>> GREG JOHNSON: "Median cable guardrail has saved lives
on numerous occasions by deflecting those folks and keeping them out of oncoming traffic lanes."
>> NARRATOR: Cable median barrier is expected to save 13 lives and prevent 51 incapacitating injuries this year alone.
In this presentation, the Michigan Department of Transportation would like to present a preview on cable median barrier
and how, as a first responder, you can operate safely and efficiently around the new system.
This presentation is intended only for first responders.
What is cable median barrier?
Cable median barrier consists of steel ropes mounted on steel posts.
These posts sit in a steel sleeve, cast in a concrete foundation.
Cable median barrier is a low-cost system designed to prevent vehicles from crossing the median.
Why is the Michigan Department of Transportation choosing to use cable median barrier?
It is proven to be 95 percent effective after an impact in reducing crashes with serious injuries
when compared to standard steel guardrail and concrete barrier wall-type systems.
The cable median barrier system remains partially effective
if the cables are still intact after an initial impact.
This system is easier to repair in most instances with the removal and replacement of the posts.
Nationally, it is estimated to replace approximately four to six posts per typical impact to the system.
It is a lower cost system to install versus standard guardrail and concrete barrier wall.
Our estimates show that cable median barrier is $12 to $15 per linear foot to install,
while steel guardrail runs $28 per foot to install.
Where is MDOT putting cable median barrier?
We are aiming for medians with an existing crossover crash history.
The barrier system is ideal in locations where we cannot meet the design warrants for other median barrier wall types.
This includes our standard steel guardrail and our concrete barrier wall systems.
We are targeting medians with widths of 100 feet or less.
This is where we tend to see most of our crossover crashes.
We are installing these systems on a 1-on-4 slope or flatter.
Installing the system on these slopes supports the relatively low cost of the system
by preventing the need to grade and flatten the median.
By the end of 2011, statewide, MDOT plans to have more than 290 miles of cable median barrier in place
along it’s 10,000-plus mile route system.
This video, by Gibralter Systems, demonstrates how the cable system works
by showcasing the testing required to approve the cable median barrier system.
The Michigan Department of Transportation has approved five cable median barrier systems within its inventory:
Brifen, Cass, Safence, Gibralter and NuCable.
The next several photos show the different systems and covers briefly
how they are different from each other.
The Brifen system, manufactured by Brifen USA, has three to four weaving cables.
You can see in the photo that this system has two cables that run through the center of each post
and two cables that weave between posts.
The Cass Cable systems, manufactured by Trinity Industries in Gerard, Ohio,
is a three-cable system where all three cables travel through the center of each post.
The Safence cable system, manufactured by Safence Inc., uses either a three- or four-cable system.
Again, all cables are in line and travel through the center of each post.
The Gibraltar Cable system, manufactured by Gibraltar LLC in Bernet, Texas, uses both a three- and four-cable system.
It has a hairpin design, as shown in this photo, that allows the cables to run straight but alternate on sides of the posts.
The NuCable system, manufactured by NuCore Steel Marion, in Marion, Ohio,
uses a three-cable system that also applies the hairpin design
that attaches to the post and allows the cable to run straight.
Note how the cable runs on the same side of each post.
When working with cable median barrier systems, remember safety first.
It is critical to make sure that people are clear of the area
and the vehicles that are entangled by the system.
On a typical impact, no lane closures are necessary to retrieve a vehicle from the system.
Heavy equipment or special tools are not required to remove a vehicle.
In extreme conditions, the cable can be laid down and driven over in an emergency-type situation.
The next several screens recommend methods to aid in extracting a vehicle from the cable system.
First, for ease in removing a vehicle,
create slack in the system by removing the posts near the impact location.
In the winter, there may be ice in the sockets that can prevent the posts from sliding out of the sleeve easily.
Our maintenance personnel are equipped with the tools necessary to assist in the removal of posts from the ice.
Depending on the system, the hairpins also may be removed or separated from the posts.
Remember, MDOT maintenance staff can help you release tension on the system.
They are our experts in the field, working with the system and making the repairs in the field.
They can be on hand to assist in the extraction of the vehicle from the system.
Please contact your local maintenance garage for information.
Another technique to remove the vehicle is to remove the vehicle in the same direction it entered the system.
Lastly, release cable tension by loosening a turnbuckle between two upright posts.
The turnbuckles are located approximately 1,000 feet apart and they connect two pieces of cable.
Each turnbuckle has two inspection holes.
Before loosening the turnbuckle, it is important to verify the presence of the cable in the inspection hole.
If the cable is under tension, never loosen the cable past the inspection hole in the turnbuckle.
Only as a last resort, cut the cable under tension.
This is important for the safety of everyone at the impact area.
To demonstrate this, a group of Minnesota first responders took it upon themselves to record the effects of cutting the cable.
The first video shows a cable under tension at approximately 9,300 pounds.
The cable is cut between two upright posts.
Once this cut is made, you can see that the cable retracts approximately 15 to 20 feet in each direction,
controlled by the upright posts.
The second video utilizes an excavator with a bucket to imitate an impact to the cable system by removing the posts,
realigning the cable and placing directional forces against the system.
This first responder cuts the cable in a location not controlled by two upright posts.
Notice that the cable whips around the excavator bucket and toward the impact area.
It is very important that when a cable is cut, the entire area is clear of people.
If it is necessary to cut the cable, it is recommended that this cut be made between
two upright posts and at the nearest turnbuckle.
Since there are several alternatives to releasing tension in the system,
it is recommended that the cable be cut only under life and death situations.
Any other cuts to the cable system must be in coordination and guidance with MDOT personnel.
So to summarize, if a cable must be cut, make sure that all personnel,
except the person cutting the cable, are clear of the system.
Cut the cable between two upright posts for controlled retraction.
Cut the cable at the nearest turnbuckle between two upright posts, away from the area of the impact.
Remember the cable may react differently when cut,
due to the five different designs approved for use in the state of Michigan.
When cut, the entire cable and system may be ineffective until repaired.
Cable splicing may be required, which will extend the duration that the system is out of commission.
Up to a 1,000 feet of cable may need to be replaced, if the cut does not occur at a turnbuckle.
With your help and attention, cable median barrier is expected to save 13 lives
and prevent 51 incapacitating injuries each year.
Thank you for your time and cooperation.
More information on the cable barrier system can be found at the MDOT Web site.