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Handbook for Designing Roadways for the Aging Population

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June 2014


The proportion of the United States population age 65 and over will increase significantly in the coming decades. The effects of aging on people as drivers and pedestrians are highly individual. Challenges that may impact people as they age include declining vision, decreased flexibility and psychomotor performance, and changes in perceptual and cognitive performance. Design practices that explicitly recognize these changes will better serve this growing segment of the nation's population.

This Handbook for Designing Roadways for the Aging Population provides practitioners with a practical information source that links aging road user performance to highway design, operational, and traffic engineering features. This Handbook supplements existing standards and guidelines in the areas of highway geometry, operations, and traffic control devices.

The information in this Handbook should be of interest to highway designers, traffic engineers, and highway safety specialists involved in the design and operation of highway facilities. In addition, this Handbook will be of interest to researchers concerned with issues of aging road user safety and mobility.

The Handbook is also available online at http://safety.fhwa.dot.gov/older_users/#training.

Tony Furst
Associate Administrator for Safety
Federal Highway Administration


This document is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The U.S. Government assumes no liability for the use of the information contained in this document. This report does not constitute a standard, specification, or regulation.

The U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers' names appear in this report only because they are considered essential to the objective of the document.

Quality Assurance Statement

The Federal Highway Administration (FHWA) provides high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information.

FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement.

Technical Report Documentation Page

1. Report No.
2. Government Accession No. 3. Recipient's Catalog No.
4. Title and Subtitle
Handbook for Designing Roadways for the Aging Population
5. Report Date
June 2014
6. Performing Organization Code
7. Author(s)
Marcus Brewer, Debbie Murillo, Alan Pate

Authors of Previous Draft
David Harkey, Loren Staplin, Kathy Lococo, Raghavan Srinivasan, Jongdae Baek, Michael Daul, Hugh McGee, Michael Tantillo
8. Performing Organization Report No.
9. Performing Organization Name and Address
Texas A&M Transportation Institute
2935 Research Parkway
College Station, Texas 77845
505 King Avenue
Columbus, OH 43201

Performing Organization Name and Address for Previous Draft

University of North Carolina
Highway Safety Research Center
730 ML King Blvd, CB #3430
Chapel Hill, NC 27599

Vanasse Hangen Brustlin, Inc.
8300 Boone Blvd., Suite 700
Vienna, VA 22182
1722 Sumneytown Pike
Box 328
Kulpsville, PA 19443
10. Work Unit No. (TRAIS)
11. Contract or Grant No.
DTFH61-12-D-00046, TO T-13005
Contract or Grant No. for Previous Draft
DTFH61-05-D-00024, TO T-10-002
12. Sponsoring Agency Name and Address
Federal Highway Administration
Office of Safety
1200 New Jersey Ave. S.E.
Washington, DC 20590-9898
13. Type of Report and Period Covered
Final Report
14. Sponsoring Agency Code
15. Supplementary Notes
Government Task Manager (GTM): Rebecca Crowe
16. Abstract

The original Older Driver Highway Design Handbook was published by FHWA in 1998 (FHWA-RD-97-135). The 2nd edition, titled Highway Design Handbook for Older Drivers and Pedestrians (FHWA-RD-01-103) was published in 2001. This 3rd edition, under a new title, incorporates new research findings and treatments to improve the safety of the transportation system for the aging population.

The Handbook is divided into three sections. The first section explains how to use the Handbook to select treatments to address problems for aging drivers and pedestrians. The second section includes treatments for 51 proven and promising traffic control and design elements distributed among five categories: Intersections, Interchanges, Roadway Segments, Construction/Work Zones, and Highway-Rail Grade Crossings. The final section of the Handbook includes the rationale and supporting evidence for the treatments.

A website including all of the content of the Handbook is available at http://safety.fhwa.dot.gov/older_users/#training.

17. Key Words
Safety, Highway Design, Traffic Operations, Driver Age, Driver Performance, Pedestrian, Human Factors, Vision, Attention, Perception, Cognition, Memory, Physical Ability, Risk Perception, Hazard Perception
18. Distribution Statement
No restrictions.
19. Security Classif.
(of this report)

20. Security Classif.
(of this page)

21. No. of Pages
22. Price

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized



The increasing numbers and percentages of aging persons using our nation's streets and highways in the decades ahead will pose many challenges to transportation engineers who focus on safety and operational efficiency. According to the Administration on Aging, the 65-and-older age group, which numbered 39.6 million in the United States in 2009, will grow to more than 55 million in 2020. By 2030, there will be approximately 72.1 million aging persons, accounting for roughly one-fifth of the population of driving age in this country. In effect, for many aspects of road planning and design, the "design driver" and the "design pedestrian" of the early 21st century will likely be 65 or over.

There are important consequences of these changing demographics, and life for aging persons depends to an extraordinary degree on remaining independent. Independence requires mobility. In our society the overwhelming choice of mobility options is the personal automobile. Other mobility options that may be utilized include public transit and walking. This means that there will be a steadily increasing proportion of drivers and pedestrians who experience declining vision; slowed decision-making and reaction times; exaggerated difficulty when dividing attention between traffic demands and other important sources of information; and reductions in strength, flexibility, and general fitness.

