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Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations
This magazine is an archived publication and may contain dated technical, contact, and link information.
|Publication Number: FHWA-HRT-10-002 Date: Jan/Feb 2010|
Publication Number: FHWA-HRT-10-002
Issue No: Vol. 73 No. 4
Date: Jan/Feb 2010
These older pedestrians may need extra time to cross this signalized intersection.
This overview summarizes a series of articles that appeared in Public Roads recently, focusing on transportation challenges that face an aging population.
According to the 2000 census, Americans aged 65 and older make up 12.4 percent of the U.S. population. By the year 2030, one in five Americans will be over 65. To address the increasing mobility challenges confronted by seniors--both motorists and pedestrians--the transportation community is looking at safety improvements in the design of highways and vehicles.
Seniors 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 among 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, or in inclement weather.
According to Dennis Utter, director of the Office of Traffic Records and Analysis, National Center for Statistics and Analysis, "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."
For older people, however, crashes more frequently lead to death. Older motorists and pedestrians may be frail due to chronic medical conditions and may take much longer to recover from severe injuries.
In a series of nine articles that started in 2006, Public Roads magazine examined a number of issues affecting the mobility of senior motorists and pedestrians. The first article described activities and programs that address the challenges created by the growing number of senior road users. Subsequent articles discussed modified infrastructure design, new guidelines for reducing crashes involving seniors, improved signage to help senior motorists, enhanced safety at intersections for older drivers and pedestrians, European road designs targeted to helping senior road users, supplemental transportation for seniors, new vehicle technologies that can aid older motorists, and intelligent transportation systems that are helping coordinate transportation for individuals in human services programs.
Activities and Programs
The first article, "The Older Driver Comes of Age," discusses Federal and State activities and programs that address the mobility challenges faced by seniors.
At the Federal level, the U.S. Department of Transportation (USDOT) identified priorities such as roadway designs that take into account the needs and limitations of older road users, vehicle designs that protect fragile older occupants, and effective assessments of senior-driver competencies. In addition, two decades of research by the Federal Highway Administration (FHWA) culminated in publication of the Highway Design Handbook for Older Drivers and Pedestrians (FHWA-RD-01-103), which focuses on safety for senior road users at intersections, interchanges, curves and passing zones, construction work zones, and highway-rail crossings.
At the State level, one of the primary interests is driver licensing and testing. In addition, a number of States are looking at specific mitigation measures such as improved signs, signals, and pavement markings to increase senior safety. One State even developed a showcase roadway with modified signs and signals.
Professional organizations and academic institutions also are exploring ways to help older road users. Activities include specialized training and conferences focused on mobility for seniors.
The Aging Mind and Body
The second article, "Road Users Can Grow Old Gracefully--With Some Help," describes age-related physical and cognitive changes, including reductions in peripheral vision, loss of visual acuity, and yellowing of the cornea; physical changes, such as restricted neck movement; and cognitive changes, including degradation in selective and divided attention, plus slower response time.
Construction work zones, especially at night like this one, can create extra challenges for older drivers.
Older drivers are more likely than other age groups to have crashes at intersections, particularly 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 the lane, passing, stopping, and keeping up with the flow of traffic.
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 continue driving and walking, if they are able to do so safely, rather than restricting all older drivers regardless of ability. Changes in vision, cognition, and motor skills 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.
To deal with vision changes, one obvious step is to enlarge roadway signs and use certain fonts for lettering. Another is to determine the best configurations for retroreflective pavement markings to make curve detection easier. Advance signing enables drivers to focus on making a safe turn instead of having to look for a street sign at the same time.
To address changes in driver flexibility, it is important to avoid skewed intersections where two roads meet at an angle that is less than 60 degrees instead of at a right angle.
This skewed intersection in Atlanta, GA, may pose a problem for older drivers. If a skewed intersection cannot be avoided, a right turn on red should be prohibited.
Older adults often find it harder to screen out unnecessary information, especially when they are in unfamiliar situations. Changeable message signs are one way that transportation agencies alert drivers to new circumstances.
Just as roadways can be improved for older drivers, so may the infrastructure be enhanced for older pedestrians. Median refuges provide a safe midpoint for slower moving pedestrians who may be unable to complete a crossing in one cycle.
"Thankfully, most of the infrastructure changes that communities make for older road users benefit users of all ages and society as a whole," says Elizabeth Alicandri, director of FHWA's Office of Safety Programs. "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."
