Semisequicentennial Transportation Conference Proceedings
May 1996, Iowa State University, Ames, Iowa

Interacting Vehicles and Roadways with Elderly Drivers on Missouri Highways

Glenn A. Carriker, John J. Prince, Robert L. Baldwin, Leanna Depue, Gina Geloso, and Christine Hessman

The Missouri Safety Center and the Department of Safety Science and Technology,
Central Missouri State University,
Warrensburg, Missouri 64093.

Since the late 1980s, the southwestern portion of Missouri has experienced substantial growth in the population of persons age 60 and above. This study examined these persons as elderly drivers to determine 1) their perception of highway construction and repair needs of the area; 2) demographic/profile information; 3) driving experience including accident involvement; 4) long-range highway planning by the Missouri Highway and Transportation Department related to the roadway improvements that the respondents perceived as needed; and 5) purchasing habits related to the feasibility of intelligent highway systems. All respondents had renewed their driver's license within the past two years and lived in the selected counties. The response rate was 64 percent. Analysis of the responses from the surveys refuted many of the stereotypes of the elderly as drivers. Annual mileage driven indicates that exposure estimates for the nation are much too high for this study population. The type of equipment purchased on new cars by the respondents does not indicate a propensity for expensive options like those needed for highway interactive automobiles. Perceptions of needed changes for improving the roadways coincided with the long-range plans of the Missouri Highway and Transportation Department.

Since the late 1980s, the southwestern portion of Missouri has experienced substantial growth in population of persons age 60 and above. This growth is not only in establishing permanent residency but also in areas of seasonal residency, such as Springfield and Branson. Roadways serving this area were not designed for the growth capacity experienced in the region.

The study was four-fold: first, to survey older resident drivers to obtain their input on the needs of the area; second, to capture data on accidents involving the older driver; third, to look at the long-range plans developed by the Missouri Highway and Transportation Department for the area to determine if the needs perceived by the older driver were being addressed; and, fourth, to collect data on the purchasing habits of drivers in the survey area to determine the feasibility of incorporation of the intelligent highway system (smart cars) into the roadway improvements.

The counties that were included in the study were Green, Taney, Howell, Camden, Laclede, Barry, Lawrence, Polk, Christian, Stone, Pulaski, Texas, Webster, Dallas, Cedar, Douglas, Hickory, Ozark, and Dade.


The study was designed with a four-tier approach for data collection. Drivers who fell into the 60-plus age group were identified. Second, a survey of new car dealers in the study area was made to determine buying habits of this age group. Third, data were analyzed from the state's computer system to limit the study to accidents within the study area and drivers in the appropriate age group. Fourth, a review of the Missouri Highway and Transportation Department's recent and future Roadway Construction and Maintenance Plan for the area was made.


The construction of the first phase of our study involved two parts: 1) determining the survey population and 2) developing and testing an instrument. The research team elected to limit the study to drivers who were at least 60 years of age or older, who had renewed their driver's license within the past two years, and who resided in a 20-county region in the southwest to south central portion of the state. This study area included both the Springfield and Branson areas. Utilizing the 1990 Census data, a computer program selected 2,000 drivers (age 60 or older) from the 20 counties, proportional to the population of each county. One additional variable used during this screening process was to match the ratio of males and females to the county population ratio. Finally, the computer program processed this database with a final screening designed to randomly select 2,000 names from the database. These names were printed out in label format for the research team.

Simultaneously, the task of instrument design was being addressed by the instrument design team. This team was selected to consist of persons with gerontology experience and survey expertise, safety experts, and driver trainer/evaluation experts. Their task was to develop a series of questions to capture the appropriate data for the study.

The primary data capture areas for the driver survey were as follow:

(A) Demographic and profile information

(B) Specifics about the car the respondents drive

(C) The roads driven

(D) Comments from drivers surveyed

In all, 2,000 surveys were disseminated. Of these, 20 were returned because the persons had moved or were deceased. This reduced the survey to 1,980. Of the remaining, 1,284 were returned completed.

