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involve external entities, for cities in Brazil, such as
the National Department of Traffic (Departamento
Nacional de Tr
ˆ
ansito - DENATRAN), which oversees
and rules traffic issues throughout the country, and the
National Land Transport Agency (Ag
ˆ
encia Nacional
de Transportes Terrestres - ANTT), responsible for
providing appropriate land transport to users.
The National Traffic Code (C
´
odigo Nacional
de Tr
ˆ
ansito - CNT) attributes the responsibility of
managing traffic to the municipality. Thus, the
problem vehicle congestion is the responsibility of
each municipality. That means the main community
involved with this issue is the Secretary of Traffic
and its possible branches (management board, de-
partments, sectors, and divisions).
It can be considered that the following com-
munities are involved in the System for Vehicle
Congestion Reduction: municipal secretary of traffic,
data analysts, moderators, traffic agents, watchper-
sons, drivers, passengers, and pedestrians. The roles
each one take up are described in the next section.
4.4 Roles, Contracts and Policies
The roles, contracts, and policies presented include
activities regarding the objects and communities
involved in the system. The system may be split
into three units: Controlling Unit, Pacifying Unit,
and Passive Unit. Those involved from the three
units may have characteristics in common such as
supplying information to the system.
The Controlling Unit is responsible for control-
ling the system and the information received by the
users. Those involved in this unit are:
Secretary of Traffic: Responsible for managing
and overseeing public passenger transport (e.g.,
buses, taxis), traffic signs, and the city’s fleet. The
sector must be able to generate data and historical
information such as the number and types of vehi-
cles, areas prone to having some sort of problem
(accidents, fallen trees, floods, gridlock, etc.), among
others, and store them in an open platform (SDI)
accessed by the system. It is the role of this secretary
to incentivize the use of the system, presenting the
benefits that may be reached. It is also the attribution
of the Secretary of Traffic to install and maintain
physical sensors to monitor the city;
Data Analyst: Responsible for developing analy-
ses of the data and identifying possible improvements
in the system. The analyses may combine different
sources of information such as from an SDI and VGI,
social media, or sensors, analyzing not only the data
produced by the specific application for the vehicle
congestion issue;
Moderator: Has the role of following, analyzing,
and filtering information provided mainly by the
citizens. Information not related to the system’s
purpose must be withheld so as not to harm the users.
The Pacifying Unit is responsible for monitoring
the system’s working environment, i.e., the traffic of
vehicles and pedestrians, the streets, etc. In addition,
the unit must contribute information to the system.
Those involved in this unit must be hired and be
identified in the system. They may be represented by:
Traffic Agent: Responsible for “developing
activities to improve the quality of life of the pop-
ulation, acting as a facilitator of sustainable urban
or road mobility, being guided, among others, by
constitutional principles of legality, impersonality,
morality, publicity, and efficiency” (DENATRAN,
2010). The agent must report in the system informa-
tion on any event that may cause congestion (e.g.,
accidents, floods);
Watchperson: Responsible for following and
monitoring using audio/video telecommunications
devices such as cameras and microphones. The
role also includes providing information of possible
events that may impact vehicle flow.
The Passive Unit is made up of the system
users that are not mandated to provide information.
However, it is essential that those users participate as
VGI contributors so that the system does not depend
only on information from physical sensors and the
pacifying unit. This unit may comprise:
Driver: Able to provide data such as speed and
geographic location through on-board systems or
satellite navigation installed in the vehicles. This
may be crucial to identify possible areas with con-
gestion by comparing the speed of vehicles with the
maximum speed allowed in that stretch of road over
a certain timeframe;
Passenger: Has the role of contributing informa-
tion on events that may impact the flow of vehicles
through VGI applications installed on or accessed by
mobile devices. Situations such as accidents, fallen
trees, floods, roadworks, and several others may be
reported in the system;
Pedestrian: Has the same role as the passenger,
however, not in a vehicle.
The specification of the EV of the System
for Vehicle Congestion Reduction is illustrated
in Figure 4. Each community is specified by
the stereotype EV CommunityContract ,
which contains a component stereotyped as
EV Community . Each of the components
has its dependence defined by the stereotype
EV Re finesAsCommunity , referring to the
classes stereotyped as EV CommunityOb ject
(Controlling Unit, Pacifying Unit, and Passive Unit).
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