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Access Management Principles Presentation

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Contact Information: Neil Spiller at

Slide 1. Access Management Principles

Introduction and Overview

Neil Spiller
FHWA, Washington, D.C.

A circular graphic displaying the interaction of Right to property access and efficient traffic throughput.

Slide 2. Presentation

  • General overview
  • Benefits and Consequences
  • Access Management in Practice
  • Elements of an AM Program

Slide 3. Part 1


Slide 4. What is "Managing Access"?

Managing and Planning the Spacing and Design of:


Median Openings

Traffic Signals


A graphic design showing a driveway, median opening, traffic signal, and interchange.

Slide 5. Definition of AM

FORMAL: Access management is the programmatic control of the location, spacing, design, and operation of driveways, median openings, interchanges, and street connections to a roadway. (TRB Manual)

INFORMAL: Where the road meets the driveways

Slide 6. Purpose of AM: Balance Mobility vs. Access

This figure is a conceptual roadway functional hierarchy showing that as access increases, mobility decreases. Freeways have limited access and high mobility, whereas local streets have increased access but lowered mobility.

Slide 7. A Very Brief History of AM
part 1 of 4

New Jersey 1902 – established "speedways" for horses and bicycles. "No public streets or other highways shall cross or intersect the speedway at grade without consent of the county"

U.S. Supreme Court 1906 – decided that access control along highways was a sovereign power of the states.

Slide 8. A Very Brief History of AM
part 2 of 4

Between 1900 and 1920 the number of automobiles grew from 8K to 10M and lobby groups emerged (e.g., AAA and AASHO)

1919- DDE undertook a transcontinental military convey from D.C. to San Francisco (62 days)

1921 Federal-Aid act established a system of national routes

Slide 9. A Very Brief History of AM
part 3 of 4

In 1920's it became apparent that automobile (related) deaths were soaring.

In 1937 NY and RI established the first statewide statutes that included "abutting" access control and required permits and reviews as part of their state route adoption plan

By late 1940's almost every state legislated permitting accesses to some degree and court decisions began to confirm that public safety and mobility essentially trumped a landowner's absolute right to access at any point

Slide 10. Basic "right to access"

A property owner has right to have access (i.e., not to be landlocked)

but does NOT have right to expect absolute access at any point,

NOR should they expect compensation for relocated access as long as the government shows justifiable cause and least-impact.

Slide 11. A Very Brief History of AM
part 4 of 4

National standards for individual driveway design were developed in 1960 – AASHO "An Informational Guide for Preparing Private Driveway Regulations for Major Highways"

NCHRP Report 121 (1971) "Protection of Highway Utility" stands as one of the earliest, most recognized discussions of access control

Beginning of modern AM – credited to Colorado, 1979, when they created 1st comprehensive principals of AM and spelled out the safety, aesthetic and delay-reducing benefits of AM "incorporated" into statute

Slide 12. Colorado, 1979

"The lack of adequate access management on the highway system and the proliferation of driveways and other access approaches is a major contributor to highway accidents and the greatest single factor behind the functional deterioration of highways in this state. As new accesses are constructed and signals erected, the speeds and capacity of the roadways decrease, and congestion challenges to the motorist increase."

-- Colorado State Highway Access Code

Slide 13. National Perspective

  • "The lack of access control along arterial highways has been the largest single factor contributing to the obsolescence of highway facilities"

    NCHRP Report 121 Protection of Highway Utility
  • "Every study since the 1940's has indicated a direct and significant link between access frequency and accidents"

    International R/W Assoc. conference paper, 1999

Slide 14. Part 2

Benefits and Consequences

Slide 15.

Driveways are inevitable and necessary but as their numbers go up, so too does the propensity for accidents in that corridor.

Picture intending to show how multiple access opportunities can be "busy"

Slide 16. Benefits of AM

  • Preserve integrity of the roadway system
  • Improve safety and capacity
  • Extend functional life of the roadways
  • Preserve public investment in infrastructure
  • Preserve private investment in properties
  • Provide a more efficient (and predictable) motorist experience
  • Improve "thru" times through a corridor
  • Improve aesthetics (less pavement, more green)

Slide 17. Groups Who Benefit

Which groups will benefit from good AM?

  • Motorists
  • Cyclists
  • Peds
  • Business Owners
  • Communities

Slide 18. % of Driveway Crashes by Movement

A figure showing the percentage of driveway crashes by movement.  From different turn locations of a driveaway to a street and vice versa.

Here's a scoop!