Reducing Crashes, Fatalities, and Injuries
The next article, "Gearing Up for an Aging Population," deals with planning strategies for improving the roadway and driving environment to better accommodate older drivers, identifying high-risk older drivers and intervening to lower their crash risk, improving the driving competency of older adults in general, and reducing the risk of injury and death to older occupants involved in crashes.
To help State departments of transportation (DOTs) meet the targeted reduction in the national highway fatality rate, the Transportation Research Board's (TRB) National Cooperative Highway Research Program (NCHRP) published a series of guides for improving highway safety. One volume of this series is NCHRP Report 500: Volume 9: A Guide for Reducing Collisions Involving Older Drivers (Report 500).
Report 500 includes 5 overarching objectives and 19 specific strategies. The objectives are to (1) plan for an aging population, (2) improve the roadway and driving environment, (3) identify high-risk older drivers, (4) improve the driving competency of older adults, and (5) reduce the risk of injury and death to crash-involved older drivers and passengers.
Under these objectives, many of the strategies address specific roadway design and traffic operation changes that can improve safety for older drivers. "The most important thing," says Tom Welch, Iowa's State transportation safety engineer and a contributor to the guide, "is that engineers realize that the 'design driver' for the 21st century is no longer a 45-year-old male. It's someone in the 65-plus age group, and it may just be their mom."
The strategies include encouraging States to review and update procedures for assessing medical fitness to drive, including training license examiners (department of motor vehicles personnel responsible for issuing drivers' licenses) and working with State medical associations to educate the health community about the important role that physicians can play in assessing and counseling older patients who drive.
Although some people can be helped to continue driving by appropriate restrictions on their licenses, others may require special adaptive equipment installed in their vehicles or evaluation and training by an occupational therapist or other specialist. Educational opportunities for older drivers can range from simple brochures and other print materials to self-assessment tools; refresher classes; or one-on-one, behind-the-wheel evaluation and training.
A sampling of the other strategies: educate older drivers on how to assess their own driving skills; ensure that DOT traffic engineers take into account the differences in the capabilities of older drivers and avoid standard assumptions about driver capabilities; and link the issue of older people's mobility with land use planning to reduce isolation caused by lack of access to transportation.
Signs, Signals, and Stripes
In the fourth article, "Marking the Way to Greater Safety," the authors describe how bigger and brighter signs, more conspicuous signals, and wider stripes can make highways safer for older road users.
Visual changes affect the distance at which older drivers can see and recognize the writing on signs and may make it more difficult for them to detect signals and pavement markings. From an engineering standpoint, opportunities to enhance drivers' abilities to detect signs and comprehend sign messages include: sign legibility, placement, brightness (retroreflectivity), and size.
In terms of legibility or readability, research conducted in the 1990s resulted in a new font, Clearview, that provides faster word recognition at greater distances. In the last decade, several indepth studies have shown that the Clearview alphabet's legibility represents a 16 percent improvement in recognition distance by older drivers.
The use of uppercase/lowercase letters also adds to enhanced legibility. In some instances, signs can be placed in the driver's direct line of sight.
Brighter sheeting materials make signs more conspicuous, especially at locations with high levels of visual "noise," such as guide and regulatory signs in the background. Research also shows that the detection distance for fluorescent signs is significantly greater than nonfluorescent signs for both younger and older observers, though the older drivers reaped the greatest benefit.
Twenty-nine out of 50 State DOTs report that they use longitudinal pavement markings wider than the specified 4-inch (10-centimeter) minimum in at least some situations and cite visibility improvement as the primary reason. Also, some State DOTs are using high-contrast, black-on-white and black-on-yellow markings to increase the conspicuousness of their lane lines and centerlines on light-colored concrete pavements.
This Detroit-area overpass offers a side-by-side comparison of the oldstyle Series E font (left sign), previously specified by the Manual on Uniform Control Devices (MUTCD), and the new Clearview font (right sign). Notice the larger green area within the enclosed loops of the lowercase letters, in the Clearview font.
Although national standards do not mandate that pavement markings must perform well in wet conditions, many State DOTs are using a variety of strategies to ensure just that. The majority of State DOTs are using oversized glass beads in their paint markings to improve wet-night recognition of edge and centerline markings.
Probably one of the most overlooked and easiest remedies for making signals more conspicuous is the location of the traffic signal heads. Visual capabilities tend to diminish with age, which includes a reduction in the visual attention window, also known as the useful field of view--the area within which the driver can detect and respond appropriately to information. Placing or relocating signal heads within that visual attention window can be accomplished by placing them overhead near the center of the travel lane, preferably one per through lane.
