U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
The Handbook consists of two parts. Part I includes recommended treatments for 33 traffic control or geometric design elements divided among five categories. The five categories of treatment are as follows:
These treatments are recommended because they have been shown through research to be a benefit to the aging road user. In addition, 18 "Promising Practice" treatments are included. These are treatments being utilized by transportation agencies that should benefit aging road users as determined by a subjective assessment by staff participating on the development of this Handbook. Current trends indicate these practices have a positive impact on aging road user safety. These promising treatments are placed at the end of each category to which they apply.
Part II includes the rationale and supporting evidence for each of the treatments. This part of the Handbook is also divided into these same five categories.
The treatments for each design element are presented as shown in Figure 1 and consist of the following components:
Category — At the top of each page is a header showing the category of treatment (i.e., Intersections, Interchanges, Roadway Segments, Construction Work Zones and Highway-Rail Grade Crossings).
Design Element — Each element has a unique number for quick reference to the Table of Contents.
Treatments — Each treatment within a design element is clearly identified by a unique letter, followed by a recommendation on how that treatment should be used.
Figure(s) — Many of the concepts described in the treatments are illustrated in figures—as photographs, figures extracted from the MUTCD or other publications, or as drawings. The drawings are for illustrative purposes only; they are not to scale and should not be used for design purposes. It is important to note that the lettering styles, arrows and symbols used in this Handbook are not always consistent with those prescribed in the MUTCD. When employing treatments included in this Handbook, only MUTCD-approved lettering styles, arrows and symbols should be used. Additionally, any highway agency wishing to implement a treatment that has not been included in the most recent edition of the MUTCD, and thus denoted by a relationship code of "5"(see Table 1), must request experimentation approval from the FHWA.
References and Relationship Codes — References placed below each treatment indicate its relationship (by a numeric relationship code) to the design guides most frequently referenced by practitioners, as determined by the Handbook authors. A legend is provided at the bottom of each treatment page to remind users (in an abbreviated format) of the meaning of the numerical values. The complete definitions for these relationship codes are provided in Table 1.
|1||Handbook treatment selects the most conservative design value among present options in the standard manual/guideline. (Example: Using a larger sign size identified as an "option"in the MUTCD).|
|2||Handbook treatment indicates the preferred design value where a discrepancy exists among two or more manuals/guidelines. (Example: Limit skew to 75° as per TEH instead of 60° as per Green Book).|
|3||Handbook treatment extends a current practice to a new application or operation. (Example: Use of fluorescent sheeting on wrong-way control signing, for increased conspicuity).|
|4||Handbook treatment advances a specific design value or concept where only general guidance now exists, or provides more detailed or more stringent design criteria than are currently specified. (Example: It is recommended that an advance street-name plaque be used wherever an advance intersection warning sign is installed. The use of this supplemental plaque is an option per engineering judgment in the 2009 MUTCD.)|
|5||Handbook treatment is permissible at this time only in accordance with the provisions of MUTCD Section 1A.10, Interpretations, Experimentations, Changes and Interim Approvals. These treatments represent advances in technology which research indicates will result in improved safety and efficiency of operations. (Example: It is recommended that the Roundabout Circulation Plaque (R6-5P) be placed immediately below the R1-2 Yield sign on both sides of the road at each entrance to a roundabout.)|
The design guides, manuals, and other resources referenced by the relationship codes in the treatments and throughout the Handbook are shown in Table 2. The most current published edition of each guide was consulted in the preparation of the Handbook, with the exceptions as noted. The latest version of the MUTCD can be accessed at http://mutcd.fhwa.dot.gov.
In addition to the design guides shown in Table 2, there are a number of other resources and supporting tools available to assist in improving the roadway environment for aging (and all) road users. Some key resources include:
Interactive Highway Safety Design Model (IHSDM): A suite of software analysis tools for evaluating safety and operational effects of geometric design decisions on two-lane rural highways (https://www.fhwa.dot.gov/research/tfhrc/projects/safety/comprehensive/ihsdm/).
