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2020 TRB Annual Meeting

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Join us at the 2020 TRB Annual Meeting in Washington, DC January 12-16

(Note, on Dec 10 TRB assigned a new comittee structure. Access Management Committee (ACP60) is now under the Operations Section (ACP00).

Sunday  1:30 PM-4:30 PM

Workshop 1074

Applying Your Multimodal Access Management Toolbox
Marc Butorac, Kittelson & Associates, Inc. (KAI), presiding
Operations and Traffic Management, Design
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Monday  10:15 AM-12:00 PM

Poster Session 1223

Access Management 2020
Operations and Traffic Management 
(see descriptions at end)

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Monday  7:30 PM-9:30 PM

Intersections, AHB65(1), Joint Subcommittee of AHB65, AFB10, AHB70, ANB20
Gil Chlewicki, Advanced Transportation Solutions, LLC, presiding
Jonathan Soika, VHB, presiding
Design, Operations and Traffic Management, Safety and Human Factors
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Tuesday  12:00 PM-1:30 PM

National Conference on Access Management Subcommittee, AHB70(1)
Lionel Lucien, Massachusetts Department of Transportation, presiding
By Invitation
Operations and Traffic Management

Tuesday  1:30 PM-3:15 PM

Access Management Research Subcommittee, AHB70(2)
Christopher Cunningham, North Carolina State University, presiding
Eric Fitzsimmons, Kansas State University, presiding
Operations and Traffic Management
More Details

Tuesday  3:45 PM-5:30 PM

Access Management Outreach Subcommittee, AHB70(3)
Kristine Connolly, Kittelson & Associates, Inc. (KAI), presiding
Joy Davis, Institute for Transportation Research and Education, presiding
Operations and Traffic Management
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Wednesday  8:00 AM-12:00 PM

Access Management Committee
Grant Schultz, Brigham Young University, presiding
Operations and Traffic Management
More Details


Poster session 1213Monday 10:15 AM-12:00 PM

Effect of Driveway Land-Use Type on Safety Performance for Two-Lane Rural State Highways and County Roads

Meghna Chakraborty, Michigan State University
Timothy Gates, Michigan State University

Rural roads are a critical component of transportation network in the United States, including Michigan, where county roads comprise of a majority of the state’s roadway mileage. The rates of fatal crashes on rural highways are substantially higher than that on urban roads. Previous research has investigated the safety impacts of driveway density, but little has captured the effects of various driveway land-use categories on rural roadway safety performance, particularly for county roadways. This study analyzes the safety impacts of various classifications of driveway land utilization on rural two-lane state and county roads in Michigan. Non-animal segment crashes from 2011 to 2015 were analyzed along with roadway data for greater than 5,556 miles of state highways and 5,890 miles of paved county segments from across Michigan. To account for the unobserved heterogeneity associated with varied county design standards, mixed-effects negative binomial regression models with a county-specific random effect were utilized. Separate models were developed for state highways and paved county roads. The results indicated that commercial driveways possess a stronger effect on crash occurrence than other driveway land use types, including residential and industrial driveways. The effect of driveway density on crash frequency was also found to be stronger on state highways compared to the county roads. This study contributes to the limited body of knowledge regarding the relationship between traffic safety and driveway land use for rural roadway segments, particularly for county roads, which typically possess design and travel characteristics that are considerably different from those of state highways. 

Safety Performance of Rural Offset T Intersections

Anthony Ingle, Michigan State University
Timothy Gates, Michigan State University

Offset T intersections represent a special case where two three-leg intersections adjoin the major road from opposite directions within a minimal separation distance. The operational and safety characteristics of these two intersections are inter-dependent. In rural areas, the preponderance of offset T intersections occur where section line minor roads intersect township line roads and primary arterials often at nearly perpendicular angles. Safety performance functions are developed using negative binomial models to predict the crash frequency among a sample of 113 offset T intersections and 112 four-leg cross intersections along rural Michigan highways. Through a cross sectional analysis, several crash modification factors for the conversion of an offset T intersection to a four-leg cross intersection are determined. A reduction of in total crash frequency of up to 34 percent is expected when converting and offset T intersection into a four-leg intersection. Fatal and injury crash frequencies are expected to reduce by 24 percent, while property damage only crash frequencies are expected to reduce by 16 percent. For low minor road traffic volumes (less than 15 percent of the total intersection entering traffic) converting an offset T intersection to a four-leg intersection can reduce angle crashes by 51 percent. However, offset T intersections are much more effective at reducing angle crashes for moderate to high minor road traffic volumes. Rear-end crash types can be reduced by 46 percent by converting an offset T intersection to a four-leg intersection. This study will help safety engineers to prioritize the improvement of rural un-signalized intersections. 

