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Handbook for Designing Roadways for the Aging Population

Chapter 1. How to Use this Handbook

Organization of the Handbook

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:

Figure 1. An image of the Handbook page describing treatments for Street Name Signs, with callout boxes to describe details of specific parts of the page (i.e., category and chapter number, design element number, treatment, and references and relationship codes).

Figure 1. Elements included for each Handbook treatment

Table 1. Definitions for the relationship codes between the recommendations and existing design guides or other manuals.
Code Definition
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:

For additional resources, visit the FHWA Office of Safety web site at http://safety.fhwa.dot.gov/.

Table 2. Abbreviations used for the references cited in the recommendation chapters.
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.

Time-Speed-Distance Table

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.

Table 3. Advance placement distances required to achieve desired preview times at designated operating speeds.
Preview Time (seconds) Operating Speed (mph)
30 35 40 45 50 55 60 65 70 75 80
2.5 110 128 147 165 183 202 220 238 257 275 293
3.0 132 154 176 198 220 242 264 286 308 330 352
3.5 154 180 205 231 257 282 308 334 359 385 411
4.0 176 205 235 264 293 323 352 381 411 440 469
4.5 198 231 264 297 330 363 396 429 462 495 528
5.0 220 257 293 330 367 403 440 477 513 550 587
5.5 242 282 323 363 403 444 484 524 565 605 645
6.0 264 308 352 396 440 484 528 572 616 660 704
6.5 286 334 381 429 477 524 572 620 667 715 763
7.0 308 359 411 462 513 565 616 667 719 770 822
7.5 330 385 440 495 550 605 660 715 770 825 880
8.0 352 411 469 528 587 645 704 763 822 880 939

Knowing When to Implement these Recommendations

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.

Step 1: Problem Identification [see Project Review Worksheet on page 7]

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:

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:

Step 2: Identification of Design Elements and Treatments [see worksheet on page 9]

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.

Project Review Worksheet

Project Title/ID: _______________________________________________________________

Person Completing Worksheet: __________________________________________________ Date: ________________________

Q1. "Is there a demonstrated crash problem with aging road users?" YES checkbox NO checkbox
Source(s) Date of Contact
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?" YES checkbox NO checkbox
Source(s) Date of Contact
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?" YES checkbox NO checkbox
Source(s) Date of Contact
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?" YES checkbox NO checkbox
Source(s) Date of Contact


Table 4. Example of Completed Design Elements and Treatments Worksheet.
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      

Step 3: Implementation Decision [see worksheet on page 10]

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.

Identification of Design Elements and Treatments Worksheet

Project Title/ID: _______________________________________________________________

Person Completing Worksheet: __________________________________________________ Date: ________________________

Identify design elements for which a treatment exists in the Handbook and the applicable treatments. Then, (a) describe differences between the treatment and standard practice, and (b) list benefits expected to result from implementing the Handbook.

Category Design Element Applicable Handbook Treatment Differs From Existing State or Local Practice? If YES…
NO YES Explain Difference Identify Expected Benefits


Implementation Worksheet

Project Title/ID: _______________________________________________________________

Person Completing Worksheet: __________________________________________________ Date: ________________________

List each treatment identified as a candidate for implementation. Document whether additional approval is needed (i.e., Environmental, Regulatory, etc.), and whether increased costs or other special considerations may affect implementation. Based on these considerations, decide whether implementation can be recommended, add your initials, and add supplemental comments as appropriate.

Treatment Implementation Considerations Implementation Recommended?
Added Costs? Added Approvals? Other




Page last modified on February 1, 2017
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