Oklahomas Experience with Wire Rope Safety Fence

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Oklahomas Experience with Wire Rope Safety
Fence
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• 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.

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First Installation in OklahomaLake 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

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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.

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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

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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

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Brifen Wire Rope Safety Fence Application

• Center medians
• May be placed on either side of roadway
• Basic Design Criteria
• Recommend slopes of 61 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

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Brifen Wire Rope Safety Fence Benefits

• Economical Installation
• Socketed Line Post System Typical 15.95 LF
• Driven Line Post System Typical 12.00 LF
• (Installed Costs)
• Low Occupant Ridedown Acceleration
• NCHRP-350 TL3 Maximum - 20 Gs
• Brifen 898 kg Car - 4.0 Gs
• Brifen 2000 kg Pickup - 2.86 Gs

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Brifen Wire Rope Safety Fence Benefits
(Continued)

• 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
• Visibility unobstructed through WRSF
• Debris blows through Fence
• Snow drift problem reduced
• Drainage unaffected by Wire Rope Safety Fence

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Brifen Wire Rope Safety Fence

• Oklahoma City, OK - Lake Hefner Parkway
• 1000 Linear Feet Installation in September 2000
• 7 Mile Installation in July 2001

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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

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Accident History2001 to 2006

• Since 2001, over 430 hits. In 2/3 of those hits,
  driver kept going.
• Injuries
• Reduced from 77 injuries in 2001 to 8
  injuries in 2006.
• Fatalities
• Reduced from 6 fatalities in 2001 to 1 fatality
  in 2006.

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Brifen Wire Rope Safety Fence Lake Hefner
Parkway Photos
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Brifen Wire Rope Safety FenceLake Hefner Parkway
Impacts
August 1, 2001 To December 1, 2002
Total Impacts 141 Total Posts
665 Avg Posts/Impact 4.71
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Brifen Wire Rope Safety FenceLake Hefner Parkway
Impacts
August 1, 2001 To December 1, 2002
Northbound Impacts 44
Posts 200 Average
4.54 Southbound Impacts
97 Posts 465 Average
4.79
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Brifen Wire Rope Safety FenceLake Hefner Parkway
More Impacts
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Brifen Wire Rope Safety FenceLake Hefner Parkway
More Impacts
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Brifen Wire Rope Safety FenceTypical Vehicle
Damage
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Brifen Wire Rope Safety FenceTypical Vehicle
Damage (Continued)
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Brifen Wire Rope Safety FenceSocketed 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

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Brifen Wire Rope Safety FenceSocketed Option
Easy Repair
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• I-35 in Norman
• Prior to wire rope safety fence installation
• 7 fatalities, 39 injured (3 years)
• Since installation (2005) NO fatalities, NO
  injuries. 140 hits and several semi hits.
• Installed in the center of the median required a
  61 slope or flatter adjustments to the median
  drainage structures.

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10 minutes, no re-tensioning