May/June 2006 · Vol. 69 · No. 6
May/June 2006
Road Users Can Grow Old Gracefully—With Some Help
by Lisa Phillips, Gabriel Rousseau, and Joanne Schwartzberg, MD
When making recommendations on infrastructure design, FHWA considers changes in the abilities of senior motorists and pedestrians.
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Older motorists like this woman will benefit from highway improvements such as improved intersections and larger street signs. Photos: NHTSA |
By the year 2030, one in five Americans will be age 65
or older. The fastest
growing segment of the U.S. population is people more than 85 years of age. Every year, a growing portion of those who use the
Nation's roads and sidewalks are older adults.
As
people age, their abilities change. Some things, such as vocabulary and
knowledge, can increase throughout a person's lifespan, but other abilities,
such as vision, typically decline. Unfortunately, a large vocabulary does not
help a motorist drive across town as much as acute visual
ability does.
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Source: NHTSA Traffic Safety Facts 2004. |
The
challenge for the transportation industry is to maximize safe mobility options
for the older population while maintaining safety for all road users. "Understanding how the most common age-related
abilities decline can help the transportation community design infrastructure
to minimize the negative consequences of those declines," says Elizabeth Alicandri, director of the Federal Highway Administration's
(FHWA) Office of Safety Programs.
Challenges
Associated With Decreased Abilities
The aging process is specific
to each individual, although certain chronic medical conditions and associated
functional limitations that can affect driving may become more prevalent with
age. A particular medical diagnosis alone, however, does not guarantee
functional decline in ability. Because of the diversity in how age affects
different individuals, many older adults will continue to drive safely well into their retirement years.
"Many assume that all drivers become dangerous as they
age," says Dennis Utter, director of the Office of
Traffic Records and Analysis, National
Center for Statistics and Analysis. "This
possibility is a growing public health concern. On the one hand, the average
annual driver involvement rate in police-reported motor vehicle crashes in the
United States is 55
per 1,000 licensed drivers, while the corresponding rate for drivers aged 65
and older is only 28 per 1,000."
If measured by miles
traveled, however, older adults may be at increased crash risk. According to National
Highway Traffic Safety Administration (NHTSA) data
from the mid-1990s, drivers aged
85 and older have about the same fatality rate per mile driven as 20-
to 24-year-olds
The
primary issue is the potential for increased deaths of both older drivers and
older pedestrians. Older drivers are less a threat to other road users than
they are to themselves. However, crashes lead to death more frequently for
older people, who may be frail due to chronic medical conditions and may take much
longer to recover from severe injuries.
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Source: Administration on Aging. |
Moreover,
travel options other than driving are extremely limited in many areas of the
United States. Driving remains the preferred mode, particularly where reliable
and affordable alternatives do not exist. Driving can help maintain the
benefits of personal mobility for seniors, both physically and socially. Loss
of personal mobility, on the other hand, can lead to cascading negative effects
such as depression, which can then accelerate physical and mental deterioration,
leading to earlier hospitalizations and nursing home admissions. For a majority
of older Americans, driving is the only "personal" mobility option they have ever
known, and they have come to expect to maintain the privilege indefinitely.
In many urban areas, walking can be an enjoyable and
healthful travel option for older adults. In fact, after driving, walking is
the second most used travel mode by older people. Walking often is not an
option, however, for both real and perceived reasons. Older pedestrians are
more vulnerable to death or serious injury when struck by motor vehicles, and
older adults sometimes cite personal security as a reason for not walking.
Given
the necessity of driving and walking for many older adults, reviewing facts
about their habits can shed light on the challenges. Seniors actually practice
many safe driving behaviors. They are more likely to wear seatbelts and obey the speed limit. They are less likely to
engage in some of the risky behaviors more common to younger drivers, such as
talking on a cell phone or drinking and driving. Once they become aware of
changes in their physical abilities, older drivers often begin to self-regulate by limiting their driving at night, in unfamiliar
areas, on roads with heavy traffic, in bad weather, or alone.
Older drivers do have a higher crash risk in some conditions and locations. According
to the FHWA publication Highway Design Handbook for Older Drivers and Pedestrians (FHWA-RD-01-103), older drivers are more likely than other age groups
to have crashes at intersections, when making left turns, and on limited access
highways when merging, exiting, or changing lanes. Some common areas of
difficulty include yielding, responding to signs and signals, scanning the
roadway environment, staying in their lane, keeping up with the flow of
traffic, passing, and stopping.
Countermeasures
for Common Conditions
What can be done to help
older road users in the face of these changes in ability? According to a 2003 University of Michigan Transportation
Research Institute report, Promising
Approaches for Enhancing Elder Mobility, medical and transportation professionals agree that
the focus of safety efforts should be on helping older drivers and pedestrians
who are able to continue driving and walking safely to do so, rather than
focusing on restricting all older drivers regardless of ability. The challenge
is making roads safer and decreasing mortality while maintaining independence
for older motorists and pedestrians. In other words, what can be done to plan
for their transportation needs?