Signal backplates (thin strips of material on all sides of a signal housing) are commonly used by many States to provide a background for improved visibility of the signal indications, especially at locations where the lights are viewed against a bright sky or confusing background. FHWA's older drivers handbook cites studies showing that backplates can increase the intensity of the signal face by 33 percent.
This added left-turn lane was part of a city-wide, low-cost safety initiative in Winston-Salem, NC.
"Older Drivers at a Crossroads," the next article, discusses design and operational treatments that simplify traffic movement in intersections and therefore driving decisions. According to FHWA's older drivers handbook, "The single greatest concern in accommodating older road users, both drivers and pedestrians, is the ability of these persons to negotiate intersections safely."
Maneuvering a vehicle through an intersection requires the visual acuity, physical dexterity, and rapid mental processing capacity to make simultaneous decisions regarding lane choice, vehicle speed and alignment, braking, acceleration, and continuous vehicle positioning relative to other vehicles in the intersection. Among the cognitive challenges is the need to constantly process and prioritize multiple streams of changing information at once, such as pedestrian movements, signs, pavement markings, and lane alignments.
Transportation agencies can employ a wide range of intersection design and operational techniques. For example, traffic signal visibility can be improved by increasing the size of the lens, adding new signals, and repositioning existing ones. Another strategy is converting roadway corridors, under certain traffic loads, from four-lane to three-lane cross-sections.
Several techniques are available to prepare motorists for intersections. Advance street name signs ease the burden on left- or right-turning drivers by confirming location well before the turn. Advance lane use signs, indicating mandatory or allowable use of specific lanes, give early guidance to drivers so that they do not find their vehicle in the wrong lane at an intersection. Finally, advance pavement-marking messages can be especially beneficial to road-weary drivers whose peripheral vision and sign-reading skills may be restricted, but who may still respond to messages painted on the pavement.
The FHWA older drivers handbook lists several reasons why executing a left turn in the presence of oncoming vehicles becomes more difficult for drivers as they age. Foremost among them is the age-related decline in the ability to detect a perceived change in the size of a moving object--and thus judge safe gaps in traffic.
Countermeasures include eliminating the direct left turn at inter-sections and routing left-turning motorists through a median U-turn, a right-bearing loop, or some other method. Even though these strategies require vehicles to travel extra distance, research shows substantial safety benefits.
Other strategies include roundabouts and dotted-line marking to delineate the turning path. Exclusive left-turn lanes provide drivers with a safe haven in which to wait for an acceptable gap.
This crossing in Hampshire, Britain, is especially helpful to older people. The prominently painted â€œSLOWâ€� on the roadway get driversâ€™ attention, as does the â€œElderly peopleâ€� sign.
Providing a separate lane for right-turn traffic segregates the straight and turning traffic movement and has the potential to reduce rear-end crashes. Left-turning drivers use their turn lane to wait for a gap; the right-turn drivers use their separate lane to lower their speed to make a comfortable turn.
The European Take on Senior Mobility
In "Old World Ways," the sixth article, the author describes European road designs for helping older drivers and pedestrians. The European approach emphasizes serving pedestrians.
Older pedestrians seem to have special difficulty in certain situations: at busy two-way streets; at intersections with heavy traffic, particularly where there is no center refuge; in complex situations, where vehicles can come from several directions; at light-controlled crossings where traffic is allowed to turn across pedestrian routes; and in situations where right turn on red is permitted, so turning traffic can threaten pedestrians unexpectedly.
In Europe, the first and most straightforward strategy for protecting older pedestrians from vehicles is to separate the two modes of travel. Pedestrian streets involve directing traffic away from areas of high pedestrian activity.
Another strategy is land use planning involving designing communities so that pedestrians can travel between their homes, shops, work, leisure activities, and health-care sites by short walks and without crossing major roads.
One of the most effective ways to improve surroundings for pedestrians of all ages is to reduce traffic speeds. Techniques for reducing traffic speeds range from setting appropriate speed limits to automatic camera enforcement, traffic calming, and various engineering strategies such as street narrowing.
Automatic enforcement of speed limits by camera is widely applied. And when employing traffic calming techniques, European countries commonly will narrow one-way urban roads to about 9.8 to 13.1 feet (3 to 4 meters), using bollards (posts) to define the boundary between roadway and pedestrian space.
