Presentation on theme: "Oklahoma’s Experience with Wire Rope Safety Fence."— Presentation transcript:
Oklahoma’s Experience with Wire Rope Safety Fence
In Oklahoma, median crossover accidents have increased. State Under Pressure In response to the increase in median crossover accidents, in 2006 ODOT initiated a program to install wire rope safety fence at critical locations through out Oklahoma.
First Installation in Oklahoma Lake Hefner Parkway Opened in 1991 6 lane divided highway approximately 44’ grass median; no highway lighting 108,000 ADT (2000) Speed limit 65 mph Site of 185 Crossover accidents – 6 Fatal, 77 injured from June 1, 1997 through May 31, 2001
Lake Hefner Parkway Considered three options: concrete median barrier, strong-post guardrail and cable barriers. Cost/mile for each option: Concrete median barrier: $500,000 Double-face W-beam guardrail: $105,000 Wire Rope Safety Fence-Socketed system: $84,000 Selected the Brifen wire rope safety fence with socketed system.
Brifen Wire Rope Safety Fence Background Developed by Brifen Ltd. in the United Kingdom in 1989 In use in over 30 countries and 1/2 of the states NCHRP-350 TL3 approved by FHWA in March 2001 Licensed Brifen USA, Inc. in November 2002 Picture 1 Picture 2 Picture 3
Brifen Wire Rope Safety Fence Features 10’-6” (3.2 m) Post Spacing Four Rope High Tensioned System Aesthetically Appealing Minimal Deflection Socketed System – Easy to Repair Capable of Long Segment Length Between Anchors Proven Crash Testing and Real World Experience
Brifen Wire Rope Safety Fence Application Center medians May be placed on either side of roadway Basic Design Criteria Recommend slopes of 6:1 or flatter Predictability of vehicle at impact with WRSF at normal height with all wheels still on ground Deflection less than 8 feet End anchors can be miles apart
Brifen Wire Rope Safety Fence Benefits Economical Installation Economical Installation Socketed Line Post System – Typical $15.95 LF Driven Line Post System – Typical $ 12.00 LF (Installed Costs) Low Occupant Ridedown Acceleration Low Occupant Ridedown Acceleration NCHRP-350 TL3 Maximum - 20 G’s Brifen 898 kg Car - 4.0 G’s Brifen 2000 kg Pickup - 2.86 G’s
Brifen Wire Rope Safety Fence Benefits (Continued) High Tensioned Prestressed Ropes High Tensioned Prestressed Ropes Reduced dynamic deflection Reduced length of barrier damaged in crash Secondary hits successful between repairs Low maintenance costs Wire Rope Safety Fence Open Design Wire Rope Safety Fence Open Design Visibility unobstructed through WRSF Debris blows through Fence Snow drift problem reduced Drainage unaffected by Wire Rope Safety Fence
Brifen Wire Rope Safety Fence Oklahoma City, OK - Lake Hefner Parkway 1000 Linear Feet Installation in September 2000 7 Mile Installation in July 2001 Picture 1 Picture 2 Picture 3
Brifen Wire Rope Safety Fence Lake Hefner Parkway Specifics Wire Rope Safety Fence installed in median 2 feet from existing southbound shoulder Asphalt widening under WRSF for weed barrier Seven miles in length
Accident History— 2001 to 2006 Since 2001, over 430 hits. In 2/3 of those hits, driver kept going.Since 2001, over 430 hits. In 2/3 of those hits, driver kept going. Injuries: Injuries: Reduced from 77 injuries in 2001 to 8 injuries in 2006. Fatalities: Fatalities: Reduced from 6 fatalities in 2001 to 1 fatality in 2006.
Brifen Wire Rope Safety Fence Socketed System Typical repair time under 30 minutes Only one person required No specialized tools (except tension meter on occasion) No lane closures required for heavy equipment Inexpensive – normally just a few posts There has been no damage to ropes or rigging screws in over 430+ impacts Picture 1Picture 2
I-35 in Norman: I-35 in Norman: Prior to wire rope safety fence installation: Prior to wire rope safety fence installation: 7 fatalities, 39 injured (3 years) 7 fatalities, 39 injured (3 years) Since installation (2005): NO fatalities, NO injuries. 140+ hits and several semi hits. Since installation (2005): NO fatalities, NO injuries. 140+ hits and several semi hits. Installed in the center of the median; required a 6:1 slope or flatter; adjustments to the median drainage structures. Installed in the center of the median; required a 6:1 slope or flatter; adjustments to the median drainage structures.