TM5-803-14
clearance of 50' should be maintained between
(3) Prohibition of critical movements at the
access drives and major intersections. MTMC pro-
access drive.
vides further guidance on recommended corner
(4) Relocation of the access drive to another
clearances.
access road.
c. Sight Distances. Adequate sight distance
d. Left turns. Access should limit conflict on the
should be provided for vehicles entering and exit-
through road by preventing certain maneuvers
ing the access drive. Figure 6-2 illustrates safe
(e.g., left turns.) Left turns should be prohibited
sight distances as determined by table 6-4. If sight
under the following conditions:
distance is not adequate, the following alternatives
(1) Inadequate corner clearance.
should be considered:
(2) Inadequate sight distance.
(1) Removal of sight obstructions.
(3) Inadequate driveway spacing.
(2) Relocation of the access drive to a more
(4) Median opening too close to another me-
favorable location along the access road.
dian opening.
Figure 6-2. Sight Distances for Access Drives.
Table 6-4. Minimum Sight Distances along Access Road from Access Drive to Allow Vehicle to
Safely Turn Left or Right onto Road (in Feet).
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 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 10 mph.
3. Turns are 90-degree.
4. The access road and the access drive are on level terrain.
Operating
40
Speed (mph)
50
20
30
Direction
Right
Right
Right
Right
Left
Left
Left
Left
970
590
900
540
360
320
170
210
Passenger Car
450
1530
520
920
1510
230
920
360
Truck
6-3
Previous Page