As
mentioned earlier, aging is a highly individual process, and changes occur at
different rates. After all, there are 80-year-olds who are more productive than
many 18-year-olds. Some 70-year-olds look and act much younger than their
years, whereas others already experiencing serious chronic illness feel and act
even older. Still, a few functional impairments are more common than others.
The focus in transportation planning is on the changes that most people will
experience and the ways that infrastructure can be designed to make mobility
easier and safer for them.
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Older adults such as the driver and passenger in this car differ in the rates at which their driving abilities decline. |
Vision Changes and Improving Roadway Visibility
What actually happens to a person's eyes as they age? Two of the key changes occur in the lens, which focuses light on the retina. The lens becomes less flexible and yellows with age. The reductions in flexibility make it harder to shift
focus from a near object to a far object. In fact, presbyopia, or nearsightedness, is a common age-related visual change. The yellowing of the lens and other changes cause older adults to need more light to see. Although they benefit from
additional lighting, they also are more susceptible to glare and require
significantly more time to recover from it. One of the major consequences of
these and other vision changes is that it is harder for older people to see at
night.
Other changes occur as well, such as declines in
peripheral vision. Because of these changes, older adults often are slower to
react to objects outside of their central focus. Natural declines in peripheral
vision often are made worse by glasses, which usually improve focal vision
rather than vision in the entire visual field.
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This older driver presumably checked her rearview mirror before backing out of her driveway. As people age, their peripheral vision and ability to shift focus from a near to a far object decline. |
A number of infrastructure measures can reduce the
impact of vision declines. One of the most obvious steps is to enlarge roadway
signs and lettering. If drivers can read the information from farther away,
they will have more time to make navigation decisions and can focus on safe
maneuvers. The Manual on
Uniform Traffic Control Devices (MUTCD) recommends sign
and font sizes for various types of signs. According to Hari Kalla, FHWA's MUTCD program manager, "The 2003
edition of the MUTCD includes increased letter sizes for street signs based on
research recommendations for older drivers."
Curves present another visual challenge. Older drivers
may not detect sharp curves, especially at night and wherever the
retroreflective pavement markers have faded. Declines in contrast sensitivity
(the ability to discern brightness differences between adjacent areas) make it
harder for older drivers to notice faded pavement markings, but those markings
provide extremely important information to drivers under dark or rainy driving
conditions.
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This older driver is having his vision tested. |
One technique to improve curve detection for sharp
curves is to use retroreflective pavement markings leading up to the
curve and spaced throughout it. These pavement markings are highly visible at
night, and researchers at FHWA's Turner-Fairbank Highway Research Center
(TFHRC) are looking at configurations that will make it even easier for older
drivers to detect sharp curves. Thomas M. Granda,
Ph.D., team leader for the Human Centered Systems Team in FHWA's Office of
Safety Research and Development, oversees the highway driving simulator at TFHRC. He
says, "Our research team is using both the driving simulator and field research
techniques to determine the best configurations for retroreflective pavement
markings to make curve detection easier for drivers of all ages. And we involve
older adults in all of our pedestrian and driving research."
Musculoskeletal
Function and Improving Intersections
People may move more slowly
with age. Some older adults experience loss of limb strength, flexibility,
sensitivity, and/or range of motion, or reduced ability to rotate the head and
neck. Such changes may be the result of simple joint inflammation and deterioration
(arthritis), muscle atrophy or paralysis related to stroke, or other problems.
Chronic illnesses, such as coronary artery disease, heart failure and emphysema
can greatly restrict and slow physical activity and mobility. General
flexibility and head movements in particular are necessary to physically
operate a motor vehicle, particularly for merging, lane positioning, and
parking.
Reduced
flexibility can affect a variety of driving tasks, especially where drivers
have to visually scan a wide portion of the roadway environment. Some types of
scanning cannot be eliminated, such as looking for other cars, pedestrians, or
traffic signals, but it is important to avoid creating situations where
excessive scanning is necessary. For example, consider skewed intersections
where two roads meet at an angle that is less than 60 degrees instead of at a
right angle. Because of their design, skewed intersections require more head
movement and scanning. New highway projects should avoid skewed designs where
possible. If a skewed intersection cannot be avoided, right turn on red should
be prohibited because some older drivers will have a harder time detecting safe
gaps in traffic.
The
effects of age- and illness-related changes in flexibility on navigating skewed
intersections are apparent. But physical difficulties may not seem relevant to
providing advance guide and street signs. Advance information enables older
drivers to ready themselves to make the appropriate responses, such as braking
or turning. That small amount of extra time can make a difference. Advance
signing enables drivers to focus on making a safe turn instead of having to
look for a street sign at the same time.
