if you had a device that allowed you to communicate with the driver of
the car that's tailgating you? Raphael Lamas finds out if drivers would
use such a device, and if so, how they would use it.
is a social task where drivers frequently need to communicate with
other road users to make their intentions clear and avoid accidents.
Driver interaction, which is mostly nonverbal in nature, has specific
characteristics that can make it difficult to determine the precise
intent of each driver involved. In the first place, the vehicle creates a
spatial separation and a physical barrier between drivers. Also, the
interaction usually needs to be completed in a short space of time
because of the high speed of the vehicles. Finally, visual information
such as facial expressions or gestures may not be easily visible,
especially when driving at night.
Driver interaction could be
enhanced by an electronic driver-to-driver communication device, which
would allow users to exchange messages with each other. Ideally, the
device would be available in all vehicles and should be designed in such
a way that it does not negatively affect the main driving task.
exploratory study was designed to investigate the effectiveness of the
use of a hypothetical device on the outcome of different driving
scenarios. Studies have shown variations in different countries in
relation to several aspects of driver behaviour. Therefore, this study
also aimed to investigate how drivers from two different countries,
Brazil and the UK, would interact with others in the same scenarios
either in formal or informal ways.
are extremely helpful to explore issues with any technology before it
is implemented. Six different driving scenarios were used in this study
to present information and evoke opinions from participants. These
scenarios cover a wide range of different forms of communication:
- The main driver is unable to overtake a very slow driver in front.
- An angry driver tailgates the main driver who is driving calmly on a single carriageway.
- Interaction between the main driver and the other driver in a friendly exchange.
- While overtaking, the main driver notices that the other driver’s vehicle has a flat tyre.
- The other driver needs to give way to the main driver who is leaving a building.
- The main driver gets stuck in the middle of a junction, blocking vehicles coming from the other direction.
total of 24 participants, 12 from each country, participated in the
study. They were recruited on the basis that they had to regularly drive
at least three times a week and must have held a valid driving licence
from either the UK or Brazil for at least five years.
were asked questions regarding each scenario they had just read. All
participants answered questions based on the same set of six scenarios,
which were randomised. After all the questions regarding a scenario had
been answered, participants were then presented with the next scenario
and the same process started again.
Some of the questions
presented to the participants were related to a communication device. It
was not explained to the participants what this device would be like,
leaving it open to their imagination without any further information.
Participants were only asked to think of an electronic device available
in the vehicle, which would allow them to exchange messages with other
drivers. At the end, participants were asked their opinions on what they
thought would be the interface of the device and the best way to
interact with it. The study highlighted important results, which will
then be helpful in designing the next studies.
cultural differences between Brazilian and British drivers were found
using the traditional means of communication, such as honking their
horn, flashing headlights and making gestures, no significant
differences were found when using the device as a means of
communication. Both British and Brazilian drivers would use the
hypothetical communication device in the same way and with similar
message content. Issues with the device, such as the potential for
abusive use were found equally in both cultures.
reported they would use the device to send messages in all the
scenarios but they would avoid replying to the other driver if an
aggressive message was sent. Most of them would not like to antagonise
an angry driver and get involved in a road rage scenario. Participants
would not like to become distracted from the main driving task by
engaging in a prolonged conversation with the other driver through the
device, even if it was hands-free.
Several studies mention the
effect of the presence of passengers on the driver. This study found
that this could also equally apply when using an electronic device to
exchange messages. Drivers can feel inhibited to use the device when
they have a passenger with them, especially if this passenger is a child
or an older person who might not react well to an aggressive or
on the results of the study, it was possible to draw some initial
design recommendations for a driver-to-driver communication device.
Firstly, it is critical to design a suitable human-machine interface
that takes into consideration the distraction of drivers. Therefore, a
voice-based interface has many advantages even though it may not be
appropriate for prolonged interaction.
Secondly, most participants
reported that they would prefer to exchange audio messages rather than
text messages. Audio messages could be transmitted either with the
actual voice of the driver or with a computer-generated voice. Most
participants preferred a synthesised voice, especially because of their
concern with how the other driver would interpret the tone of their
voice. The message with the actual voice of the driver would carry their
emotions and could be aggressive in tone. Emotions could change the
outcome of the interaction. An aggressive reply from the other driver
could make the main driver angrier.
Thirdly, drivers could only
have access to a set of pre-defined messages or be allowed to express
themselves freely. Although free-content messages could cover any
communication scenario, they could also lead to inappropriate use. The
set of pre-defined messages should be carefully considered, as a
restricted number of options might limit the use of the device with a
lower acceptance by the general population. On the other hand, an
increased number of options could take a longer time for drivers to
decide and choose which one to use.
Fourthly, it was found that it
is important that the interface of the device should identify the
driver who sent the message in some way. Identification could be made,
for example, by giving the make of the vehicle, model and registration
plate, which may not be seen by all drivers. Another option might be to
display the driver’s name or picture in a visual display. Both options
could violate the driver’s privacy but at the same time an anonymous
message might lead to abusive use.
Finally, drivers could share
with other drivers their current state. For example, this could be
anything related to their current emotional feelings or a reason for
driving slowly. The interface of the device would then display the
information to all drivers. This information would help drivers
understand why the person is driving in a particular way, making their
intentions clearer and improving their interaction.
results of the study also found some issues related to the device. The
first issue is related to the abusive use of the device. Drivers could
use the device for other purposes or in frivolous talk, which could lead
to drivers being distracted by an overload of unnecessary messages.
Some rules of etiquette should therefore be defined before this device
is available to the general public.
The device may also not be
appropriate to use in all scenarios due to the duration of interaction.
In some cases, the traditional means of communication could be quicker
than using the device to send a message. This is especially true if both
vehicles are travelling at speed on a motorway, or if the situation in
which the driver needs to interact with others can be resolved quickly,
for example a driver blocking others for a very short period of time
By Raphael Lamas, PhD student at the Human Factors Research Group at the University of Nottingham
This article first appeared in issue 532 of The Ergonomist, October 2014.