Section 6: Entrance and Exit Ramps
Anchor: #i1003963Overview
Entrance and exit ramps are the primary means of accessing freeways and other controlled access facilities. The unique feature of these elements is that vehicles are either accelerating or decelerating and merging with other traffic. For this reason there is significant potential for driver error that could lead to an accident.
Anchor: #i1003973Safety Considerations
Safety is a primary consideration in ramp design. Drivers must be able to see the approaching traffic stream with sufficient time to adjust their speeds and merge with the traffic safely. Extra care must be taken in the design of the areas around a ramp to ensure that nothing will obstruct a clear view of approaching traffic.
Anchor: #i1003983Visibility
Careful consideration must be given to the design of planting or other above ground improvements in the vicinity of an entrance or exit ramp. Plants in particular should be selected and placed with care so that growth over time will not create a visual obstruction.
Anchor: #i1003993Placement of Plants and Other Features
Some basic rules that should be observed when developing landscape and aesthetics plans in the vicinity of entrance and exit ramps include:
- Anchor: #DGHVMWFO
- avoid placing any vertical obstruction between the ramp and the traveled lanes over its entire length Anchor: #VBNBGDGJ
- plants should be avoided in the zone between the beginning of the ramp and the gore of the acceleration or deceleration lane Anchor: #WEUWQARW
- if trees are placed between the frontage road and the ramp they must of a type that have an ascending branch pattern that will remain at least 6 ft above the ground Anchor: #HGAUIFHR
- shrubs and ground cover materials should not be used in the gore or zone between active travel lanes and the ramp since they could become a visual obstruction