Short of using bollards, curbs, or other physical obstructions, roads can be made to look narrower by painting boundaries on them using white lines, and by hatching areas to indicate where motorists should not drive.
Other strategies are sidewalk extensions to narrow the roadway at pedestrian crossings and at intersections in residential areas; central refuges for pedestrians; pedestrian phases for traffic signals at intersections; midblock light-controlled crossings, where a walker can call for a pedestrian green phase that stops traffic; speed control tables at pedestrian crossings; and speed tables to continue sidewalks across side roads where they join more major roads.
Technology also can play a role. Light-controlled crossings reduce the need for judgment of speed and distance, people detectors at signals can match walk times to the actual pedestrians, and cameras can enforce speed limits and detect vehicles running red lights.
Professional associations and service providers adapt public transit, shuttle services, and other modes of transportation to the needs of the elderly, as shown here by the ramp that enables these seniors to board the bus using their walkers.
The seventh article, "Better Options for Older Adults," explores Supple-mental Transportation Programs (STPs) nationwide. According to a 2004 study, 20 percent of adults age 65 and older do not drive. Reduced mobility translates into 15 percent fewer trips to the doctor for nondriving older people and 65 percent fewer trips for social, family, and religious purposes.
To address this need, many communities and organizations nationwide have created STPs for seniors to add to traditional transportation services. Although some STPs may provide transportation to people with disabilities and even to the general population, most were created to serve seniors, especially those who are frail and in need of assistance. Similar to traditional services, they offer transportation to a variety of destinations. Most STPs also supply "supportive transportation" in the form of door-to-door and door-through-door assistance. They may even arrange for an escort to stay with a passenger at a destination. In many instances the STP driver or escort is a volunteer.
In years past, family members or friends were expected to help older adults who no longer drive. But today in the United States, multigenerational homes are no longer common, and many older drivers live a great distance from family members. Therefore, fewer stay-at-home caregivers are available to fill the driving gap. Many nondriving seniors depend instead on public and community-based transportation services, such as fixed route, circulator route, paratransit, dial-a-ride, taxi service, and human service transit programs. However, many communities do not offer these services, and even where they are available, older adults may be unable to use them because of the physical conditions that forced them to give up driving in the first place.
Many in the aging-service community note the difficulty if not impossibility of stopping driving if no alternative is available. Simply having options, however, may not be sufficient, as transportation services must be "senior-friendly." The "Five A's of Senior-Friendly Transportation" include availability, accessibility, acceptability, affordability, and adaptability.
Although some STPs are large and costly to operate, the majority are relatively small and inexpensive. Annual budgets by 2007 ranged from $1,000 to $9.8 million, with a median of $58,000. Thirty-three percent of STPs target rural areas, 44 percent use automobiles as their transportation vehicles, and 49 percent can provide escort services. Although 46 percent of the STPs charge fees, 75 percent draw on grant revenue, and 23 percent tap into funding from Federal, State, or local government for some or all of their support. (The figures do not add to 100 percent because STPs typically draw on a mix of funding sources.) Although driver recruitment and funding are said to be major challenges, the fact that the STPs average 24 years in service suggests they are remarkably successful in sustaining their operations.
As eyes age, the effects of nighttime headlight glare become more pronounced, as this photo of a city street on a rainy night suggests. Now being researched are advanced headlight systems that can adjust their lighting pattern to changing conditions and hence reduce glare.
The eighth article, "New Vehicle Technologies May Help Older Drivers," describes night vision enhancement, adaptive cruise control, lane departure warnings, and other innovative vehicle systems.
According to FHWA's Highway Statistics 2005, the United States had more than 29 million older drivers in 2005, accounting for 15 percent of the U.S. driving population. In addition, 21 percent of U.S. purchasers of new passenger cars in 2006 were 65 years old and over. Today, a number of advanced technologies have made their way into the vehicles that are on the road now.
For advanced technologies to provide a benefit without creating new safety problems, their design and operation have to be compatible with the needs and capabilities of older drivers. In addition, some of these technologies might encourage older adults to continue driving well beyond when they would ordinarily cease operating vehicles, introducing other age-associated driving challenges.
Until night vision systems are improved, older drivers--like all motorists--will have to rely primarily on headlamp illumination to guide them at night. Almost any attempt to increase the light to improve seeing distance will increase glare for other drivers. The National Highway Traffic Safety Administration is investigating the potential of adaptive front lighting systems to help resolve the tradeoff between visibility and glare.
