Presentation on theme: "Problem : Unsafe Driving Behavior NHTSA Statistics: Driver distraction, inattention or drowsiness account for 20% of all crashes In 2008, 6000 people."— Presentation transcript:
Problem : Unsafe Driving Behavior NHTSA Statistics: Driver distraction, inattention or drowsiness account for 20% of all crashes In 2008, 6000 people died and approx ½ million were injured in crashes involving distractions Potential Countermeasures Behavioral Change: Safe driving habits – avoid using phones and other distractions In-vehicle Technology: Lane departure warning system
LDWS Functionality & Limitations Functionality Camera mounted on the screen detects: The location of the lane marking using marking retroreflectivity concept Vehicle’s relative position to the marking Unintentional lane change and alerts the driver Limitations LDWS performance depends on: Quality of the lane marking (retroreflectivity) Environmental conditions: day/night, dry/rainy etc
Field Test Tested LDWS performance (efficacy rate) on a 100 mile section along the FL Turnpike. Parameters considered: Marking types: thermoplastic single bead, double bead, tape etc Environmental conditions: day, night, rainy day, rainy night – with different rain intensities (light, moderate, heavy) Marking age (thru service life): 1 year, 2 years, 3 years Conclusions For typical marking (thermoplastic/tape) installations: On average - LDWS efficacy rate is close to 100% under daylight conditions for all rain intensities LDWS efficacy rate is significantly low (10% – 15%) under night time conditions for moderate and heavy rain LDWS performance drops with marking age.
Laboratory Test: TTI Rain Tunnel 1,600’ Rain Tunnel: Allowed us to test markings with high visibility during wet and rainy conditions at night. All weather markings Wet reflective markings Other high performance and durable markings Typical Service Life: Thermoplastic – 3 years Efficacy rate drops with age (see chart) Wet Reflective Tape – 6 years or more Efficacy rate = 100% throughout its service life
Factors affecting cost-effectiveness: 1.Service life of markings 2.Horizontal alignment 3.Highway type 4.Segment AADT value 5.Proportion of heavy vehicles 6.LDWS market penetration 7.Shoulder width 8.Proportion of crashes in rainy night conditions 9.Marking improvement alternative cost Cost of Severity: Fatality - $3,200,000 Injury - $74,730 PDO - $3,000 Cost of Severity: Fatality - $3,200,000 Injury - $74,730 PDO - $3,000 Unit Cost ($/ft): Thermoplastic: 0.50 Wet Reflective Tape: 2.5 Unit Cost ($/ft): Thermoplastic: 0.50 Wet Reflective Tape: 2.5 Crash Reduction Factors were estimated to calculate avoidable crashes for various scenarios; A spreadsheet tool was developed.
Cost Effectiveness Scenarios Alt1: Replace conventional thermoplastic pavement marking every 2 years Alt2: Replace conventional thermoplastic pavement marking every year Alt3: Use wet-reflective high performance pavement markings
Conclusion Pavement marking improvements (frequent replacement of conventional marking or installation of wet-reflective markings) can reduce ROR and lane change crashes for LDWS-equipped vehicles under rainy/night conditions. From B/C standpoint, improvements should be selected based on AADT, truck percentages, horizontal alignment, LDWS market penetration etc West-reflective tapes (service life – 6 years) were found to be most effective followed by frequent replacement (every 2 years) of conventional marking For a typical freeway segment, marking improvements become cost effective at 50% LDWS for freeway with 80,000 to 100,000 vpd; or 25% LDWS with almost double ADT Improvements at sharp-curve segments are most cost-effective