Federal Highway Administration Department of Transportation Effective Lateral Placement of Cable Barriers in Flat-Bottom, Sloped Medians Dr. Dhafer Marzougui NCAC, George Washington University Ashburn, VA under contract to Offce of Safety R&D Turner Fairbank Highway Research Center Federal Highway Administration McLean, VA

Federal Highway Administration Department of Transportation Introduction: Cross median crashes have grown to be a serious problem Cable median barriers offer an option to mitigate the problem Many DOTs are installing cable barriers because of: olow costs oease of installation oadaptability for sloped conditions Research has shown that effectiveness is related to: obarrier design (number & height of cables, tensioning) oconfiguration of the median (shape, width, slopes, depth) olateral position Objective - evaluate vehicle-to-barrier interface for placement in flat-bottomed medians with varying widths and side slopes

Federal Highway Administration Department of Transportation Vehicle Dynamics Analysis: Point 2. Point 1.

Federal Highway Administration Department of Transportation Research Factors & Assumptions: Vehicle Models: -2000P - 820C - Mid-size Sedan Shoulder Median Median Barrier Near Side Impact Far Side Impact Initial Speeds: 50, 70, 100 km/hr Approach Angles: 5 to 25 deg 5 o 25 o

Federal Highway Administration Department of Transportation Simulation Assumptions: Median has firm surface. Ploughing into the surface by tires is negligible Non-tracking vehicle paths were not considered Initial velocity was assigned to vehicle as it left the shoulder. Some deceleration occurred crossing the median. No driver reactions (e.g., steering, braking) Vehicle full-engagement with a minimum of one cable is needed to capture vehicle

Federal Highway Administration Department of Transportation Validation: Comparisons of Simulation to Crash Test Results

Federal Highway Administration Department of Transportation Effective Interface Conditions: To avoid over-ride, the top cable should contact the vehicle above Point 1 (lower critical point) To avoid under-ride, lower cable should contact the vehicle below Point 2 (upper critical point) These conditions should be met for all approach angles, speeds, and different vehicles Point 2 Point 1

Federal Highway Administration Department of Transportation Point 1 Trajectories – All Cases & Maximums:

Federal Highway Administration Department of Transportation Point 2 Trajectories – All Cases & Minimums:

Federal Highway Administration Department of Transportation Maximum and Minimum Heights Override Limit Underride Limit

Federal Highway Administration Department of Transportation Effective Lateral Placement: (10:1 slopes – 36’ width not including shoulders – generic 3 cable)

Federal Highway Administration Department of Transportation Effective Lateral Placement: (10:1 slopes – 36’ width including shoulders – generic 3 cable)

Federal Highway Administration Department of Transportation Evaluating Flat Bottom Median Profiles: Median Widths ft Slopes 8:1, 6:1, 4:1 Shldr 10 ft Widths 25, 40, 60, and 100 ft Slopes 4:1, and 6:1 Shldr 2ft4ft6ft Analyzed varied flat-bottomed median profiles: - Median width (25, 40, 60, & 100 ft) - Median depth (2, 4, & 6 ft) - Median slopes (4:1 and 6:1) Vehicle dynamics simulations were conducted for each combination of these factors.

Federal Highway Administration Department of Transportation Cable Barrier Systems Considered: Brifen System Cable heights o480 mm (18.9 in) o630 mm (24.8 in) o780 mm (30.7 in) o930 mm (36.6 in) Gibraltar System Cable heights 508 mm (20 in) 635 mm (25 in) 762 mm (30 in) 990 mm (39 in)

Federal Highway Administration Department of Transportation I-694 Medians

Federal Highway Administration Department of Transportation I-694 Section A Median Profile

Federal Highway Administration Department of Transportation I-694 Section A Median Profile Median Widths ft Slopes 8:1, 6:1, 4:1 10 ft 51 ft Slope 6:1 3ft 15 ft 51 ft Slope 6:1 4ft 3 ft Two profiles were analyzed to account for depth variation

Federal Highway Administration Department of Transportation I-694 Section A Median Profile

Federal Highway Administration Department of Transportation I-694 Section A Median Profile

Federal Highway Administration Department of Transportation I-694 Section B Median Profile

Federal Highway Administration Department of Transportation I694 Section B Median Profile 51 ft Slope 10:1 2.5ft 1 ft

Federal Highway Administration Department of Transportation I694 Section B Median Profile