The majority of access-related crashes involve LT's (63%)

Image of a rolled up newspaper

Slide 19. Composite Crash Rate Indices

Crash rate indices increase as # of access points per mile increases

A graph displaying the Crash Index: Ratio of crashes to access points per mile by number Access points per mile.

Slide 20. AM in the Transportation and Land Use Cycle

Graphic drawing. The Transportation Land Use Cycle. As land use changes, so too does the transportation network, to accommodate it. A graphic showing Access Management applied through physical means; Arterial Improvements, Increased Accessibility, Increased Land Use; Access Management applied here through administrative means; Land Use Change, Increased Traffic Congestion, Increased Traffic Conflict and Deterioration in Quality of Traffic Flow.

Slide 21. What's the bottom line?

Over-arching Goal of AM:

Limit  the number and impact of driver decision and conflict points from impacting on through traffic.

Slide 22. Traffic Conflict

Think of a single traffic conflict as one rock in a pond. The ripples are easy to see and are predictable. However, when dozens of rocks are thrown in at once, the ripples are dynamic, they create chaos, and it is difficult to avoid one at the cost of another.

Slide 23. Conflict Points

Each access point creates potential conflicts between through traffic and turning traffic.

Graphic drawing of a Diverge conflict

Graphic drawing of a Merge conflict

Graphic drawing of a Crossing conflict

Graphic drawing of a Stopping conflict

Graphic drawing of a Weaving conflict

Slide 24. Conflicts

A graphic of two drawings. The first drawing displays 32 potential conflicts at a standard 4-way intersection; the second drawing displays 8 potential conflicts when a partial median (one-direction LT) is added.

(and don't forget pedestrian and bicycle movements too!)

Slide 25. Consequences of Poor AM

  • Increase in crashes and crash rates
  • Poor capacity throughput
  • Increased delays
  • Reduced roadway efficiency
  • Potential for unsightly strip development
  • Decreased property values
  • Potential for unwanted cut-thru traffic
  • Potential for less desirable experience, hence, less customers will want to make the trip

Slide 26. Effect of Speed Differential to Propensity for Crashes

A chart displaying Relative Crash Ratio by Speed Differential (Miles per Hour). The crash ratio increases as the speed increases.

Slide 27. How to improve "Consequences"

  • Unclutter the corridor ("Pruning") Direct where driveways are best suited
  • "Assign" turn movements by defining and separating them
  • Develop guidelines for property access, thru traffic, and hierarchy of streets
  • Enforce against violations and poor practices in siting driveways and streets

Slide 28. Part 3

Access Management in Practice

Slide 29.

Use non-traversable medians to separate traffic and direct motorists where to access properties.

Use turn lanes to queue separate movements and to "free up" through movements

Major arterial street with median and left turn bays.

Slide 30. Driveway Bypass Lane

Where restricted from placing a median, can you install a bypass lane?

A graphic drawing of a Bypass Lane treatment showing the Approach Taper, Bypass Lane and Departure Taper.

Slide 31. Median Redesign


  1. Increased separation between intersections
  2. Introduction of U-turns to replace former movements

A graphic drawing showing introduction of a median between intersections may result in U-turns at the up- and downstream intersections.

Slide 32. Results—Fewer accidents on 'Managed' roads

Chart showing non-managed arterials have higher accident rates than managed ones.

Source: "Colorado Access Control Demonstration Project" – 1985

Slide 33. Results—Higher 'thru' speeds on 'Managed' roads

Effects of Access Management on travel speeds in the P.M. peak hour

Chart showing travel speeds are typically increased on managed arterials vs. non-managed arterials.

Slide 34. Signal Spacing Variables

  • "Tweak" these . . .
    • Intersection spacing
    • Overall cycle lengths
    • Cycle phasing
  • To “Seek” these . . .
    • Progression speed
    • Progression efficiency

Slide 35. Relationship between cycle length, signal spacing, and speed

Empty Cell 1/4-mile 1/3-mile 1/2-mile
30 MPH 60 sec 80 sec 120 sec
40 MPH n/a 60 sec 100 sec
50 MPH n/a 50 sec 80 sec

Slide 36. What methods are used?

  • Permits, legislation and corridor planning
  • Medians
  • Auxiliary lanes
  • Signals and signal spacing
  • Driveway location, spacing, and design
  • Corner clearance
  • Cross-access and joint access
  • Frontage roads and connectors

Slide 37. Who is Responsible for AM?

Professionals that guide urban development

  • Planners
  • Engineers
  • Architects
  • Approval agents (Boards, Councils, etc.)
  • Developers
  • Land use attorneys
  • Agency staff

Non professionals

  • Citizens, motorists
  • Property Owners
  • Ad-hoc groups (pedestrians, bicycles, social change)

Slide 38. What is "Functional Intersection Area" and why is this important?

