(dramatic music)
- [Narrator] Super 2 highways have been in use across Texas
for over two decades, offering a cost-effective way
to improve safety and traffic flow on rural two-lane roads.
Early research has shown these roadways do increase safety,
but with traffic increasing
and more Super 2s being built,
a more up-to-date analysis was needed.
The Texas Department of Transportation
and researchers with the Texas A&M Transportation Institute
have examined recent data
to update the crash modification factor,
quantifying the safety benefits of Super 2 highways.
- So these lanes allow faster-moving vehicle
to pass slower vehicle,
and the result is improved traffic flow and also safety.
So we needed some evidence-based or data-driven criteria
to help us in this selection and justification
of using Super 2.
- This project allowed us to take a more detailed look
at the safety benefits
and actually develop a crash modification factor, or a CMF,
and actually a series of them, as it turns out,
so the TXDOT could use that in their support
for future Super 2 implementation.
We were able to look at a lot of locations across the state.
In fact, we looked at 67 different Super 2 corridors,
and then 165 segments of other two-lane highways
that have similar characteristics, but no passing lanes.
And we reviewed all of these through the databases
that were available.
We also used aerial photography
and some other in-office resources
as well as the crash databases that TXDOT provides
that we were able to access
to get a detailed look at the crash history
of each of these sites that we looked at,
and then conduct the statistical analysis
to produce the results.
Super 2s do have a positive benefit on safety,
and the numbers bear that out as statistically significant,
result of 21% reduction in total crashes
compared to your traditional two-lane highways.
- The finding of this study,
we assumed that it will enhance the knowledge,
overall knowledge, to improve the overall design
and the highways for infrastructure within Texas,
and really, across the United States.
- This provides that extra support
in that not only do they improve the operational performance
by allowing people to pass, reducing congestion,
reducing travel time, et cetera,
but this safety performance helps us know for sure
that they do, in fact, have an effect on reducing crashes,
and so it's showing that those passing lanes
are doing what they're intended to do.
And so TXDOT can continue to use these
and roll them out across the state with confidence.
And this provides one more way to do that.
- [Narrator] For more information
and to find the publications for this project,
please visit the TXDOT Research Library
at the link shown below.