Highway Safety Manual (HSM), 1st Edition, Volumes 1, 2 and 3, 2010: This resource provides safety knowledge and tools to facilitate improved decision-making based on safety performance (http://www.highwaysafetymanual.org).
SafetyAnalyst: Analytical tools for use in the decision-making process to identify and manage a system-wide program of site-specific improvements to enhance highway safety by cost-effective means (http://www.safetyanalyst.org/).
Human Factors Guidelines for Road Systems, NCHRP Report 600: This report is designed to help non-experts in human factors to consider more effectively the roadway user's capabilities and limitations in the design and operation of highway facilities (http://www.trb.org/Main/Blurbs/167909.aspx).
NCHRP Report 500: Guidance for Implementation of the AASHTO Strategic Highway Safety Plan: A series of guides to assist transportation agencies in reducing specific types of crashes in targeted emphasis areas outlined in the AASHTO Strategic Highway Safety Plan (http://www.trb.org/main/blurbs/152868.aspx).
Pedestrian Road Safety Audit Guidelines and Prompt Lists: A guide for conducting formal safety examinations of future roadway projects or in-service facilities with a focus on identifying and addressing pedestrian safety concerns (http://www.walkinginfo.org/data/library/details.cfm?id=3955). Similarly, a guide is available for conducting more general road safety audits (http://safety.fhwa.dot.gov/rsa/).
AASHTO Guide for the Planning, Design, and Operation of Pedestrian Facilities: Guidelines are included for the construction and design of sidewalks, street crossings, and many aspects of pedestrian trails. The document is available for purchase at https://bookstore.transportation.org/.
PEDSAFE: Pedestrian Safety Guide and Countermeasure Selection System: This interactive system is intended to help practitioners choose the most appropriate engineering, education, and enforcement countermeasures to address pedestrian safety and mobility issues (www.walkinginfo.org/pedsafe).
For additional resources, visit the FHWA Office of Safety web site at http://safety.fhwa.dot.gov/.
|Abbreviation Key||Reference Citation|
|Green Book||A Policy on Geometric Design of Highways and Streets (Green Book). American Association of State Highway and Transportation Officials, 2011.|
|HCM||Highway Capacity Manual. Transportation Research Board, 2010.|
|MUTCD||Manual on Uniform Traffic Control Devices for Streets and Highways. (2009 Edition). Federal Highway Administration, 2009.|
|NCHRP 279||Intersection Channelization Design Guide, (NCHRP Report 279). National Cooperative Highway Research Program, 1985.|
|NCHRP 500-9||Guidance for Implementation of the AASHTO Strategic Highway Safety Plan, Volume 9: A Guide for Reducing Collisions Involving Older Drivers, (NCHRP Report 500, Volume 9). National Cooperative Highway Research Program, 2004.|
|NCHRP 672||NCHRP Report 672, Roundabouts: An Informational Guide(Second edition).|
|NCHRP 674||Crossing Solutions at Roundabouts and Channelized Turn Lanes for Pedestrians with Vision Disabilities, (NCHRP Report 674). National Cooperative Highway Research Program, 2010.|
|RLH||FHWA Lighting Handbook, Federal Highway Administration, 2012.|
|RRX||Railroad-Highway Grade Crossing Handbook, Revised 2nd Edition. Federal Highway Administration, 2007.|
|TEH||Traffic Engineering Handbook, 5th Edition. Institute of Transportation Engineers, 2009.|
A number of treatments presented in the Handbook identify the placement of a device or treatment in terms of the preview time that should be provided to the driver for its application. These values are typically expressed in seconds, such that the recommended placement of the device or treatment depends upon the speed at which traffic is moving. To facilitate application of Handbook treatments of this nature, Table 3 provides the advance placement distance needed to achieve a desired preview time at a particular operating speed.
|Preview Time (seconds)||Operating Speed (mph)|
Implementation of the treatments in this Handbook provide benefits for design challenges that disproportionately affect aging road users due to changes in functional ability experienced with normal aging. These may be most urgently needed where a crash problem with aging drivers or pedestrians has already been demonstrated; however, the greater benefit arguably lies in designing safer new roads and identifying and modifying problems with existing roads before statistics reveal a crash problem. Not only does this practice minimize the risk and severity of crashes, it minimizes the need for remedial works after construction, thus reducing the whole-life cost of projects. This is the central premise of the road safety audit process supported by FHWA and it holds the key for applying the Handbook treatments as well.
