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 Roadway Design: Professional Practice

 
Design Controls and Criteria

Driver performance is one of the roadway design criteria that is not quantifiable, but is important. The following excerpt on driver performance was taken from page 42 of the 1990 edition of AASHTO's A Policy on Geometric Design of Highways and Streets.

An appreciation of driver performance is essential to proper highway design and operation. Design suitability rests as much on the ability of the highway to be used safely and efficiently as on any other criterion. When drivers use a highway designed to be compatible with their capabilities and limitations, their performance is aided. When a design is incompatible with the attributes of drivers, the chances for driver errors increase, and accidents and inefficient operation often result.

At the start of the 20th century, approximately 4 percent of American's population was 65 years of age or older. Persons 65 years of age or older accounted for 15 percent of the driving age population in 1986, and will increase to 22 percent by the year 2030.

Elderly drivers and pedestrians are a significant and rapidly growing segment of the traffic stream with a variety of age-related sensory-motor impairments. As a group, they have the potential to adversely affect the highway system's safety and efficiency... Thus, designers and engineers should be aware of the problems and requirements of the elderly, and consider applying applicable measures to aid their performance.