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Many older drivers like this motorist may experience reduced range of motion, making it harder to rotate the head and neck and therefore more difficult to navigate skewed intersections |
Cognitive Changes and Making Roadway Navigation Easier
According to NHTSA's Medical Conditions and Driving: A Review of the Literature (1960-2000), the source of the most commonly occurring traffic
violations leading to increased crashes involving older drivers, such as
failure to obey stop signs or unsafe left turns, is not an "obedience" problem but rather "attentional errors." Such errors may signal cognitive decline, which can
develop from a number of conditions, such as the early stages of Alzheimer's disease. Cognitive abilities also may be affected by the
interactions of various medications taken for a number of chronic conditions.
Working
memory is the ability to maintain information active in memory. A classic
example is learning a new phone number and trying to remember it until you can
dial it. With age and illness, the working memory capacity—the amount of
information that can be held in memory at one time—often declines. There are
many different types of attention. Selective attention is used continuously to
filter out extraneous sensory information in order to focus on critical
information, though most people may be largely unaware that they are doing it.
On the other hand, divided attention is used to monitor and respond to multiple
events at the same time. An example is the combined tasks of entering a freeway
while tracking the curvature of the ramp to steer appropriately and keeping a
safe distance from the cars ahead. In general, older adults often find it
harder to screen out unnecessary information, especially when they are in
unfamiliar situations. They may encounter difficulties when performing multiple
tasks at the same time.
Reaction
time is the time from when a stimulus appears to when a physical response is
initiated. The reduced muscular flexibility of older adults contributes to
slower responses. One aspect of age-related slowing in reaction time is slower
information processing in the brain. As a result, older drivers may be slower
to react when a traffic signal turns from red to green or when applying the
brakes during an emergency situation.
Redundant
street name signs can be used to improve the chances of drivers remembering
critical navigation information when they need it. At one time or another, most
people have read a road sign, been distracted shortly afterwards, and then
realized that they could not remember the instructions. The distraction
essentially wiped the information out of working memory. Given that working
memory capacity can decline with age, these types of lapses become more likely
for older drivers. Providing the information several times can help limit this
problem. The repeated messages create opportunities for drivers to notice the
information they need in advance of a decision point so they can prepare to
change lanes or turn if need be.
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This skewed intersection in Atlanta, GA, may pose a problem for older drivers. If a skewed intersection cannot be avoided, right turn on red should be prohibited. |
Older
drivers often prefer driving in familiar and predictable circumstances.
Unfortunately, roadways, even familiar ones, change. For example, work zones
may jolt a driver's expectations because of sudden lane closures or detours.
When a driver encounters new circumstances, an increased burden is placed on
working memory and attention. The driver has to devote more attention and
resources to determining how to navigate the new conditions.
Changeable
message signs are one way that transportation agencies alert drivers to new
circumstances, and designing the messages so that drivers can easily understand
them is important. The last thing any transportation professional wants to do
is present a message that confuses the driver. FHWA's Highway Design Handbook for Older Drivers and Pedestrians provides
preferred strategies for presenting information on changeable message signs.
Signs should be designed for a maximum of two phases (for example, phase 1:
Road Work Ahead; phase 2: Left Lane Closed). For words that are too long to
display, care should be taken in selecting abbreviations. What does ACC mean,
for example? Does it mean "access" or "accident"? What about DLY? Is it "delay"
or "daily"? The more time that drivers of any age have to spend figuring out a
message means the less time they have to focus on safely operating their
vehicles.
Countermeasures
for Changes Affecting Older Pedestrians
Some of the same declines in
musculoskeletal and physical function that affect older drivers necessarily
affect them as pedestrians too. For example, common hip and leg impairments
such as arthritis can limit walking comfort and distance. Loss of limb
strength, flexibility, sensitivity or range of motion, and reduced ability to
rotate the head and neck all can make walking more challenging or impossible.
Because walking is one of the most recommended ways for older adults to
maintain health and prevent injury, the roadway infrastructure should help
increase, rather than discourage, walking.
Just
as roadways can be improved for older drivers, so may the infrastructure be
enhanced for older pedestrians. According to 2004 NHTSA data on pedestrian safety,
adult walkers over age 70 had the highest fatality rate of any pedestrians. Intersection improvements in particular are
important because older
pedestrians are overrepresented in
intersection fatalities.
Many older
adults walk more slowly than the MUTCD recommendation of 1.2 meters (4 feet)
per second used for timing "flashing don't walk" signals. Slower walking speeds
should be used to set traffic signal times in areas where a number of older
adults are likely to be walking. The current MUTCD recommendation is based on
the walking speeds of average, healthy adults, but the MUTCD allows for slower
walking speeds where necessary. A walking speed of 0.9 meters (3 feet) per
second covers nearly all
walkers, including the elderly and people with disabilities.
