Cable Guardrail

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Cable Guardrail in Kentucky, 2006
Jeff Jasper Division of Highway Design Kentucky
Transportation Cabinet
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Todays Presentation

• What is Cable Guardrail?
• Cable Guardrail as a Median Barrier in Kentucky?
• Future Prospects?

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What is Cable Guardrail?
Answer A barrier system which consists of steel
cables mounted on weak posts.
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What is Cable Guardrail?
Several variations have been successfully crash
tested. Cable guardrail has been successfully
utilized as a roadside barrier and (most
extensively) as a median barrier.
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What is Cable Guardrail?
The cable guardrail barrier redirects impacting
vehicles after sufficient tension is developed in
the cable, with the posts in the impact area
offering only slight resistance.
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What is Cable Guardrail?

• Primary advantages
• Low initial cost
• Effective vehicle containment
• Designed to facilitate quick and easy repairs
• Used with median cross-slopes as steep as 61
• Low deceleration forces upon the vehicle and
  its occupants

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Typical Vehicle Damage
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What is Cable Guardrail?

• Primary disadvantages
• Must accommodate deflection distances
• Damage expected even with moderate impacts
• Require maintenance after every impact
• May require periodic inspections
• Vehicles can pass under the rail system

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Cable Guardrail as a Median Barrier in Kentucky
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Cable Guardrail as a Median Barrier in Kentucky
Nationwide, the severity and frequency of
cross-median crashes has increased in recent
years, primarily due to more traffic, higher
speeds, heavier vehicles, and increased
aggressive driver behavior.
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Cable Guardrail as a Median Barrier in Kentucky
According to KY CRASH data, from 2000 to 2005
there have been 467 cross-median crashes in
Kentucky, which caused 117 deaths and 562
injuries.
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2005 KY CRASH data Total fatalities median
cross over fatalities
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Cable Guardrail as a Median Barrier in Kentucky
A series of three median cross-median crashes
over a 3-week period in the Louisville area
elevated the awareness of the issue.
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Snyder crash kills 3 students Collision blamed
on tire blowout
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Snyder crash kills 3 students Collision blamed
on tire blowout
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Snyder crash kills 3 students Collision blamed
on tire blowout
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Snyder crash kills 3 students Collision blamed
on tire blowout
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Cable Guardrail as a Median Barrier in Kentucky
In the Fall 05, KYTC initiated design of two
Median Barrier Safety pilot projects in Jefferson
County.
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Cable Guardrail as a Median Barrier in Kentucky
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• Wire Rope Safety Fence TL-4

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Cable Guardrail as a Median Barrier in Kentucky
The construction of these pilot projects will
begin in Spring 06. (NOW!)
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Cable Guardrail as a Median Barrier in Kentucky

• What we hope to learn from our pilot projects
• Guidelines for median cable barrier placement
• Strategy to maintain monitor
• Economics of use

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Future Prospects?
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Future Prospects
Future Projects
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But where? And how much? ?
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What we know.

• Many cross-median crashes occur on medians over
  30 feet wide
• Median encroachments are likely to increase with
  higher traffic volumes
• Cross-over crashes are severe
• Median barriers can significantly reduce cross
  over crashes
• Barrier selection and placement are critical for
  optimal performance

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What we dont know

• What median width/ADT combinations result in
  cost-effective warrants?
• How should crash history be considered?
• When will new warrants be adopted by AASHTO?

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Cable Guardrail as a Median Barrier in Kentucky
Foreseeable Future Plans to make. Work to do.
Lives to save.
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Cable Guardrail as a Median Barrier in Kentucky
GIT-R-DONE!!! I'll see ya'll down the road.
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• Questions?