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Chapter 1. Introduction to the Desk Reference


This Desk Reference serves as a companion document to the Handbook for Designing Roadways for the Aging Population (the Handbook). It provides a quick reference to Part I of the Handbook and is ideal for use in the field or as an abbreviated information resource. While each design element from the Handbook is briefly described and illustrated in this desk reference, practitioners should refer to the corresponding section in the Handbook for more details and complete discussion.

This Desk Reference is organized in the following categories:

Chapter 2 – Intersections
Chapter 3 – Interchanges
Chapter 4 – Roadway Segments
Chapter 5 – Construction/Work Zones
Chapter 6 – Highway-Rail Grade Crossings

Within each chapter (category) is a list of the design elements that will be presented. For each design element, the Desk Reference illustrates the recommended treatments. After all of the numbered design elements are presented, then the "Promising Practice" treatments are provided. These are treatments that designers and engineers should consider, recognizing that they are currently being used by one or more agencies, and, although they have not been evaluated formally, are generally believed to benefit the aging population based on a subjective assessment by staff participating in the development of the Handbook.

Keep in mind that this Desk Reference is a condensed version of the corresponding material in the Handbook; practitioners should refer to the same treatment in the Handbook for additional details, examples, illustrations, and image sources.

Also note that the drawings included in this Desk Reference are for illustrative purposes only; they are not to scale and should not be used for design purposes.

Knowing When to Implement these Recommendations

Implementing the treatments in this Desk Reference will 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.

The engineering enhancements described in this document should benefit all road users. Special justification may be required for implementation of Handbook practices. To this end, below is a three-step procedure outlining responses plus brief written comments to support engineering judgment. Please refer to the Handbook for a set of optional worksheets for documenting each step. Step 1: Problem Identification [see Project Review Worksheet on page 7 of the Handbook]

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 work sheet that appears on page 7 of the Handbook, problem identification can be accomplished by answering 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:

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

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). See the Handbook for a more in-depth discussion of the identification process.

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

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.


Like the Handbook for Designing Roadways for the Aging Population (Handbook), this Desk Reference 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 the original 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.

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 Manual on Uniform Traffic Control Devices (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 Desk Reference are not always consistent with those prescribed in the MUTCD. When employing treatments included in this Desk Reference and 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 must request experimentation approval from the FHWA.

Handbook References – This Desk Reference contains references below each treatment that indicate where the rationale and supporting evidence for this treatment can be found. This includes references to those national design guides that practitioners often turn to for guidance on the use and implementation of the treatment.

Example page in the desk reference identifies where on each practice the reader can find the category, design element, treatment, figure, and reference to the full resource page in the Handbook. Each practice is also numbered consistently with the complete Handbook for easy reference.

Page last modified on December 29, 2015
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