Access Management: Why And How

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Access Management Why And How?

• An Introduction To Access
• Management Problems, Principles and Treatments

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Presentation Outline

• What is access management?
• Metro Des Moines access management problems
• An example corridor 14th Street (US 69)
• Benefits of managing access
• Mixes of fixes for access management
• Access management, business vitality, and land
  development
• Accomplishing better access management

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What Is Access Management?

• Providing adequate access to land development
  while simultaneously preserving the safe and
  efficient flow of traffic on the surrounding road
  system.
• In other words, a balancing act.

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An Access Management Problem
All this commotion was caused by a
motorist trying to turn left into a small
shopping center Can you provide too much direct
land access from an arterial street? ABSOLUTELY!
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Costs Of Not Managing Access

• What happens when we fail to do a good job of
  managing access?
• Certain types of crashes happen more frequently
• Rear-end, left-turn, right turn
• Mean travel speeds drop LOS drops
• The investment the public has made in roadways is
  degraded

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Access Management Problem CorridorsDes Moines
Metro
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Examples Of Poor Access Management 14th Street
(US 69)
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NE 14th Access-Related Crashes
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SE 14th Access-Related Crashes
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What Are The Benefits of Managing Access?

• Improved traffic flow
• Improved traffic level of service
• Preservation of investments in capacity
• Higher mean travel speed on arterials
• Lower crash rates
• Poorly-managed roads are 40 to 50 percent less
  safe
• Pedestrian safety can also be improved

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Operations Capacity Is Higher On Better Managed
Roads
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Operations Travel Speed Is Higher On Better
Managed Roads
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Safety Accident Rates Are Lower On Better
Managed Roads
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Safety Iowa Case Studies

• Seven Iowa case studies
• Case studies show nearly a 40 percent average
  reduction in crash rates after access management
  projects were completed.

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Safety Crash Reduction By TypeAfter Access
Management For Iowa Case Studies
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Access Management Treatments Help Pedestrians,
Too
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Access Management Basics

• Limit conflict points
• Separate conflict points
• Remove turning traffic from through traffic lanes
  through channelization
• Reduce speed differential
• Facilitate faster left and right turns

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Conflict Points at Driveways
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Separating Conflict Points Why?

• Conflict points represent opportunities for
  crashes, congestion, and delay
• Drivers can only mentally process one conflict
  point at a time
• Separation provides more time and space for
  drivers to react to the unexpected
• Conflict points and other poor access features
  increase speed differential between through and
  turning traffic
• Speed differential
• Speed of fastest traffic speed of slowest
  traffic
• Greater speed differential generates more rear
  end collisions

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Separating Conflict Points
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Facilitating Turning Movements Important
Strategies

• Fewer, Better Driveways Are Better Than More
  Driveways
• Ways To Improve Driveways
• Increase the turning radius
• Increase driveway width
• Decrease driveway slope
• Include dedicated turn lanes or tapers
• Improve sight distance for turning traffic
• Provide opportunities for internal circulation
  within developments
• Provide dedicated turn lanes where warranted

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Steep Driveways Mean Slower Turns Out Or In
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Dedicated Left And Right Turn Lanes
Channelization goes hand in hand with good access
management.
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Mixes Of FixesCommon Access Management
Treatments

• Driveway consolidation
• Corner clearance
• Alternative access ways (including internal site
  design)
• Continuous two-way left-turn lanes (TWLTL)
• Medians at intersections
• Full raised medians
• We often use combinations of these to manage
  access

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Driveway Spacing And Corner Clearance
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Green Book functional area of the intersection
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Too Many Driveways!
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Good Corner Clearance University Avenue Windsor
Heights
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Alternative Access Ways
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Alternative Access Ways
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Alternative Access Ways South Ames
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Two-Way Left Turn Lane (TWLTL)
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TWLTL 3 And 5 Lane Cross-Sections
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Median At Intersection
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Median At Intersection
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Full Raised Median
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Raised Median 100th Street Clive
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Raised Medians Are Very Effective Safety Devices
Both of these are a big improvement over
an undivided 4 lane
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Access Management And Business Vitality

• Business owners often oppose access changes or
  restrictionsespecially raised medians
• But measured impacts on businesses and land
  development are neutral to positive
• Iowa study results after access management show
• Retail sales levels often improved
• Business turnover rates did not increase
• No impact on commercial land values
• A few individual businesses thought they were
  negatively affected

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Business Surveys Indicate Neutral-Positive Impact
On Business Sales
86 of businesses along newly access
managed routes in Iowa reported similar or
increased sales
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Businesses Choose Locations Based On Where Their
Potential Customers Are
Businesses locate on poor and better managed
routes small changes in access do not seem to
matter much.
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A Must In Access Management

• To have a successful access management program,
  you have to work closely with business and land
  owners and educate them

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Implementing Access Management

• In Iowa, roadway jurisdictions are legally
  responsible for managing access and for providing
  access to properties.
• State legislation governing access in Iowa is
  open to interpretation
• Roadway jurisdictions must provide reasonable
  access
• This has been taken to mean that access to
  roadways does not have to be direct access
• It has also been taken to mean that roadway
  jurisdictions have the right to install raised
  medians even if they diminish businesses access
  to traffic flow in one direction

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Access Management Can Be Implemented Many Ways

• When designing new roadways, through good design
  and the acquisition of access rights
• When rebuilding roadways
• When permitting driveways on roadways
• Prior to new development
• Prior to expanded development
• When regulating land use
• In subdivision regulations, such as driveway
  spacing, indirect access from arterials, or joint
  or cross access regulations
• When applying zoning along arterials

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Poor Land Use Planning Leads To Access Management
Problems Twin Cities, Minnesota
New city park blocks alternative access road route
Warehouse where backage road could be
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Access Management Problems Happen In Rural Areas,
Too
Areas of concern
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And Land Use Decisions Can Make Problems Worse
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Implementing Access Management Is A Team Sport

• Good Access Management Results Depend On The
  Involvement Of
• All government agencies involved
• Adjacent business owners
• Land developers
• The public, including motorists and pedestrians

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Who Wins When Access Is Properly Managed?

• Motorists
• Pedestrians
• Citizens/taxpayers
• Businesspersons and developers, for the most part

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