Stringline setup takes careful planning. Of most importance is the elevation of the stringline, which must be accurate because the sensors controlling the profile pan will adjust to its location. The interval between stakes also is important, particularly for vertical curves. On tangent sections, a maximum staking interval of 25 ft (7.6 m) produces adequate results. A tighter interval is necessary on vertical curves and should be determined based on the curvature rate of change. This tool calculates the rate of change of a vertical curve and, based on this value, provides maximum staking interval recommendations.