Adaptive cruise control (ACC) is a system that can maintain a set distance to the vehicle ahead ("lead vehicle") automatically within a given speed range. ACC was available in 26 vehicle models in 2005 and 2006.
Current lane departure warning (LDW) systems use a camera to analyze roadway markings and provide a warning to alert a driver who has moved out of the lane. LDW systems were introduced first in 2005 by one automaker.
To help prevent lane change crashes, technologies have been developed to detect and warn drivers of vehicles in their blind spots. If the warning systems enable older drivers to spend less time looking to the side when changing lanes, the drivers can focus more on the forward scene.
"Parking aids" marketed as convenience features include sensor-based systems that indicate to the driver the distance between the rear bumper and an object by means of an audio or visual display.
Invehicle navigation systems can extend older drivers' mobility by giving them more confidence when traveling in unfamiliar locations. For older drivers who have difficulty searching for street signs, the voice directions can help lower their visual workload.
This woman with the Cape Cod Regional Transit Authority in Massachusetts is pointing to a mobile data computer, an ITS application that enhances real-time communication between drivers and dispatchers.
A system that alerts drivers when they are in danger of violating a stop sign or red light could reduce the occurrence of these crashes. If these systems match the performance capabilities of older drivers, they will have the potential to reduce a significant safety problem.
ITS Transportation for Human Services Programs
The final article, "Mobility Services for All," describes the use of intelligent transportation systems (ITS) to help coordinate human service transportation systems. Most ITS applications relevant to human service transportation are proven and well-documented technologies with widespread deployment. However, field deployment is limited to fixed-route applications by a single agency. Even when used for human service transportation, existing ITS applications are largely related to fleet management and operations for efficiency gains, and less to customer-oriented functions such as automated reservations and trip planning through simplified points of access.
A lack of relevant empirical evidence on lessons learned, returns on investment at the individual system levels, limited financial resources, and lack of technical expertise are the most common challenges facing local stakeholders in promoting ITS for human service transportation.
Eight sites around the country selected by USDOT for demonstration projects are exploring the technical and institutional feasibility of creating an ITS-enhanced human service transportation system. The selections represent a variety of operational environments from large urban to rural areas, various lead agency types from transit agencies to local and regional government entities, and different levels of ITS deployment.
Key products of the demonstration are replicable and scalable models of ITS-enhanced human service transportation systems. The model systems will address three areas: (1) creating simple points of access for all, (2) embracing a comprehensive set of transportation services, and (3) utilizing ITS technologies to enhance efficiency and accessibility.
A successful model will differ from place to place and from system to system, depending on factors such as the type of area (urban or rural) and local, political, and institutional settings. Communities should attempt to broaden the level of stakeholder participation and establish a common vision for what the local human service transportation system should be like.
After conducting operational tests, workshops, and research, FHWA and other organizations found a number of benefits from ITS applications in advancing human service transportation. These technologies can boost service productivity, facilitate service coordination, and enhance system accessibility.
Transportation for Aging in Place
It is widely known that Americans today are living longer than past generations. What is not always known is how to make sure those additional years of life are productive and enjoyable. A major factor continually cited by seniors themselves is their need for continued safety and mobility as they age. The vast majority of seniors prefer to age in place, to grow old in the communities where they raised their families, where they have roots. Transportation that enables seniors to remain in their homes, to remain engaged in community life as active and contributing members, has been cited as the critical link that makes all else in life possible.
Michael F. Trentacoste is FHWA's associate administrator for Research, Development, and Technology and director of the Turner-Fairbank Highway Research Center. Previously, he was director of FHWA's Office of Safety, Research, and Development and director of FHWA's Office of Highway Safety. Prior to that position, he was with the Office of Motor Carriers and directed research, rulemaking, field operations, and policy and planning functions. He has a bachelor's degree in civil engineering from Manhattan College and an M.S. in transportation from the Transportation Center at Northwestern University.
To learn more about any of these topics, see the complete articles at www.fhwa.dot.gov/research/topics /safety/humanfactors/olderdriver/pubroadslist.cfm. For additional information, contact Michael F. Trentacoste at 202-493-3999 or firstname.lastname@example.org.
Senior Mobility Series
A Guide for Reducing Collisions Involving Older Drivers
In 2004, when Report 500 was published, the Michigan DOT and partner organizations decided to address the report's strategies for possible implementation. The following bullets highlight current Michigan strategies that comply with Report 500's recommendations:
Kimberley Lariviere, Michigan DOT
Resources on Senior Mobility