High Tension Cable Median Barrier

1. High Tension Cable Median Barrier March 17, 2011

2. Cross median crashes • Cross median crashes are 3 times more deadly than other types of crashes. • A vehicle travelling at highway speeds can cross a 36’ to 50’ median into oncoming traffic in the time it takes to: • Change the radio station • Answer a cell phone • Yawn

3. Cross Median Crashes • Difficult to solve • No specific time of day, week, month or year • Take place on vertical and horizontal curves as well as straight and flat sections of roadway • Various causes • Fatigue • Improper lane changes • Inattention • Medical Emergencies

4. Patterns Emerging • Entrance and exit ramps that lead to weaving maneuvers • Changes in the number of lanes • Median cross sections

5. Good News • Research has shown that protective barrier can prevent most cross median crashes, regardless of the circumstances. • Goal of Cable median barrier: Contain vehicles in the median once they leave the roadway where they are less likely to involve other vehicles and cause a multi-vehicle crash.

6. Definition • Cable median barrier is 3 or 4 steel cables, tensioned and strung on posts. Office of Traffic, Safety and Technology

7. Benefits of Cable Median Barrier • Most versatile and forgiving barrier system available for reducing the severity of run-off-road crashes. • When struck • Posts break • Cables flex • Absorbs most of the crash’s kinetic energy • Redirects the vehicle along the barrier • National studies have shown a 96% reduction in fatal cross median crashes. Office of Traffic, Safety and Technology

8. Benefits of Cable Median Barrier • Can be installed on a slope • 4:1 or flatter • Farther away from the traveling public • Show a substantial reduction in fatal and injury crashes when compared to concrete and metal beam barriers • Low installation costs Office of Traffic, Safety and Technology

9. Minnesota Examples Office of Traffic, Safety and Technology Video 1

10. Multiple Hits Office of Traffic, Safety and Technology Video 2

11. Placement in Median Major factors to consider are: • FHWA and NCAC (National Crash Analysis Center) guidance • Median configuration (slopes, width, depths, etc) • Future adjacent roadway projects • Maintenance Office of Traffic, Safety and Technology

12. FHWA and NCAC Guidance • FHWA Approval Letters • “V- ditches” • Approved 0- 4’ down the 1:4 fore slope with >9-10’ from the ditch bottom • Most of our median ditches are: • Trapezoidal ditches • 1:4 foreslope • Average depth of 2’

13. National Crash Analysis Center (NCAC) Modeling and Simulation • Over 80 modeling and simulations were completed

14. Median Placement Criteria • Direction of majority of lane departures • Place cable on opposite side of median • Computer models • Place as far from the travelling public as possible • Keep within 6 feet of top of side slope • Avoid the middle of the median • Soil Conditions • Maintenance

15. Placement In Median Video 3 Office of Traffic, Safety and Technology

16. Cable Median Installations • Minnesota Data • 260 miles installed to date • 90-100% Reduction in target K&A’s • Additional 90 miles planned

17. Study Details • MN’s first 75 miles installed • 2004, 2005, 2006 and 2007 • 24 fatal crashes in the 3 years prior to installation • 13 fatalities were “target” crashes • Run off road left • Head on • Sideswipe opposing • 0.75 miles were excluded from the study because of inaccurate reference points Office of Traffic, Safety and Technology

18. Study Results Office of Traffic, Safety and Technology

19. Crash Costs • Fatality (K) = $7,100,000 • Incapacitating (A) = $415,000 • Nonincapacitating (B) = $137,000 • Possible (C) = $91,000 • Property Damage (PD) = $12,000 Source: Mn/DOT Office of Capital Programs and Performance Measures (July 2010) Office of Traffic, Safety and Technology

20. Study Results • Property Damage Costs = $5,640,000 • 470 more property damage crashes after (632-162) • Fatal Crash Costs = $92,300,000 • 13 fewer Fatalities after Office of Traffic, Safety and Technology

21. Crash Costs • 1 Cross median fatality where cable median is installed (unrestrained driver) • 1 life saved for every 17 miles of installed cable median (annually) • 77 lives saved to date Office of Traffic, Safety and Technology

22. Minnesota Examples Office of Traffic, Safety and Technology

23. Minnesota Examples Video 4 Office of Traffic, Safety and Technology

24. Maintenance • Cable Placement • Out of the center of median • Shoulder placement • Remove turn buckles rather than cut cable • Spaced approx. 1000’ • Each installation approx. 1 mile in length • 5 Opportunities to loosen cable per installation • Cable cannot be re-spliced • Maintenance can take up to 6 weeks Office of Traffic, Safety and Technology

25. Extrication Difficulties Office of Traffic, Safety and Technology

26. Maintenance Training • How to get slack in cable • Manipulate cable (tow service) • Posts – take out or cut • Turnbuckle • Loosen • Remove • Cut • Spreader Bar • For woven systems • $300 from manufacturer Office of Traffic, Safety and Technology

27. Maintenance Training • Stock piles of parts • Multiple shops • Multiple manufacturers • Steamers to remove posts in ice • Training video on cutting cable • Communication • First responders • Maintenance • Design • Location of turn-arounds Office of Traffic, Safety and Technology

28. Minnesota Links • MN Office of Traffic, Safety, and Technology (OTST) • http://www.dot.state.mn.us/trafficeng/safety/index.html • Solicitations • Greater MN & Metro Announcements & Applications • http://www.dot.state.mn.us/trafficeng/safety/hes/index.html Office of Traffic, Safety and Technology

29. Contact Information • Julie Whitcher • 651-234-7019 • Julie.Whitcher@state.mn.us • MN Office of Traffic, Safety, and Technology (OTST) • http://www.dot.state.mn.us/trafficeng/safety/index.html Office of Traffic, Safety and Technology