role for interaction designers in understanding and
reshaping social attitudes between drivers, riders,
and pedestrians in a manner that motivates safe
and courteous behaviors.
A detailed example follows.
advised for upright bikes, but on an HPV that’s low
to the ground, you have the added problem that
even if all of the stopped cars have noticed you,
the cars approaching the intersection from the
other direction cannot see you at all. If a car at the
intersection travelling in the opposite direction is
waiting for the car ahead of you to pass through
the intersection before turning left, it is unlikely to
notice or wait for you to go through the intersection before it does so.
There are no good options, and that is a problem.
The interaction design problem that emerges
is one of figuring out how to make the various
commuters aware of one another’s locations and
intentions in an infrastructure shared by vehicles
of various sizes and degrees of insulation from
the environment. With a fresh infrastructure,
the problem is easier—simply have three lanes
and three types of traffic signals, one each for
regular vehicles, one for HPVs, and one for pedestrians. Such infrastructure exists in some cities—
Eindhoven in the Netherlands is a good example.
More commonly, where such infrastructure does
not exist and in the presence of our three or more
classes of travelers, there needs to be a system
of signaling that works in the shared space. Such
a system might incorporate mechanisms of augmentation for hand gestures and eye contact, LED
lights, RFID tags and sensors, sensors that connect
to in-vehicle displays, and other mechanisms of
awareness. The design of such systems—my mellow velo friends—is an opportunity for interaction
designers to help save the day, and perhaps the
Safety and Signals
Let’s take a look at one of these issues and opportunities in a little detail. Suppose you’re riding your
velomobile to work and you arrive at an intersection with a red traffic light. Furthermore, suppose
that four cars are lined up at the intersection.
Also, assume that there is oncoming traffic, which
may turn left when the light turns green. Finally,
assume that you are in a country where cars drive
on the right side of the road. Do you:
A. Go onto the sidewalk to pass the
B. Pass the cars to the right staying on
C. Pass the cars on the left?
D. Stop behind the last of the stopped cars,
close to the curb?
E. Stop behind the last of the stopped cars,
centered behind the last one?
If you choose A, the problem is that you become
a menace to pedestrians, and furthermore, you
run the risk of being hit by a car turning right at
the intersection since drivers aren’t used to paying
attention to things that move fast on sidewalks.
If you choose option B, you run the risk of being
hit by a car that attempts to park, or turn right, or
is too close to the curb. On an upright bicycle, the
car may see you in its passenger-side mirror. On
a recumbent, there is much less chance of a car
noticing your approach from behind, especially on
a tadpole trike or velomobile.
If you choose option C, I’m really worried about
If you choose option D, you run the lesser but
almost certainly lethal risk of being squashed
if the last of the cars decides to back up for any
reason. If you are on a tadpole trike or velomobile, there is little chance that the last of the cars
knows you are there.
If you choose option E, you increase the possibility that the last car will notice you only by a little,
but you make it easier for a car approaching from
behind to notice you and respect your position
in the line of stopped vehicles. Option E is often
ABOUT THE AUTHOR Eli Blevis serves on the
faculty in the Human-Computer Interaction Design
program of the School of Informatics at Indiana
University, Bloomington. Dr. Blevis’s primary area
of research, and the one for which he is best
known, is sustainable interaction design. This area
of research and Dr. Blevis’s core expertise are situated within the
confluence of human computer interaction as it relates to the com-
puting and cognitive sciences, and design as it relates to the reflec-
tion of design criticism and the practice of critical design. Dr. Blevis
has published more than 40 articles and papers and has given sev-
eral invited colloquia internationally on sustainable interaction
design and the larger context of notions of design.
January + February 2009
© 2009 ACM 1072-5220/09/0100 $5.00