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Declines in the working memory capacity of older people can affect memory of critical navigation information provided in signs. This change can be addressed in part through redundant street signs. Here, an older man is being tested by an Iowa driver licensing official. |
The
National Committee on Uniform Traffic Control Devices has reviewed research on
this matter and has recently recommended to the FHWA that the MUTCD guidance be
revised to use a more refined process for determining pedestrian signal timing,
using slower walking speeds. Such changes may be proposed in the formal
rulemaking process leading to the next edition of the MUTCD.
Leading
pedestrian intervals, which allow pedestrians at a crosswalk to
start crossing before the light turns green for vehicles driving in the same
direction, are also a good practice. The increased lead times
improve pedestrian visibility in the crosswalk because they will have entered
it before vehicles are allowed to make turns. Giving all pedestrians a headstart may be
advantageous for older drivers as well, making it easier for them to see the
pedestrians.
Countdown
pedestrian signals can be another useful measure. They may reduce older
pedestrians' worry about getting trapped in the road when the traffic light
turns green.
Physical
changes to the roadway environment can be helpful as well. Median refuges do
what their name implies—they provide a safe midpoint for slower pedestrians who
may not be able to complete a crossing in one cycle. In short, the
transportation community has a number of tools at its disposal to help older
pedestrians, and pedestrians in general, cross roads more safely and
comfortably.
Many pedestrian-related infrastructure improvements
will benefit everyone, including walkers of all abilities and wheelchair users.
And many measures that enhance accessibility, per the Americans with Disabilities Act (ADA) and United
States Access Board recommendations, often benefit older pedestrians as
well. In fact, adding curb ramps, reduced cross slope, and clearing the
sidewalk of obstructions are ADA design guidelines that probably improve
conditions for all pedestrians.
"One of the first things municipalities need
to do is to make sure that sidewalks are installed where they do not yet exist,
and that all sidewalks are wide enough, unbroken, level, and not too close to
high-speed roadway traffic," says John
LaPlante, P.E.,
P.T.O.E., vice president and chief transportation planning engineer for T.Y. Lin International. "But there is a bit of a catch-22 that some measures which make it easier for the
elderly to drive may increase traffic overall, making walking even less
feasible for them in many areas," he adds. "One retrofit that might strike a
balance between both needs is squaring corners off, or decreasing turning
radii, which encourages all drivers to slow to make turns, and decreases
crossing distances for pedestrians."
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Arthritis and joint replacements may limit walking comfort for older pedestrians. Reducing the MUTCD design standard for signal timing to 0.9 meters (3 feet) per second can help older pedestrians cross safely. Here, a police officer halts motorists to allow time for an older woman to cross an intersection. |
Looking
to the Future
In the coming decades, older
adults will comprise an increasing proportion of the U.S. population. This is a
positive development for society because it indicates that people are living
longer and healthier lives. But aging, and the chronic illnesses that become
more prevalent with age, may bring about some changes in vision, cognition, and motor skills. These ability changes occur at
different rates for different people, so it is incorrect to assume that
all drivers of a certain age have deficits or are unsafe.
The
transportation network must accommodate larger numbers of older drivers,
pedestrians, and public transit users. Maximizing their ability to use the
network is important since transportation plays such a significant role in
maintaining independence. To the extent that older adults can safely drive or
walk on their own, they will be able to preserve their quality of life.
"Thankfully,
most of the infrastructure changes that communities make for older road users
benefit users of all ages and society as a whole," says FHWA's Alicandri. "There are very few, if any, infrastructure
recommendations that benefit older adults but hinder other road users. If
you're not already an older road user, one day in the future you will be—and
these infrastructure changes will help ensure that you will be able to get
around safely on your own."
Lisa Phillips coordinates the American Medical Association's (AMA) Older Drivers Project. She holds a degree in urban planning from the University of Illinois at Chicago and is a bicycling and walking advocate.
Gabriel Rousseau, Ph.D., is a transportation specialist in the FHWA Office of Safety Programs in Washington, DC. He has a Ph.D. in cognitive psychology from The University of Georgia. He works on human factors and
pedestrian/bicyclist safety issues.
Joanne Schwartzberg, M.D., is the director of Aging and Community Health at AMA, and she also directs AMA's Older Drivers Project.
For more information,
contact Gabriel Rousseau at 202-366-8044 or gabriel.rousseau@fhwa.dot.gov.
Other Articles in this issue:
Road Users Can Grow Old Gracefully—With Some Help
The Evolution of Advanced Research
Following the Flow
Acting Now, Building for the Future
The Battle of Its Life
A High-Tech Route for Freight Efficiency
Gearing Up for an Aging Population