A curve should always meet the minimum turning requirements of the vehicles expected to use the road. Log trucks require a minimum of a 50-foot radius curve. Flatbed trucks used to haul heavy equipment (lowboys) must have at least a 70-foot radius curve. Grade should be adjusted through the curve to provide for safe handling of heavy equipment. See Table 2 for grade adjustments.

Center stake method
Using a string or tape the length of the radius, find the center of the curve by trial and error (Figure 2). Do this by moving back and forth along the straight road segments (tangents) leading into and out of the curve with the tape at a right angle to the road until a common point, the center, is found. Now scribe an arc along the ground marking the curve. Place stakes at suitable intervals to mark the curve starting at the point of curvature (PC) and ending at the point of tangency (PT)