Intelligent Transport Systems - Telenor

6
Sensor
Figure 3 Road with
electronic fence
Figure 4 Internet along
the Autobahn
Anti-collision radar
Computerised systems can be made much safer
than systems run by computers. The machine is
only thinking about performing the tasks defined
in the software programs; it is not subject to
diversions, disturbances or distractions that can
take the human attention away from the road
long enough to cause an accident. Nevertheless,
most of us prefer a human being to be in charge
of the airplane, train or bus we enter – we feel
safer that way though (except for the bus) this is
an illusion. We never reflect the fact that on
most of the route the autopilot steers the plane –
on many airports even the landing is automatic
and conducted by computers, and that computers
are in charge of the TGV, the Shinkansen and
other extremely fast train. In order to illustrate
our belief in human infallibility the Space Shuttle
of NASA was automatic except for lowering
the landing wheels of the shuttle at re-entry into
the atmosphere [7]. This was by far the most
dangerous activity during the whole mission!
A simple and practical way in which we can
start exploring automatic driving is the following
one. In Japan they are planning the introduction
of this system.
Again we put sensors in each lane and let the car
trace the sensors. However, the driver can over-
rule the automatics in order to change direction
at road crossing or to leave the road. Then we do
not need to develop, maintain and operate all the
complex algorithms and software of the driverless
car. In this system, the sensors form an electronic
fence between lanes, and the software in
the vehicle is designed in such a way that it prohibits
the vehicle from entering the wrong lane
in case the driver falls asleep or feel indisposed.
The motive behind this idea is to reduce the
number of road accidents, thus reducing the
cost of society and industry. Combined with
anti-collision radar in the car, it is expected that
the objective to reduce the number of accidents
will be met. The system is shown in Figure 3.
Another idea that has come up is to develop an
Internet along roads. The concept is illustrated in
Figure 4. Since the vehicles are becoming computer
platforms with communication capabilities,
the platform in each vehicle can be used as
a relay station for forwarding information from
one vehicle to the Internet. The Internet access
points can be located in lighting poles. The base
of the pole can contain the base station electronics:
the base station is not bigger than this. The
antenna elements fit easily in at the top of the
mast.
The technology required is the same as has been
used for a long time in military packet-radio systems.
Similar technologies are used for Bluetooth
and in experimental radio systems for
anarchistic communications.
Challenging problems are to analyse the routing
capabilities and the connectivity of such systems;
that is, what is the likelihood that a communications
path from one vehicle to an access
point of Internet exists at any time. We are then
faced with the mathematics of dynamic random
graphs; that is, graphs where the number of
nodes (i.e. cars and base stations), the location
of nodes and the connectivity between nodes
change with time. Apparently, very little is
known about such mathematical objects. One
problem is to estimate the density of base stations
so that the probability that a particular
vehicle cannot access the network is below a
given limit. Other questions are associated with
the overall connectivity in such graphs, for
example, what are the critical densities of nodes
(traffic density on the road) when connected
components, trees and cycles emerge in the
graph, when is the graph totally connected, and
how many such connections are likely to exist
on average between each node and the network.
Complex technological problems are associated
with the procedure and algorithms for handover
of calls from one car to another in this highly
dynamic system. If the diameter of a “cell” in
this system is 1 km and the car is driving at a
Telektronikk 1.2003