Evaluating Impacts of Traffic Incidents on CO 2 Emissions in Express Roads
41
for the two cases. So, to estimate the CO 2 emissions without incidents, we used
Eq. (2). The same traffic flow of the scenario with incidents was considered, but the
capacity and speed reduction imposed by the incidents were not.
In summary, Eq. (2) is used for scenarios with incidents that do not generate
additional congestion queues and for the scenario without incidents, only the speed
values change in these two cases. Finally, Eq. (4) is used in scenarios with incidents
that generate congestion queues.
4 Case Study
Traffic congestion aggravates air pollutant emissions in urban areas [22]. In addition
to recurrent congestion in cities which occur due to lack of capacity in the system,
there are nonrecurring congestions due to incidents that aggravate the situation of
urban mobility [37, 42].
In the Rio de Janeiro city, this reality is not different. The city suffers of daily traffic
congestion that is intensified by the incidents, which have serious social, economic
and environmental impacts. So, in order to reduce these problems, CET-Rio performs
road operations for service the incidents using tows trucks, motorcycles and pickups.
Considering the tows trucks, CET-Rio has three types: (i) light tow truck for passenger
cars; (ii) heavy tow truck for trucks and buses; and (iii) super heavy tows trucks for
big trucks.
In order to verify the impacts of the incidents, real data were obtained in the
Rio de Janeiro city. One of the main express roads is Avenida Brasil, which is the
largest road in the city with 58 km and with an expressive number of calls to attend
incidents. It is the main road connecting the city center, the suburb and the west zone
as well as the main access to the port and the route for the three main highways
that give access the city (Ponte Rio-Niterói, a bridge, Rodovia Washington Luiz and
Rodovia Presidente Dutra, highways). The average daily flow of Avenida Brasil is
210 thousand vehicles, generating 770 calls for incidents on average per month.
The database used consists of 3,080 records that present the incident type, its
location (georeferenced data), the time required and the vehicle involved. In addition,
during the data treatment, it was identified that 282 records were incomplete. Thus,
2,798 records were used. Among them, 61.1% are broken-down vehicles, 16.7%
are accidents and 9.2% are flat tires, see Fig. 3 (others represent incidents with a
low frequency of events such as fires and being run over). In addition, 39.5% of the
occurrences were serviced by motorcycles and 25.4% by light tows trucks, see Fig. 4.
4.1 Emissions and Exploratory Analysis
To reach the objectives of this study, it is necessary to calculate emissions for the real
scenario, with the occurrence of incidents, and the emissions for a scenario without
41
for the two cases. So, to estimate the CO 2 emissions without incidents, we used
Eq. (2). The same traffic flow of the scenario with incidents was considered, but the
capacity and speed reduction imposed by the incidents were not.
In summary, Eq. (2) is used for scenarios with incidents that do not generate
additional congestion queues and for the scenario without incidents, only the speed
values change in these two cases. Finally, Eq. (4) is used in scenarios with incidents
that generate congestion queues.
4 Case Study
Traffic congestion aggravates air pollutant emissions in urban areas [22]. In addition
to recurrent congestion in cities which occur due to lack of capacity in the system,
there are nonrecurring congestions due to incidents that aggravate the situation of
urban mobility [37, 42].
In the Rio de Janeiro city, this reality is not different. The city suffers of daily traffic
congestion that is intensified by the incidents, which have serious social, economic
and environmental impacts. So, in order to reduce these problems, CET-Rio performs
road operations for service the incidents using tows trucks, motorcycles and pickups.
Considering the tows trucks, CET-Rio has three types: (i) light tow truck for passenger
cars; (ii) heavy tow truck for trucks and buses; and (iii) super heavy tows trucks for
big trucks.
In order to verify the impacts of the incidents, real data were obtained in the
Rio de Janeiro city. One of the main express roads is Avenida Brasil, which is the
largest road in the city with 58 km and with an expressive number of calls to attend
incidents. It is the main road connecting the city center, the suburb and the west zone
as well as the main access to the port and the route for the three main highways
that give access the city (Ponte Rio-Niterói, a bridge, Rodovia Washington Luiz and
Rodovia Presidente Dutra, highways). The average daily flow of Avenida Brasil is
210 thousand vehicles, generating 770 calls for incidents on average per month.
The database used consists of 3,080 records that present the incident type, its
location (georeferenced data), the time required and the vehicle involved. In addition,
during the data treatment, it was identified that 282 records were incomplete. Thus,
2,798 records were used. Among them, 61.1% are broken-down vehicles, 16.7%
are accidents and 9.2% are flat tires, see Fig. 3 (others represent incidents with a
low frequency of events such as fires and being run over). In addition, 39.5% of the
occurrences were serviced by motorcycles and 25.4% by light tows trucks, see Fig. 4.
4.1 Emissions and Exploratory Analysis
To reach the objectives of this study, it is necessary to calculate emissions for the real
scenario, with the occurrence of incidents, and the emissions for a scenario without