The extensive U.S. freeway system was born in the 1950s when cars were big and drivers young. Many design standards were built around research on college-aged drivers. But the huge block of post-World War II youngsters, the 78 million Americans born between the years 1946 and 1964, is growing older and starting to experience gradual deterioration in mobility, eyesight, hearing and reaction time.
With funds from the 1998 federal surface transportation act, the Transportation Equity Act for the 21st Century (TEA-21), now appropriated and hitting the streets, “We now have the means to wrap a safety net around an aging American highway system and to build the next generation of safer, more forgiving roadways,” said Keith Griggs, ATSSA president.
Improving America’s aging highway system also means making highways more elderly driver friendly. “Continued mobility is one of our elderly constituents’ primary concerns,” said Mike Goodman, an engineering research psychologist with NHTSA. Ensuring continued safe mobility also is one of the U.S. DOT’s major focuses in the coming years.
According to the U.S. Department of Health and Human Services Administration on Aging, the older population—persons 65 years or older—numbered 34.1 million in 1997. But the older population will burgeon between the years 2010 and 2030 when the baby-boom generation reaches age 65. By 2030, there will be about 70 million older persons, more than twice the number in 1997.
People also are living longer. Optimistic projections by the Administration on Aging postulate that, by 2050, males will live an average of 86 years (compared to current projections of 72.5), and females will live an average of 92 years (compared to 79.3 now).
Retirement years are the peak travel time for most people. More drivers overall and a higher proclivity toward recreational travel means there will be many more elderly drivers on the road in the future. In addition, elderly drivers will continue to commute by automobile to their jobs.
The need to focus
Elderly drivers, along with young, beginner drivers, have more accidents per miles driven than any other age group. Paradoxically, taking the elderly out of their cars poses higher risks: The elderly are more likely to die as pedestrians than as drivers. But the impacts reach further than any individual driver, young or old. “Society is at a great disadvantage if senior citizens can’t get around,” said John Eberhard, senior research psychologist with NHTSA. “Decreased mobility often leads to depression, which leads to declining health and, ultimately, institutionalization.”
Since the mid-1980s, engineers, researchers and psychologists at the Federal Highway Administration (FHWA) have been re-examining all aspects of road and highway design, including geometrics, operation, signing and traffic signals, with an eye toward the needs and capabilities of the elderly driver. The culmination of this work was a handbook issued in January 1998, Older Driver Highway Design Handbook (publication no. FHWA-RD-97-135), giving guidelines for improving basic highway safety conditions.
A toolbox of recommendations
The handbook supplements existing standards and guidelines focused on four main problem areas. According to Beth Alicandri, FHWA engineering research psychologist, subtle changes to intersection sight distance, highway exit signage, passing zone length and temporary pavement marking in construction zones greatly improve driving safety.
Research has shown that at-grade intersections, with complex speed-distance judgments under time constraints, are one of the most dangerous driving situations for the elderly. According to the Insurance Institute for Highway Safety, for drivers 80 years and older, more than half of fatal accidents occur at intersections, compared with 24%or less for drivers up to 50 years of age.
Common errors include failure to yield right-of-way and improper turns. The handbook provides recommendations for 16 different intersection design elements, including improved sight distance, left-turn lane geometry and signage and treatment of curbs, medians and other near-ground obstacles.
Weaving and merging
Although freeways overall have the lowest fatality rates compared with other rural and urban highways, older drivers experience great difficulty negotiating freeway interchanges where merging, weaving and lane changing require greater attention and quick reaction times. For example, when merging from an on-ramp to the freeway, many older drivers with reduced head and neck range of motion rely exclusively on their mirrors to find an acceptable gap in the mainline traffic.
Freeway exits, in particular, require the older driver to process a large amount of information at high speeds while navigating their car in close proximity to others. Compounding these difficulties are the elderly drivers’ losses in vision and information-processing ability, sensitivity to glare and poor night vision and reduced physical capability.
“It is important to promote increased legibility of signs and markings,” said Griggs. To this end, ATSSA members are continually devising new materials for roadway safety, for better sign and road marking reflectivity and for components of the work-zone safety systems.”
The handbook recommendations are focused on improving exit sign visibility (letter size, directional arrows and lighting), acceleration/deceleration lane geometry improvements, interchange lighting and better “wrong way” signage.
For many years, roadway designers have recognized horizontal curves as a major safety problem, especially when drivers take the curves too fast. With reduced visual acuity, physical capability, cognitive performance and perceptual abilities, horizontal curves become even less forgiving and more dangerous for the elderly driver.
Improved pavement delineation and markings on horizontal curves, wider shoulders and better warning signs for limited sight distance locations are some of FHWA’s recommendations to improve roadway conditions for the elderly driver.
Research has shown that the elderly driver responds to unexpected stimuli much more slowly than the younger driver does. Construction work zones are prime locations for the unexpected, but older drivers tend to respond to these new road conditions in an “automatized” way.
ATSSA makes an investment in training for setting up the most effective and safe work zones. More and more roadway work is being performed at night. “Because nighttime vision is such a significant issue for the elderly, improved nighttime traffic control and signage is essential,” said Griggs. “We are completely upgrading ATSSA’s Nighttime Traffic Control video and training program to improve work-zone safety.”
The handbook provides several recommendations to help protect the driver, surrounding vehicles and highway construction workers. A flashing arrow panel is the preferred advance signage for lane closure. The means by which information about road construction is transmitted to the driver is shortened and simplified. Channelization devices are placed so that drivers have longer to respond.
Facing vision head-on
Eye reaction time slows with age, making it more difficult to filter out distractions and make quick decisions when driving. Because night vision is even more seriously constricted, driving along brightly lit urban commercial strips becomes as difficult as maneuvering rural back roads. NHTSA research has shown that 311of all crashes and 525of fatal crashes occur at night (including dawn and dusk) or during other degraded visibility conditions.
Intelligent transportation systems (ITS) integrate automotive electronics, automobile/roadway communications and computerized control systems. One form of ITS close to development and implementation is adaptive cruise control, which will automatically maintain a safe distance from vehicles ahead. With a lane tracking system, imminent departure from the roadway will be predicted by on-board electronics and the driver will be alerted in time to recover. Another form of ITS called cooperative intersection systems warn of the presence of oncoming, conflicting traffic to reduce the risk of intersection collisions.
Vision at night and during inclement weather conditions will be enhanced by systems that sense images that the driver does not normally perceive and convert them into visible forms for detection by the driver. One system relies on infrared imaging, in which a camera views the forward scene, processes it and projects the images onto the windshield, thereby allowing the driver to see what they cannot with the naked eye.
A spectrum of improvements
From simple adjustments to roadway geometry and signage to complex technological advances in the driver/roadway interaction, improvements are gradually being instituted to make our nation’s roads safer for the elderly driver. FHWA’s Alicandri said, “We found that improving the roads based on the needs of the elderly automatically improves the roads for all drivers.”
Some individuals have concerns that these technological systems may actually overload drivers with information and distract them from the act of driving. The ability of older drivers to see and discern these displays, and then react to them, is an important evaluation factor to engineers developing these systems. But most important is the research and design community’s heightened awareness of the greater needs that the elderly driver will place on the roadway system in years to come. -