Fall 2014
Many elderly live in poverty, ill health, and inadequate housing Increasingly, many of those over age 65 will be very old—over age 80–85. In the United States, the number of those over age 85 grew 300% between 1960 and 1996—to 3.8 million people, comprising 1% of the U.S. By the middle of the next century, 1 in 20 Americans will be over age 85 Women live longer than men (more female drivers)
See also: ◦ Understanding Older Drivers: An Examination of Medical Conditions, Medication Use, and Travel Behavior by AAA (2014) ( ehaviors%20--%20FINAL%20FTS%20FORMAT%20copy.pdf) ehaviors%20--%20FINAL%20FTS%20FORMAT%20copy.pdf ◦ Millennials in Motion: Changing Travel Habits of Young Americans and the Implications for Public Policy (Oct. 2014) ( SPIRG.pdf ) ( ) SPIRG.pdf
Values can be used for computing the sight distance at intersections
Recommended Design: Skewed Intersection ● In the design of a new facility (or re-design), all intersecting highways should meet at 90 o ● If ROW is restrictive, the skew angle should be no less than 75 o ● If skewed angle smaller, a RTOR prohibition is recommended
Recommended Design: Receiving Lane Width ● 12-ft lane and 4-ft shoulder (critical task: lane positioning) Recommended Design: Channelization ● Raised channelization with sloping curbs preferred over pavement markings ● Use retroreflectorized marking maintained at minimum luminance level ● provide acceleration lane for right-turn channelization Recommended Design: Sight Distance Requirements ● PRT should be above 2.5 seconds for left, right and crossing ● Use a minimum of 8.0 seconds for a left-turn from a stopped maneuver
Recommended Design: Left-Turn Geometry & Signing ● Provide positive offset design with unrestricted sight distance ● Use truck design templates whenever there is a high probability of truck traffic ● When positive offset design is not possible, provide adequate signing and pavement marking
Recommended Design: Curb Radius ● 25 ft to 30 ft to minimize pedestrian crossing and moderate the speed of turning vehicles Recommended Design: Traffic Control for Left-Turn Traffic ● Use separate signal heads ● Use protected-only signals whenever possible (leading rather than lagging) ● Install “LEFT-TURN YIELD ON GREEN” sign ● Green arrow followed by left arrow and then solid red circular red
Recommended Design: Street Signs ● 6-in minimum size ● Use overhead-mounted street signs with mixed-case letters ● Use redundant street-name signs (not mandatory) ● If different street names, the names should be separated and accompanied by directional arrows
Recommended Design: One-Way/Wrong-Way
Recommended Design: Stop Controlled ● Use supplemental sign under stop sign
Recommended Design: Pedestrian Crossings ● Use 2.8 ft/s seconds walking speed Where right-turn lane is channelized Two-stage crossing (median refuge island)
Recommended Design: Pedestrian Crossings
Recommended Design: Exit Signing & Ramp Gore Design ● 1-in letter for every 33 ft distance ● Mixed-case font for overhead signs
Recommended Design: Exit Signing & Ramp Gore Design