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An experiment at the Massachussetts Institute of Technology has
highlighted some of the hidden risks inherent in (supposedly) smart cars
that will depend on radio-based Intelligent Transport Systems (ITS) for
extra safety on the road.
In an ITS system, in-car computers communicate with each other over
vehicle-to-vehicle (V2V) microwave radio links, while the cars also
communicate with traffic lights and roadside speed sensors over a
vehicle-to-infrastructure (V2I) radio signalling system (the
infrastructure transmits information about cars that are too old to have
ITS systems fitted). When two cars are approaching a junction and the
V2V/V2I speed signals suggest they are going to crash, a warning can be
sounded or a software algorithm can choose to make one of the cars
brake, for instance.
I tried this out on the Millbrook test track in Bedfordshire, UK, in
2007: speeding towards a junction in a Saab my brakes were automatically
applied to allow a speeding Opel to pass in front of me. It was by turns
scary and impressive. But if it hadn't worked I'd have been toast.
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But MIT engineer Domitilla Del Vecchio says such systems can be
over-protective, taking braking action when there is no real threat.
"It's tempting to treat every vehicle on the road as an agent that's
playing against you," she says in an MIT research brief issued today.
So she and researcher Rajeev Verma set out to design an algorithm that
doesn't over-react - and to test it with model vehicles in a lab. Their
trick was simple: calculate not speed but acceleration and deceleration
as cars approach a junction, allowing a much finer calculation of the
risk. In 97 out of 100 circuits, the collision avoidance technology
worked fine.
But in three cases, there were two near-misses and one collision. The
reason? Nothing to do with the algorithm: it was due to delays in V2V
and V2I radio communication. This highlights the risk of depending upon
a complex safety system like ITS - especially a radio-based one which
could easily be jammed or electromagnetically interfered with because of
the wireless technologies which proliferate in our built environment.
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There is only so much that researchers can
do against a phenomenon as difficult to predict as radio interference.
The takehome message? ITS technology will doubtless do much to
improve road safety - but sometimes it won't. It's never going to
substitute for driver alertness.
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