Poster Session 1221 10:15 AM-12:00 PM

Driveway Access Spacing Considerations for Rural Highways with High Truck Volumes

Marcus Brewer, Texas A&M Transportation Institute
Kay Fitzpatrick, Texas A&M Transportation Institute
James Cline, Texas A&M Transportation Institute

Increased traffic and heavy truck percentages associated with energy exploration in west Texas have placed unprecedented demands on the region’s highway network as well as driveway access to and from that network. Access management principles have proven to be effective in improving operations and safety in numerous locations, but many of those locations have been in urban or suburban locations where land uses and traffic patterns are different from those typically found in rural west Texas, so guidelines for driveway spacing and other access management treatments in rural, high-speed areas are not as commonplace. This paper describes the study of a corridor with high volumes, high truck percentages, high speeds, high turning volumes, and high demand for access. The study team reviewed the applicable guidelines and policies for driveway spacing in Texas, as well as relevant findings from other guidelines and research, to develop a set of recommended driveway spacing values for cars and for trucks on high-speed rural roads. 


Poster Session 1691 Wednesday 8:00 AM - 9:45 AM

Safety Performance of Autonomous Vehicles on an Urban Arterial in Proximity of a Driveway

Seyedeh Maryam Mousavi, Texas A&M University, College Station
Dominique Lord, Texas A&M University, College Station
Seyed Reza Mousavi, Shiraz University
Maryam Shirinzad, Texas A&M University, College Station
Maryam Shirinzad, Texas A&M University, College Station

Urban traffic network has been growing as an integral part of cities. Urban arterials, as the backbone of the urban traffic network, are characterized by closely spaces driveways and carry a high traffic volume per day. The literature consistently reported that there is a positive relationship between driveway density and crash rate. Therefore, managing driveways, which usually work as three-legged unsignalized intersections, located along urban arterials is crucial, especially under high traffic demand, to improve both safety and operation. However, due to the cost and space limitation, conventional methods are impractical and, therefore, new solutions should be implemented. Autonomous Vehicles (AVs), as a multidisciplinary technology, have been the focus as a replacement for human-driven vehicles to improve both traffic safety and operation. In this study, the effect of AVs on the safety of an urban arterial in the proximity of an unsignalized intersection was evaluated. A microsimulation model was used to develop an urban network with an unsignalized access point under various traffic congestion levels for both conventional vehicles and AVs. Afterward, the frequency and distribution of the conflicts for conventional vehicles and AVs were compared. The results indicated that AVs can enhance safety significantly compared to the conventional vehicles in proximity of an access point, especially under congested traffic situations. However, providing an exclusive lane on the arterial for the driveway vehicles to merge to the arterial promotes safety and operation of the network.



Access Management: Fundamental Principles and Application

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NHI offers two courses to learn about Access Management. A comprehensive three-day approach to learning techniques and impacts of Access Management, and a shorter one day overview to help those who want a basic understanding.

Access Management: Fundamental Principles, Application and Computation

PROGRAM AREA: Design and Traffic Operations



This course is designed to provide those who plan, operate, design, construct, or administer surface transportation or land use systems with a basic understanding of the concepts and tools available to them, the benefits of successful access management, and the costs of unsuccessful access management. 

This three-day course provides more in-depth content targeted for technical professionals. This course is intended to attract participants beyond traditional state and local agency technical staff, including: planners, engineers, permit specialists, legal counsel, and project managers associated with transportation planning, operations, design, maintenance, and development review. The third day of this three-day class is designed to provide additional and more advanced instruction to participants than the FHWA-NHI133078 (two-day) course and is for those who desire to deepen their understanding of access management through more computationally-driven applications of the course materials.


