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Roadway congestion can be caused by over saturation, poor weather, vehicle
crashes, work zones, poor signal timing, and special events. By integrating
communications and sensor infrastructure into the driving experience, cooperative
vehicle highway systems aim to mitigate congestion and increase overall system
performance, ultimately enhancing safety, mobility, emissions, fuel savings, and efficiency.
Ferlis: Our simulations have suggested we can get almost twice as
many vehicles through if there are -- all the vehicles and the infrastructure is
equipped with these technologies. Narr: in June of 2018, Federal Highway Administration
engineers, in cooperation with the Virginia Department of Transportation
and Transurban conducted connected and automated vehicle road tests on the
Interstate 95 reversible lane south of Washington, DC. The goal of the roadway
tests was to combine speed harmonization with connected automation technologies
such as platooning and cooperative merging on the managed lanes. Deans: The managed
lanes here are some of the most technology dense roads
in the world. So what that does is it creates a very safe environment to
operate it. So you're on a real road -- a real actual road, but no traffic, and if
you want real traffic or live traffic, we have microwave vehicle detectors out
there. We have AID cameras. We have fixed cameras. And so you're operating in
a very safe environment. Stanley: There's so many things that you don't realize when
you're in a controlled environment that you start to realize when you
interact with other vehicles and the unpredictability of the mixed
communication and automation environment. Narr: Through testing the team was able to
assess system performance of a particular scenario in which multiple
cooperative vehicle applications operate in parallel allowing for a vehicle to
merge behind a platoon that follows variable speed limits established by the
roadway operator. The speed harmonization application communicates with
infrastructure and roadway sensors continuously sending speed guidance
directly to the vehicle. McGhee: So one of the things that concerns us as owner-operators
is that all of these automated vehicles would be running around operating
independently. That connectivity layering allows us then some influence over the
behavior of that traffic. And if we can talk directly to the vehicle, then we can
have that vehicle slowed down in advance of a queue. We can ask it to change lanes
when we know a lane is closed for a crash or or a work zone. We can even alert
vehicles to the presence of workers in our roadway and improve safety in our
work zones. Narr: Platooning utilizes vehicle-to-vehicle communications to
share key parameters such as position, velocity, acceleration, and deceleration
with not only the cars immediately behind or in front of the vehicle but
throughout the platoon. The platooning algorithm then uses that information to
maintain consistent spacing and speed between all of the vehicles in the
platoon. Cooperative merging minimizes disturbances to mainline traffic by
adjusting the timing of vehicles entering the freeway.
Lab simulations run in preparation for this test found that as the number of
connected automated vehicles utilizing the cooperative applications increased,
roadway capacity significantly increased in the managed lane. The simulation also
showed that impacts of merging traffic can be reduced when cooperative merging
is combined with cooperative vehicles traveling in a platoon. Lastly, the
simulation showed that when speed harmonization is added, upstream traffic
is smoothed and more gaps between platoons are available to facilitate
cooperative merging. Ferlis: The next step is for us to take these research results and
encourage automotive manufacturers to further develop the technologies so that
they can produce commercial cars that consumers can buy and get the benefits.
Stanley: It's exciting to see the federal government working to develop a platform
to actually spur industry engagement in cooperative automation for the public
good. And so by developing this platform researching different use cases and
scenarios, it provides a foundation and research and identifying the validity
and value of this for private industry to
invest in, take it, and commercialize it. Narr: Roadway congestion will likely always be
with us in some form, but the era of building our way out of congestion
problems is waning quickly. Many of tomorrow's efficient roadways will not
be improved with bulldozers and graders, but with sensors algorithms and smart
roadways. The work of FHWA and its partners is pulling the future ever nearer.
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