The purpose of this research is to investigate collectively both the highway capacity and analysis implications resulting from an older driving population in the US. Highway capacity considerations and the importance of a micro-level understanding of increasing numbers of older drivers are discussed first. A demographic analysis concludes that at least a 6.7 per cent increase in drivers 65 or older by the second or third decade of the 21st Century is likely. A brief synopsis of why an increase in older drivers will cause certain highway capacity impacts and how increased delays occur is presented next. The major portion of this paper reviews highway capacity analysis considerations from both theoretical both theoretical and applied example perspectives. Highway capacity analyses and resulting implications are studied for general roadway segments, two-lane and multi-lane rural roads, weaving areas, ramps, for both unsignalised and signalised intersections, and when incidents/accidents occur. The major contributions of this research are increased awareness of highway capacity analysis issues, data needs, examples of highway capacity implications, and consideration of system modifications that may be required to accommodate increasingly numbers of older drivers. (A)
Abstract