Sixty dealers were mailed a survey instrument. Of the dealers who were sent a survey, 32 responded. This provided a 53 percent return rate.

Accident data collected were categorized as Fatal, Personal Injury, or Property Damage. The data included age, sex, location by type of roadway, weather, time of day, day of week, and month. Also collected were contribution factors to accidents involving the study group's area.

The research team decided there was a need to conduct a comparison between those locations and improvements the Missouri Highway and Transportation Department had in its planning or construction process, and needed improvements suggested by respondents.

Data Analysis

The respondents were almost equally divided along gender lines with 51 percent female and 49 percent male. Over 67 percent have lived at their current address for over 10 years. Fifty percent of those reporting lived in a rural area, and nine percent indicated they were retired. Sixteen percent were still employed. The vast majority of respondents, 91 percent, have been driving for 35 years and longer. Fifty-eight percent are required to wear glasses when they drive.

Those who were mailed survey forms were asked to provide their opinion of needed roadway improvements in their area. Among the notable responses, 81 percent indicated that center line reflectors would be helpful to their driving. Seventy-four percent indicated that shoulders for stopping were needed. A little over 80 percent reported that the elimination of single lanes and narrow bridges were a needed roadway improvement in their area. Seventy-three percent reported that the correction of dangerous intersections in their area was a needed improvement.

As far as driving experiences were concerned, 45 percent responded that they mostly drove on two-lane rural roads.

The driving exposure of the respondents was divided as to miles-per-week driven. Thirty-six percent reported driving between 51 and 100 miles per week. Thirty percent drove between ten and fifty miles per week, while 29 percent reported driving 100 or more miles per week.

Of the respondents, 92 percent were able to keep their vehicle speed within the posted limits. A self-reported 89 percent wear their seat belt as a driver, while 87 percent wear their seat belt as a passenger. Eighty-five percent of those responding indicated they were comfortable driving at 55 miles per hour, and 78 percent were also comfortable driving at 65 miles per hour. Further, 67 percent had no difficulty driving in city traffic, and 62 percent indicated that they had no difficulty reading signs after dark.

The type of vehicle driven most often was also asked of the respondents. Thirty-four percent drove a full-sized car most often. Twenty-seven percent drove a medium-sized car, and 13 percent drove a full-sized pickup. A little over 84 percent of the respondents had no type of communication equipment in their vehicle. Senior drivers were involved in 13.1 percent of all accidents in the study area. They were involved in 11 percent of the personal injury accidents, 19 percent of the fatal accidents, and 13 percent of all other accidents.


The data from the research study provided several excellent pieces of information. The surveys (driver and dealer) had a significant return rate, which indicates a high degree of interest in the issue of Missouri roadways. The responses provided insight regarding hazardous roadways, and identified specific locations regarding highways, intersections, and bridges, etc., that the respondents felt needed improvement. When these suggested improvements were cross-checked with existing plans for highway improvements as indicated in the Missouri Highway and Transportation Department's 1993 Work Plan, over 70 percent were already either under construction or were listed in the long-range plan.

Another important piece of information was the average annual mileage driven by persons 60 years of age and older, which was reported as approximately 5,000 miles. Other sources have indicated an annual mileage of 12,000 to 15,000 per year for this age group. The study data have produced a unique view of the older driving population in this area of the state. The data have revealed a new view of the annual mileage driven; the type of equipment purchased on new cars; types of equipment likely to replace present vehicles; kinds of driving problems with equipment, roads, and other drivers; as well as perception of changes needed to improve highway safety. Highway improvement planning was clearly on target, and enforcement efforts are needed in specific areas.

This study was funded by the University Transportation Center's Program of the U.S. Department of Transportation, with additional assistance and funding from the Missouri Highway and Transportation Department and Central Missouri State University. The results and views expressed are independent products of university research and are not necessarily concurred in by the funding agencies.

CTRE is an Iowa State University center, administered by the Institute for Transportation.

Address: 2711 S. Loop Drive, Suite 4700, Ames, IA 50010-8664

Phone: 515-294-8103
FAX: 515-294-0467


Iowa State University--Becoming the Best