In a proactive response to this pending surge in aging road users, the Federal Highway Administration (FHWA) published the Older Driver Highway Design Handbook in 1998. The 1998 Handbook provided highway designers and engineers with the first practical information source linking age-related declines in functional capabilities to enhanced design, operational, and traffic engineering treatments, keyed to specific roadway features. Experience with these enhanced treatments, including extensive feedback from local and State-level practitioners, led to the release of the Highway Design Handbook for Older Drivers and Pedestrians in 2001. Now, a third edition of this resource has been prepared, under a new title, which incorporates new research, expands the range of applications covered by the Handbook, and introduces format changes—including a webbased version—that will facilitate access and use by engineering professionals to improve our streets and highways in the years ahead.

Part I of this Handbook retains its focus on five broad categories of roadway features, each containing a number of specific design elements for which guidance is presented. The top priority is intersections, reflecting aging drivers' most serious and enduring crash problem area, as well as the greatest exposure to risk for pedestrians. Next, welldocumented difficulties with merging/weaving and lane changing maneuvers focus attention on interchanges. Roadway segments, with an emphasis on curves and passing zones, plus highway construction/work zones, are included due to heightened tracking (steering) demands that may increase a driver's workload along with an increased potential for unexpected events that require a rapid response. Finally, highway-rail grade crossings merit consideration as sites where conflicts are rare, and thus unexpected, and where problems of detection (with passive controls) may be exaggerated due to sensory losses with advancing age.

The treatments presented in Part I are followed by a more lengthy section, Part II, presenting the rationale and supporting evidence. Within each of these two major Handbook sections, material is organized in terms of five subsections, corresponding to the categories of roadway features noted above. Preceding the treatments, a chapter titled "How To Use This Handbook" explains codes used throughout the document to cross-reference the Manual on Uniform Traffic Control Devices (MUTCD), A Policy on Geometric Design of Highways and Streets (the Green Book) and other manuals and guides. In addition, a guide for interpreting graphics used in the Handbook and a table for translating speeds and distances into "preview times" for driver decision and response selection are presented; and, a structured approach to help engineering professionals decide when to implement Handbook treatments is described. A supplementary discussion about how to determine the visibility of roadway elements is appended to this edition of the Handbook.The Handbook concludes with a glossary providing definitions of selected terms and a reference list.

Most of the treatments in this Handbook are based on supporting evidence drawn from a comprehensive review of field and laboratory research addressing human factors and highway safety. The supporting information presented in Part II represents the latest relevant information and data available to the authors at the time the document was assembled. Some research findings have been carried forward from previous Handbooks, while other findings are new since the release of the 2001 Handbook. A number of additional treatments were considered but ultimately dropped or deferred because of gaps or deficiencies in the supporting studies. This edition also includes some "Promising Practices"—treatments that are being used by one or more agencies, which although they have not been evaluated formally, are generally believed to benefit the aging population of roadway users based on subjective assessment by the staff participating in the development of this Handbook. This conservative approach also dictated that the Handbook's treatments relate to the demonstrated performance deficits of normally aging drivers and pedestrians. It deserves mention that diminished capabilities that result from the onset of Alzheimer's disease and related dementias, which may afflict over 10 percent of those age 65 and older and over 40 percent of those age 85 and older, are not explicitly targeted in these guidelines. Neither are the compromises in performance that are associated with drowsiness, fatigue or distraction.

This resource can be applied preemptively to enhance safety wherever there are aging road users in a given jurisdiction, or it may be employed primarily as a "problem solver" at crash sites. The implementation of these treatments will translate into real gains in safety and mobility for our nation's aging citizens, and indeed for all users of our surface transportation system. Readers of this Handbook must note, however, that the treatments presented in this Handbook do not constitute a new standard of required practice. The final decision about when and where to apply the treatments presented in this Handbook remains at the discretion of State and local design and engineering professionals.


The quality and usefulness of the Handbook for Designing Roadways for the Aging Population is a direct result of the many highway engineering practitioners and researchers who provided their comments and suggestions to the authors of this edition of the Handbook, as well as the previous two editions. The authors wish to acknowledge the following individuals for their assistance and support in making this third edition a success:

The authors would also like to acknowledge Charlie Zegeer, Laura Sandt, and Carl Sundstrom of the FHWA Pedestrian and Bicycle Information Center for their input to the pedestrian treatments included in the Handbook.

Table of Contents

Part I. Treatments

Part II. Rationale and Supporting Evidence

Abbreviations and Acronyms

American Automobile Association Foundation for Traffic Safety
annual average daily traffic
American Association of State and Highway Transportation Officials
American Society for Testing and Materials
American Traffic Safety Services Association
Commission Internationale de l'Eclairage
complete interchange lighting
changeable message sign
concrete safety-shaped barrier
diverge steering
decision sight distance
Fatality Analysis Reporting System
Federal Highway Administration
gap search and acceptance
initial acceleration
Insurance Institute for Highway Safety
intersection sight distance
in-service brightness level
Intermodal Surface Transportation Efficiency Act
Institute of Transportation Engineers
legibility index
leading pedestrian interval
measure of effectiveness
minimum required visibility distance
merge steering control
Manual on Uniform Traffic Control Devices for Streets and Highways
National Cooperative Highway Research Program
National Highway Traffic Safety Administration
no turn on red
National Transportation Safety Board
partial interchange lighting
post-mounted delineator
perception-reaction time
reaction time
raised pavement markers
right turn on red
steering control
speed-change lane
stopping sight distance
small target visibility
single unit (truck)
traffic control device
Transportation Research Board
transient visual adaptation
two-way, left-turn lane
visual clear
Page last modified on October 15, 2014.
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