access management: why and how? an introduction to access management problems, principles and...

Access Management: Why And How?

An Introduction To Access Management Problems, Principles and Treatments

Presentation Outline

What is access management?Metro Des Moines access management problemsAn example corridor: 14th Street (US 69)Benefits of managing access“Mixes of fixes” for access managementAccess management, business vitality, and land developmentAccomplishing better access management

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.

An Access Management Problem

All this commotionwas caused by a motoristtrying to turn leftinto a small shoppingcenter

Can you provide toomuch direct landaccess from anarterial street?

ABSOLUTELY!

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

Access Management Problem Corridors—Des Moines Metro

Examples Of Poor Access Management: 14th Street (US 69)

NE 14th Access-Related Crashes

SE 14th Access-Related Crashes

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

Operations: Capacity Is Higher On Better Managed Roads

Operations: Travel Speed Is Higher On Better Managed

Roads

Safety: Accident Rates Are Lower On Better Managed Roads

Safety: Iowa Case Studies

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

0

1

2

3

4

5

6

7

Crash Rate

(per MVMT)

Before

After

Safety: Crash Reduction By TypeAfter Access Management

For Iowa Case Studies

0 50 100 150 200 250

Rear End

Left/Broadside

Right Angle

Other

Total

Before

After

Access Management Treatments Help Pedestrians, Too

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

Conflict Points at Driveways

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

Separating Conflict Points

Facilitating Turning Movements: Important Strategies

Fewer, Better Driveways Are Better Than More DrivewaysWays 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

Steep Driveways Mean Slower Turns Out Or In

Dedicated Left And Right Turn Lanes

Channelization goes hand in hand withgood access management.

“Mixes Of Fixes”:Common Access Management

Treatments

Driveway consolidationCorner clearanceAlternative access ways (including internal site design)Continuous two-way left-turn lanes (TWLTL)Medians at intersectionsFull raised mediansWe often use combinations of these to manage access

Driveway Spacing And Corner Clearance

Green Book: functional area of the intersection

Too Many Driveways!

Good Corner Clearance: University Avenue: Windsor Heights

Alternative Access Ways

Alternative Access Ways

Alternative Access Ways: South Ames

Two-Way Left Turn Lane (TWLTL)

TWLTL: 3 And 5 Lane Cross-Sections

Median At Intersection

Median At Intersection

Full Raised Median

Raised Median: 100th Street Clive

Raised Medians Are Very Effective Safety Devices

Both of theseare a big improvementover anundivided 4lane

Access Management And Business Vitality:

Business owners often oppose access changes or restrictions—especially raised mediansBut measured impacts on businesses and land development are neutral to positiveIowa 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

Business Surveys Indicate Neutral-Positive Impact On Business Sales

Decreased

5%

Same

53%

Increased

33%

Uncertain

9%

86% of businessesalong newlyaccess managedroutes in Iowareported similar or increasedsales

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.

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

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

Access Management Can Be Implemented Many Ways

When designing new roadways, through good design and the acquisition of access rightsWhen rebuilding roadwaysWhen 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

Poor Land Use Planning Leads To Access Management Problems: Twin Cities, Minnesota

New city park blocks alternative New city park blocks alternative access road routeaccess road route

Warehouse where backageWarehouse where backageroad could beroad could be

Access Management Problems Happen In Rural Areas, Too

Areas of concern

And Land Use Decisions Can Make Problems Worse

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

Who Wins When Access Is Properly Managed?

MotoristsPedestriansCitizens/taxpayersBusinesspersons and developers, for the most part