A Guide for Reducing Collisions Involving Older Drivers

Introduction

The six major areas of the AASHTO Strategic Highway Safety Plan—Drivers, Vehicles, Special Users, Highways, Emergency Medical Services, and Management—are subdivided into 22 goals, or key emphasis areas, that impact highway safety. One of these goals addresses the reduction of crashes and fatalities involving older drivers. This implementation guide provides engineering, planning, education, and policy guidance to highway agencies that desire to better accommodate older drivers’ special needs. Older drivers represent a subset of the driving population that deserves special attention. Aging affects a variety of skills needed for safe driving. In particular, the aging population experiences deterioration in physical, perceptual, and cognitive skills:

• Reductions in strength, flexibility, and range of motion caused by arthritis or other conditions can negatively impact driving.

• Many visual functions—including static and dynamic visual acuity, contrast sensitivity, and glare sensitivity—deteriorate with age.

• Normative aging most often affects cognitive changes, such as working memory, selective attention, and processing speed. Many highway design and traffic control elements can be improved to better meet the aging population’s physical, perceptual, and cognitive needs. In addition, motor vehicle departments, highway safety offices, medical professionals, and others can collaborate to help older adults extend their safe driving years.

General Description of the Problem

The number of older drivers in the United States will double over the next 30 years (Exhibit I-1). By 2030, one in five Americans will be age 65 or older. As people age, a decline in sensory, cognitive, or physical functioning can make them less safe drivers, as well as more vulnerable to injury once in a crash. Yet older Americans depend on automobiles for meeting their transportation needs. The safety of older drivers can be measured several ways. On a licensed-driver basis, older adults are among the safest. The average annual number of crashes in the United States is 68 per 1,000 licensed drivers, while the corresponding rate for drivers 65 and older is only 37. The picture changes somewhat when crash rates are calculated on the basis of miles traveled. Using this measure of exposure, older adults are at increased crash risk. The real safety concern for the older driver arises when one also takes into consideration their increased likelihood of being injured or killed in a crash. Compared with an overall fatality rate of 2 per 1,000 crashes, persons ages 65–74 have a fatality rate of 3.2. For those 75–84, the rate is 5.3, and at 85 and above it climbs to 8.6. When the safety of older drivers is measured in terms of fatalities per licensed driver and fatalities per mile traveled, there is clearly cause for concern.

Objectives of the Emphasis Area

The objectives for better accommodating the special needs of older drivers are to • Plan for an aging population, • Improve the roadway and driving environment to better accommodate older drivers’ special needs, • Identify older drivers at increased risk of crashing and intervene, • Improve older adults’ driving competency, and • Reduce the risk of injury and death to older drivers and passengers involved in crashes. Exhibit I-2 lists the objectives and strategies designed to meet these objectives. Because the AASHTO Strategic Highway Safety Plan is geared toward low-cost, short-term safety improvements, the list of strategies presented in Exhibit I-2 consists more of low-cost, shortterm treatments than high-cost, long-term treatments. Many high-cost solutions should be considered at a project’s planning stages and are not typically used to treat high-accident locations. Examples of high-cost solutions that should become part of an agency’s design practice, rather than a “spot treatment,” include

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