In the future, a larger percentage of drivers will be older people, with age-related diminishing performance capabilities resulting from changes in sensory, perceptual, cognitive, and psychomotor functions. General improvements in the design, use, and application of traffic control devices are believed to be necessary to accommodate the changing driving population. Although recent studies have identified such improvements to accommodate diminished driving performance, there has been only limited field testing of them. The FHWA study entitled Traffic Control Design Elements for Accommodating Drivers with Diminished Capacity found through lab studies that improved sign displays and redundancy may be beneficial to the older driver. In the case of urban intersections, it was shown that redundant upstream signing for left-turn signals and special sign displays facilitate rapid and appropriate decision-making.

The primary objective of this research is to determine through field tests which traffic control device improvements enhance driver performance with particular emphasis on older drivers. The tasks associated with this research will include: (1) Conduct a literature search and review relevant, on-going research to identify potential improvements in traffic control devices (i.e., highway signs, pavement markings, and traffic signals) and their applicability to the specific needs of older drivers. This task should produce a summary of the major efforts and practices being used by state agencies. (2) Define analytically the characteristics of the older driver that should be considered in the design, use, and application of traffic control devices. (3) Identify those driving and roadway situations that create problems for older drivers where traffic control devices offer potential for enhancing the safety and mobility of older drivers. (4) Develop a research plan to evaluate the effectiveness of the highest ranked improvements. The research plan shall include experiments that assess driver performance and/or device effectiveness in dynamic, multi-task driving situations. (5) Prepare an interim report which summarizes the efforts and findings of the initial tasks, provides recommendations for the improvements to be studied, and describes a research plan for field tests. (6) Execute the research plan with procedures to ensure the integrity of data gathered. Evaluate the data gathered in the field studies and document the findings. (7) Recommend improved procedures for design and placement of traffic control devices to aid the older driver. Assess the costs and benefits associated with improvements to individual device installations and with implementation systemwide. The contractor will present the findings of the study to a professional group as designated by the panel to obtain additional feedback. (8) Prepare a final report, which documents the efforts and findings of this research.

Status: The revised final report has been received and a decision has been made not to publish the contractor's final report since much of the material has been already incorporated in the FHWA's Older Driver Handbook.

Product Availability: The contractor's final report which documents the field tests that were conducted is available on request from the NCHRP.