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(ambient music)

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- [Narrator] Guardrails are an important

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and cost-effective safety feature
along high-speed roadways,

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shielding passenger and freight vehicles

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from roadside hazards.

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The end transition piece of the guardrail

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is very important to the overall safety

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because its purpose is
to lessen the severity

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of vehicle collision
with the guardrail end.

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The Texas Department of Transportation

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supports research and development
of continuous improvements

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and innovations to the guardrail systems

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in place across the state.

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The Texas A&M Transportation Institute

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developed a MASH TL-4 compliant
guardrail system in 2021

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and has now completed the design

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and full-scale crash
testing of an end transition

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for the TL-4 guardrail system,

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making it ready for full implementation.

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- Guardrails that you see
on the side of the roads

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prevent vehicles from
getting off the road.

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They do that to prevent them
from striking an object,

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or crossing over to the other side,

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or rolling over on a ditch.

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The standard guardrail that
you see on the side of the road

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is designed for passenger vehicles.

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There are others that are
designed for freight vehicles.

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So, like a single-unit
truck or a tractor-trailer.

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- There are locations that will have

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a higher percentage of trucks.

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And, so, a TL-4 system is actually

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a 22,000-pound delivery
truck at 56 miles per hour.

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So, it's a more rigorous system

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to prevent collapse of a guardrail

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or whatever other type of
roadside safety hardware

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might be used if it's
hit by a larger vehicle.

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We were looking at the
transition from the TL-4 system,

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which is, I believe, 40 inches high,

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down to the standard metal
beam guard fence system

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because you need a transition

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because there's not
necessarily an attenuator

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or something that's gonna be compatible

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with the TL-4 system.

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So, you have the TL-4 system,
which would be applied.

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Then you have a transition:
about a 25-foot transition,

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down to the standard metal
beam guard fence system,

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which is TL-3.

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And that way, you can utilize the system

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where you think there's
the greatest likelihood

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that it might be impacted
by a larger truck.

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- For this research, we came
up with different concepts

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of taking the shape of
the test level 4 guardrail

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and morphing it gradually
to your standard guardrail.

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It was done here at TTI

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in the roadside safety and
physical security division.

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We came up with different concepts.

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Then, we simulated some of those concepts

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using finite element simulations.

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In those simulations, we looked
at different impacts from,

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you know, small car and a pickup truck

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striking in different directions.

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And we were trying to assess the safety

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of that transition
portion of the guardrail.

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We did a lot of iterations on the design,

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the initial concepts that we had,

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until we came up with something

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that we felt was worthy of testing,

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and we felt good about it
working well in crash testing.

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We performed two tests.

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Both of those tests work
very nicely, and as a result,

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we have a very nice transition design.

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- [Kenneth] There are a
lot of trucks in Texas,

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and for areas that we want to provide

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a greater degree of protection
with high-percentage trucks

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in maybe a more economical way,

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this system will be very
beneficial in that area.

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- [Narrator] For more information

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and to find the publication
for this project,

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please visit the TxDOT Research Library

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at the link shown below.