160 likes | 332 Views
Engineering Safer Intersections. James Bonneson Texas Transportation Institute November 14, 2001. Objective. Define engineer’s role in designing, operating, and maintaining safe intersections. Scope. Emphasis on the safety afforded motorists, pedestrians, and bicyclists at intersections. .
E N D
Engineering Safer Intersections James Bonneson Texas Transportation Institute November 14, 2001
Objective • Define engineer’s role in designing, operating, and maintaining safe intersections.
Scope • Emphasis on the safety afforded motorists, pedestrians, and bicyclists at intersections.
Overview • Objective & Scope • Evidence of a Problem • Engineer’s Role • Engineering for Safety • Achieving a Safe & Efficient Intersection • What does the Engineer Need? • Closure
Evidence of a Problem • In 1999... • 25% of fatal crashes, • 50% of injury crashes, and • almost 50% of pedestrian injuries... ...were intersection-related.
Evidence of a Problem • In 1999... • nearly 10,000 people were killed and • about 1.5 million people were injured... ... at intersections.
Engineer’s Role • Mission - “The safe and efficient design, construction, maintenance, and operation of the roadway system...” (G.W. Black, ITE Journal, 12/98) • Goals – ITE Safety Action Plan • Promote best practices for traffic control devices • Promote best practices for design & illumination • Promote the use of crash data to identify problem intersections
Engineer’s Role • Goals – AASHTO Strategic Highway Safety Plan • Improve the design and operation of intersections • Upgrade signal controls to smooth traffic flow • Use new technologies to improve safety • Improve access management policies • NCHRP Project 17-18(3), CH2M Hill, MRI
Engineer’s Role • Challenges • Safety vs. efficiency • Uniformity vs. flexibility in design & operation • Proactive vs. reactive in addressing safety • Global vs. local scope of solution
Engineering For Safety • Problem Identification • Special users: older drivers, trucks, peds
Engineering For Safety Unsignalized Intersections • Design Solutions • separate traffic movements with bays • improve intersection sight distance • Traffic Control Solutions • flashing beacons at rural intersections • intersection lighting
Engineering For Safety Signalized Intersections • Design Solutions • curb-corner radius design • pedestrian refuge islands • Traffic Control Solutions • marked crosswalks • protected left-turn phase • intersection lighting
Achieving a Safe & Efficient Intersection Efficiency Combined Net Benefit Size Safety • Consideration of both safety and efficiency • Efficient operation does not insure safety 0 NCHRP Report 457
What Does the Engineer Need? • Institutional support, resources, training. • Better quality, more current, more readily available crash data (NCHRP Report 430). • Tools for estimating crash frequency and severity (e.g., IHSDM). • Formal safety evaluation process to yield uniform and consistent results.
Bibliography • The Traffic Safety Toolbox, ITE, 1999 • Manual of Transportation Engineering Studies, ITE, 1995 • Older Driver Highway Design Handbook, FHWA, 1998 HSDOG MUTCD Green Book
Closure • Evidence of a Problem • Engineer’s Role • Engineering for Safety • Achieving a Safe & Efficient Intersection • What does the Engineer Need?