ability to see a 2.0-ft-high (0.61-m) object in the roadway without being blocked by
the pavement surface. The height of eye for the driver used in the calculations is 3.5 ft
(1.07 m).
The sight distance on a sag vertical curve is dependent on the driver’s being able to
see the pavement surface as illuminated by headlights at night. The height of the headlight
is assumed to be 2.0 ft (0.61 m), and the height of the object is 0.0. The upward divergence
angle of the headlight beam is assumed to be 1°.