The influence area associated with a driveway includes

  • The impact length (distance back at which cars begin to be affected)
  • Perception-reaction distance
  • And the "car length"

Upstream length > Downstream length

Slide 39.Functional Intersection Area

The upstream and downstream areas of influence that affect driver decision. Note that closely spaced driveways and intersections have overlapping areas.

Elements that impact the functional intersection area:

stopping sight distance; RT-out acceleration; slowing to turn; perception-reaction time; queue storage; etc., are there more?

A graphic drawing displaying the functional area of an intersection decreases with distance from that intersection.

Slide 40. Application of 'Access Window'

A graphic drawing of three versions of decreasing access "window" opportunities between intersections; Window for left or right, Window for right turn only, and No window on higher street.

Slide 41. Different types of Access Controls

  • "Police" power
  • Eminent domain
  • Condemnation
  • Statutes and statutory designation

Slide 42. In plain English?!

An agency uses eminent domain to purchase or "take" the right of access.

An agency uses their police power to approve or deny the application for a driveway and impart public safety

Slide 43. Part 4

Elements of an AM Program

Slide 44. Elements of an AM Program

  • Have administrative rules, ordinances or guidelines
  • Educate your boards, councils, and public
  • Establish an approval authority
  • Have geometric design standards
  • Provide staff training and education re: policies
  • Monitor approvals (inspect) and conduct agency evaluations
  • Develop an request/approval process and fees, etc.
  • Provide consistent and justifiable application of standards
  • Document meetings, contacts, and written communications
  • Allow for appeals and justified deviations/exceptions

Slide 45. Every stakeholder needs to be "on board" with the plan and aware of the consequences of, and need for, guidance, structure and goal

Empty Cell Schools Sports Access Management
Oversight School Board Owner Mayor, Council, Board
Leadership Principal Coach DPZ, DPW
Day-to-day execution Teachers Players Staff
Guiding principles Lesson Plans Playbook, rules Design statutes
Stakeholders Parents Fans Motorists and property owners
Product Graduates Quality of effort and wins / losses Improved traffic progression, safety

Slide 46. Have a plan — stick to it!

A graphic figure drawing. The top part of the Figure showing many accesses due to uncontrolled permitting. The bottom part of the Figure showing lesser accesses due to proper permitting.

Slide 47. Levels of Approval

  • Federal interstates / State highways
  • Local highways and streets
  • Local site plan approvals must meet other agencies' regulations (zoning, R/W, EPA)
  • Adopted Master Plans
  • Zoning and long range planning must be considered
  • Other stakeholders? Adjacent/abutting property owners? Public?

Slide 48. Traffic Impact Study Areas

A figure showing four parts; Top first part: very small traffic study area for a very small project impact. Second part: Small traffic study area for a small traffic project impact. Third part: Medium traffic study area for a medium traffic project impact. Bottom fourth part: Large traffic study area for a large traffic project impact.

Slide 49. FHWA's Role

  • To champion the role that AM serves in improving safety and reducing delay
  • Increase awareness of, and benefits of . .
  • To sponsor AM-related studies and enable academic research
  • To educate (through NHI courses, et al)

Key Products

An image of the Benefits of Access Management Tri-fold
"Benefits of Access Management" Tri-fold

An image of the Access Management DVD cover
AM Resource DVD

An image of the Safe Access is Good for Business Handout and CD
Public Meeting Handout and CD

Slide 50. FHWA does not . . .

  • Write AM guidelines for states, et al
  • Mandate AM regulations (although we certainly "advise") as a general rule
  • Make decisions on new access' on interstates (the states do)

Caveat — because FHWA oversees Federal funding, we have a mandated role in reviewing, recommending, and approving some state-sponsored activities regarding (mostly) the interstates

Slide 51. Federal Aid Highway System
(Routes eligible for Federal aid)

  • Interstate System
    • Dwight D. Eisenhower National System of Interstate Highways
    • Routes of highest importance
    • Shall not exceed 43,000 mi.
  • National Highway System
    • Shall not exceed 178,250 mi.
    • All routes on the Interstate System are part of NHS
    • Includes STRAHNET routes

Slide 52. FHWA Functional Classification Guidelines

Principal arterials
Minor arterial streets ("roads" in rural areas)
Collector streets ("roads" in rural areas)
Local Streets ("roads" in rural areas)

For Rural, Urban, or Small Urban designations

Slide 53. TRB's website

Composite picture of products available through the Web site

Slide 54. Managed Access Success!

Office of Operations