A driveway's turn radius describes the sharpness of the road's curve as it transitions to the driveway. A larger turn radius gives vehicles a greater distance to cover as they move into the driveway from the main road. The increased distance reduces the vehicles' need to decelerate as they make the turn. This then reduces the chance that other vehicles will collide with the one that turns. According to Oregon State University data, if the speed rises from 10 to 35 miles per hour, the chance of a a collision increases 90 times.
Note the point on the main road where the road begins to curve.
Lay one end of the tape measure on this point.
Extend the tape measure away from the road so that it runs parallel with the driveway.
Note the point at which the curve ends and the driveway continuous completely straight.
Lay one end of the second tape measure on this point.
Extend the tape measure away from the driveway so that it runs parallel with the main road.
Note the measurement on either tape measure where the two strips intersect. For instance, a driveway with a wide curve may have a turn radius of 35 feet.