The engineering enhancements described in this document should benefit all road users. Special justification may be required for implementation of Handbook practices. This section was developed to support engineering judgment in this regard. It suggests a three-step procedure using checklist responses plus brief written comments, as explained below. A set of optional worksheets for documenting each step is also provided.
During the planning stage for each project, practitioners are asked to determine whether a problem with the safe use of the facility by aging road users currently exists or may reasonably be expected based on current and projected use patterns. Using the first worksheet that follows this discussion, problem identification can be accomplished by checking YES or NO to the following four questions:
Q1. "Is there a demonstrated crash problem with aging road users?"
Q2. "Has any aspect of design or operations at the project location been associated with complaints to local, municipal, or county-level officials from aging road users or are you aware of a potential safety concern for aging road users at this location, either through observation, agency documentation, or engineering judgment?"
Q3. "Is this project located on a direct link to a travel origin or destination for which, in the judgment of local planning/zoning authorities or other local officials, aging persons constitute a significant proportion of current users?"
Q4. "Is the project located in a census tract or zip code designation that has experienced an increase in the proportion of (non-institutionalized) residents age 65 and older, for the most recent period in which the population was sampled?"
To answer these questions, practitioners will need to obtain reliable crash data from the appropriate division or bureau of their departments of transportation. At least the three most recent years for which data are available should be examined, and the data should be sorted by age, at a minimum. Sources of information outside of the State DOT also may be required to answer the problem identification questions. Potential sources include, but are not limited to:
Local government officials/Board of Supervisors/city council representatives.
Local and State police.
The (State) Department of Aging and/or county Area Agency on Aging.
The (State) Department of Health and Human Services and Department of Public Welfare.
The regional planning commission.
For each project where a practitioner has answered YES to one or more of the problem identification questions in Step 1, the next step is consider all categories (i.e., intersection, interchanges, roadway segments, construction/work zones, and highway-rail grade crossings) on the facility. Then, for each category, consider each design element and treatment that could be applied. For each one, the engineer should indicate whether the recommended practice differs from standard State or local practices, and if yes, what additional benefits are expected to result from implementing the applicable Handbook treatment(s). One possible example of how such worksheet entries could be made is shown in Table 4.
|Category||Design Element||Applicable Handbook Treatment||Differs From Existing State or Local Practice?||If YES…|
|NO||YES||Explain Difference||Identify Expected Benefits|
|Intersections||1. Intersecting Angle (Skew)||(1C) Skewed Signalized Intersection||✓||According to MUTCD warrants, there is "adequat" sight distance and fewer than 3 RTOR crashes annually on approach.||Should reduce the difficulty for aging drivers to check for approaching traffic, and also reduce aggressive behavior of following drivers who don't accept an aging driver's decision not to turn on red.|
|Intersections||10. Street-Name Signs||(10A) Letter Heights and Sign Border||✓|
|Intersections||16. Roundabouts||(16C) Splitter Islands||✓|
|Intersections||24. Flashing Yellow Arrow||(Promising Practice for permissive left turns)||✓||Current practice uses a green ball for permissive left turns.||Should improve the ability of aging drivers to correctly recognize when permissive left turns are allowed.|
|Construction/ Work Zones||43. Signing and Advance Warning||(43C) Sign Sheeting||✓|
To begin Step 3, each Handbook treatment identified as a candidate for implementation in Step 2 should be properly referenced [e.g., 5D(1)]. Next, any factors relating to increased costs (for an enhanced treatment), added approvals that may be needed, or any other special considerations that impact implementation may be noted in separate columns on the worksheet. The final step is then to proceed to an implementation decision. This is recorded as a judgment by the engineer as to whether implementation of the candidate countermeasure is recommended. The engineer's judgment is indicated by a check in the space next to YES or NO in the last column on the worksheet, accompanied by his/her initials for verification. Additional comments should be entered as deemed appropriate.