
help the contractor calibrate the spreader box and assure that the
correct aggregate rate is being applied. If the aggregate runs out
before reaching the marker at the end of the rock land, the rate
is too heavy. If there is aggregate remaining at the end of the
rock land, the rate is too light. This is based on the assumption
that the truck is carrying the predetermined amount of aggregate.