30 November 1998
(2) Relocation of the access drive to a more favorable location along the access road.
(3) Prohibition of critical movements at the access drive.
(4) Relocation of the access drive to another access road.
Table 2-4. Minimum Sight Distances
NOTE: Sight distances are based on the following assumptions:
1. Upon turning left or right when exiting the access drive, the vehicle accelerates to the operating speed of
the access road without causing approaching vehicles to reduce speed by more than 16 kph (10 mph).
2. Upon turning left when entering the access drive, the vehicle clears the near half of the access road
without causing approaching vehicles to reduce speed by more than 16 kph (10 mph).
3. Turns are 90-degree.
4. The access road and the access drive are on level terrain.
d. Left turns. Prevent left turns on the through road to limit conflict under the following
(1) Inadequate corner clearance.
(2) Inadequate sight distance.
(3) Inadequate driveway spacing.
(4) Median opening too close to another median opening.
e. Entrances. Design entrances to and from access drives to include:
(1) Minimum turning radii for the largest vehicle expected to use the site.
(2) A minimum 3.1m (10-ft) wide traffic island where entry and exit lanes into the site
(3) Minimum throat widths and lengths to accommodate incoming and outgoing traffic.
Figure 2-3 illustrates throat dimensions.
(4) Sufficient width to accommodate single- or double-lane traffic depending upon the
design vehicle using the route.
(5) A minimum 30.5m (100 ft) unobstructed sight distance for turns from parking lots
and service drives onto the access drive.