224 Just ordinAry robots
trac accidents. Several studies show that in more than 90% of cases,
accidents occur due to human error and that only 5%–10% are the
result of deciencies in the vehicle or the driving environment (see,
e.g., Broggi, Zelinsky, Parent, & orpe, 2008; Dewar & Olson,
2007; National Highway Trac Safety Administration, 2008).
Autonomous vehicles have continuous complete attention and focus,
keep within the speed limit, do not get drunk, abstain from aggres-
sive behavior, and so on. In addition, Peter Sweatman, director of the
University of Michigan Transportation Research Institute, states that
“[h]umans are not suited to monitoring tasks like driving [because]
human attention is easily diverted.”* In fact, the researchers at the
institute state that the solution to preventing trac accidents is not
more speed limits, airbags or distracted driving policies, and so on,
but getting humans out of the loop. But before the human factor can
be switched o in trac, the autonomous vehicle must be thoroughly
tested in the actual dynamic trac before safely functioning on the
road. Levy and Murmane state that “[a]s the driver makes his left turn
against trac, he confronts a wall of images and sounds generated by
oncoming cars, trac lights, storefronts, billboards, trees, and a traf-
c policeman. Using his knowledge, he must estimate the size and
position of each of these objects and the likelihood that they pose a
hazard. … Articulating this knowledge and embedding it in software
for all but highly structured situations are at present enormously dif-
cult tasks” (Levy & Murmane, 2004, p. 28). Or, if an autonomous
car is programmed to faithfully follow the trac regulations, then it
might refuse to drive in automatic mode if, for example, a headlight is
broken, or it might come to a complete stop when a small tree branch
pokes out onto a highway because crossing a continuous line is pro-
hibited whereas humans would simply drift a little into the opposite
lane and drive around it (see also Lin, 2013).
According to Smith (2012), autonomous cars cannot yet be claimed
to be signicantly safer than those with human drivers. In his analy-
sis, which uses a Poisson distribution and assumes the accuracy of the
crash and mileage estimates, he concludes that for autonomous cars
to be declared safer, they would need to drive 1.17 million kilometers
*
http://www.engin.umich.edu/college/about/news/stories/2013/november/
driverless-connected-cars.