Federal Highway Administration Department of Transportation I-35W Profiles

Federal Highway Administration Department of Transportation I-35W Section A Median Profile

Federal Highway Administration Department of Transportation I-35W Section A Median Profile Median Widths ft Slopes 8:1, 6:1, 4:1 10 ft 33 ft Slope 4:1 2.5 ft 13 ft 33 ft Slope 4:1 3.5 ft 5 ft Two profiles were analyzed to account for depth variation

Federal Highway Administration Department of Transportation I-35W Section A Median Profile

Federal Highway Administration Department of Transportation I-35W Section A Median Profile

Federal Highway Administration Department of Transportation I-35W Section B Median Profile

Federal Highway Administration Department of Transportation I35W Section B Median Profile Median Widths ft Slopes 8:1, 6:1, 4:1 10 ft 49 ft Slope 4:1 2.5 ft 29 ft 49 ft Slope 4:1 3.5 ft 21 ft

Federal Highway Administration Department of Transportation I-35W Section B Median Profile

Federal Highway Administration Department of Transportation I-35W Section B Median Profile

Federal Highway Administration Department of Transportation I-35W Section C Median Profile

Federal Highway Administration Department of Transportation I-35W Section C Median Profile Median Widths ft Slopes 8:1, 6:1, 4:1 10 ft 29 ft Slope 4:1 2.5 ft 9 ft 29 ft Slope 4:1 3.5 ft 1 ft

Federal Highway Administration Department of Transportation I-35W Section C Median Profile

Federal Highway Administration Department of Transportation I-35W Section C Median Profile

Federal Highway Administration Department of Transportation TH-13 Profiles

Federal Highway Administration Department of Transportation TH 13 Section A Median Profile

Federal Highway Administration Department of Transportation TH 13 Section A Median Profile Three profiles were analyzed to account for width variations

Federal Highway Administration Department of Transportation TH 13 Section A Median Profile – 28’ width

Federal Highway Administration Department of Transportation TH 13 Section A Median Profile – 35’ width

Federal Highway Administration Department of Transportation TH 13 Section A Median Profile – 42’ width

Federal Highway Administration Department of Transportation TH 13 Section B Median Profile No analyses performed (3:1 sloped section)

Federal Highway Administration Department of Transportation TH 13 Section C Median Profile

Federal Highway Administration Department of Transportation TH 13 Section C Median Profile Two profiles were analyzed to account for width variations

Federal Highway Administration Department of Transportation TH 13 Section C Median Profile – 18’ width

Federal Highway Administration Department of Transportation TH 13 Section C Median Profile – 25’ width

Federal Highway Administration Department of Transportation TH 13 Section D Median Profile

Federal Highway Administration Department of Transportation TH 13 Section D Median Profile One profiles was analyzed

Federal Highway Administration Department of Transportation TH 13 Section D Median Profile – 20’ width

Federal Highway Administration Department of Transportation TH-55 Profiles

Federal Highway Administration Department of Transportation TH 55 Section E Median Profile

Federal Highway Administration Department of Transportation TH 55 Section E Median Profile Three profiles were analyzed to account for width variations

Federal Highway Administration Department of Transportation TH 55 Section E Median Profile – 23’

Federal Highway Administration Department of Transportation TH 55 Section E Median Profile – 28’ width

Federal Highway Administration Department of Transportation TH 55 Section E Median Profile – 31’ width

Federal Highway Administration Department of Transportation TH 55 Section F Median Profile

Federal Highway Administration Department of Transportation TH 55 Section F Median Profile Two profiles were analyzed to account for width variations

Federal Highway Administration Department of Transportation TH 55 Section F Median Profile – 23’ width

Federal Highway Administration Department of Transportation TH 55 Section F Median Profile – 31’ width

Federal Highway Administration Department of Transportation TH 55 Section G Median Profile

Federal Highway Administration Department of Transportation TH 55 Section G Median Profile Six profiles were analyzed to account for width variations

Federal Highway Administration Department of Transportation TH 55 Section G Median Profile – 24’ width

Federal Highway Administration Department of Transportation TH 55 Section G Median Profile – 30’ width

Federal Highway Administration Department of Transportation TH 55 Section G Median Profile – 40’ width

Federal Highway Administration Department of Transportation TH 55 Section G Median Profile – 50’ width

Federal Highway Administration Department of Transportation TH 55 Section G Median Profile – 60’ width

Federal Highway Administration Department of Transportation TH 55 Section G Median Profile – 100’ width