Upon completion of the course, participants will be able to:

  • Determine the impacts of signalized and unsignalized access connections on a given corridor in terms of safety, capacity, and business market area
  • Describe optimum connectivity for a given land use
  • Calculate needed turn lane lengths, given a set of data
  • Describe the interactions of access management treatments with both motorized and non-motorized users
  • Select appropriate median access management techniques for a given application
  • Select appropriate margin access management techniques for a given application


Technical professionals who are responsible for the engineering and planning applications necessary to support the development and administration of policies, planning, and design of transportation facilities and programs regarding access management.

This two-day NHI course is designed to provide those who plan, operate, design, construct, or administer surface transportation or land use systems with a basic understanding of access management concepts and tools (e.g., permits, governance, practicality) available to them, the benefits of successful access management, and the costs, consequences, and even potential liabilities of unsuccessful access management.



Upon completion of the course, participants will be able to:

  • Define key concepts of access management and understand the symbiotic relationship of driveways, local streets, collectors, arterials and highways.
  • List the benefits of good access management. Understand the consequences of poor access management.
  • State the impacts of either favoring access or through traffic on the safety, operations, and sustainability of surface transportation systems for all users.
  • Explain the importance of access management to complete streets and transportation (all modes) systems.
  • Describe access-related challenges as they pertain to public rights-of-way and private property.
  • Choose access management techniques or combinations of techniques that meet intended precepts to move traffic, or provide access, with attention to enhancing safety and operations for all users.
  • Identify and address legal, political, and jurisdictional challenges to implementation of access management.


This course is intended for both technical and non-technical professionals working in, or having a strong interest in, transportation or land use planning, operations, design, maintenance, and development review in the public and private sectors.

If you have questions about this NHI training, please contact NHI at or 877.558.6873.

An additional 1 day course is also available 


Access Management: The Musical

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Access Management: The Musical

12th AM CONFERENCE Session – Access Management “The Musical”

Thanks to the Brew City Harmony Barbershop quartet for bringing "Access Management: The Musical" to the 12th National Conference on Access Management!

Watch the Video

Listen to the MP3

Read the lyrics



Frank Broen


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State Access Management Library

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Many states implement access management, although approaches will vary in scope and style. This list will allow for identifying and cross-sharing of best practices among states and practitioners. 

State Websites:


Permits & Operations – includes AM Manual



List of state laws




Access Driveway Permits

Driveway Rules (PDF)



Corridor Management Strategies (PDF)


Colorado (extensive)


Highway Design Manual


Delaware (extensive)
Entrance Manual


Florida (extensive)


Georgia (extensive)






What is Access Management?



Chapter 35 discusses the general concepts of access management


Indiana (extensive)
Final Access Management Guide


Iowa (extensive)
Iowa Primary Highway Access Management Policy


Kansas (extensive)



2004 report


Permit forms


Maine (extensive)


Maryland (many projects listed)

Manual, residential info.




Michigan (extensive, but no online manual),1607,7-151-9621_11041_29705---,00.html


Minnesota (extensive - go in "continued")


 Access Management Manual (PDF)


Missouri (extensive)



Brochure (PDF)

2002 policy


2002 manual



1999 manual


New Hampshire

Citizen’s Guide

Access Management Manual

New Jersey (extensive)


New Mexico (extensive)


New York (extensive)

North Carolina (many links)
Policy on Street and Driveway Access

North Dakota

see Chapter 3 – Roadway Design


Ohio (extensive)




Oregon (extensive)


Pennsylvania (extensive)
List of Permits

Access Management Model Ordinances for Pennsylvania Barriers to AM (PDF)

State of the Practice for Access Management (PDF)

Best Practices in Access Management (PDF)

Legislative and Policy Barriers to Access Management (PDF)

Land Use and Transportation Planning


Rhode Island

2005  Manual (PDF)


South Carolina

"Encroachment" permit application

Strategic Corridor Network Plan


South Dakota (extensive)




Texas  (extensive)


Utah  (extensive),V:675,


Vermont (extensive)




Washington (extensive)

Access and Hearings
has links to 3 pdfs

Access Permit Guidelines


West Virginia

Driveway Manual (PDF)

Corridor Studies: One-Size Does Not Fit All


Permit forms



WYDOT Access Manual (PDF)