Overview of Access Management

1
Overview of Access Management

• May 3, 2001
• CE 392

2
Acknowledgments

• Vergil Stover and Robert Layton
• Transportation Research Institute
• Oregon State University
• and
• Oregon Department of Transportation

3
Access Management
A Critical Traffic Management Strategy
4
What is Access Management?
5
Access Management Includes

• Driveways, Spacing, and Design
• Median Use, Design and Openings
• Provision of Turn Lanes
• Proper Spacing of Traffic Signals
• Inter-parcel Circulation

• Freeway Interchanges
• Functional Class of Facility
• Functional Area of Intersections
• Local Road Infrastructure

6
Why Do We Manage Access?

• The final product of Access Management is the
  safe and efficient flow of traffic through the
  road system and access to the destination.

7
What are the Benefits of Access Management?

• Safety
• Fewer and less severe crashes
• Less auto-pedestrian conflicts
• Efficiency
• Less stop and go traffic
• Reduces delay
• Increased and preserved capacity
• Reduced fuel consumption
• Preservation of investment in the roadway system

8
What are the Benefits of Access Management?

• Aesthetics
• More attractive corridors
• Improved community appearance
• Livable Communities
• Enhances community character
• Preserves neighborhood integrity
• Preservation of private investment in abutting
  properties
• Lower vehicular emissions

9
How Can We Manage Access?

• Medians
• Auxiliary Lanes
• Signal Spacing
• Driveway Location and Design
• Driveway Spacing
• Corner Clearance
• Joint Cross Access
• Reverse Frontage

10
What are

• Access?
• Accessibility?
• Movement?
• Mobility?

11
(No Transcript)
12
Who Benefits from Access Management?

• Motorists
• Pedestrians and Bicyclists
• Transit Riders
• Property Owners
• General Public

13
(No Transcript)
14
(No Transcript)
15
(No Transcript)
16
(No Transcript)
17
(No Transcript)
18
Access Design Issues

• Intersection Hierarchy
• Functional Intersection Area
• Speed Differential
• Signal Spacing
• Number of Conflicts
• Conflict Areas
• Use and Design of Medians
• Visibility of Access Connection

19
Access Design Objectives

• Design should fit natural paths of vehicles.
• Intersection should be as level as possible.
• Adequate sight distance should be provided.
• Intersections should be evenly spaced.
• Traffic signals should be spaced for efficient
  progression movements.

20
Intersection Design Principles

• Coordinate Design and Traffic Control
• Avoid Complex Maneuvers
• Limit Number of Conflict Points
• Separate Conflict Areas

21
Intersection Design Principles -Continued

• Favor Major Flows
• Minimize Conflict Areas
• Segregate Movements
• Pedestrians and Bicyclists
• Vehicle Types

22
Driver and Vehicle Considerations

• Design Vehicle Dimensions
• Vehicle Turning Path and Speed
• Deceleration Rate
• Acceleration Rate
• Speed Differential Between Vehicles
• Driver Perception-Reaction Time

23
Roadway Design Elements

• Signal Spacing and Perception
• Medians
• Auxiliary Lanes
• Channelization
• Driveway Design and Location
• Frontage Roads
• Sight Distance

24
(No Transcript)
25
Speed Differentials

• All Traditional Driveway Designs Result in a
  High-Speed Differential
• High-Speed Differentials Produce High Crash Rate
  Potentials
• Turn Bays are the Only Means of Limiting the
  Speed Differential Between Turning Vehicles and
  through Traffic

26
Median Design Elements

• Type
• Width
• Geometry of Openings
• end treatment
• length of opening
• Spacing of Median Openings

27
Median Types

• Non-Traversable
• Traversable
• Two-Way Left-Turn Lane
• (TWLTL)

28
Consideration of Unsignalized Intersection Access
Spacing

• Stopping Sight Distance
• Intersection Sight Distance
• Maneuver Distance
• Right-turn Conflict Overlap
• Maximize Egress Capacity
• Corner Clearance

29
(No Transcript)
30
Driveway Design Elements

• Width
• Driveway Length
• Return Radius
• Lateral Offset
• Approach Angle
• Approach Flare

31
How Can Access Management Improve Safety and
Traffic Operations?

• Limit the Number of Conflict Points
• Separate Conflict Areas
• Remove Turning Vehicles from Through Traffic
  Lanes
• Reduce Conflicting Volumes
• Improve Roadway Operations
• Improve Driveway Operations

32
(No Transcript)
33
(No Transcript)