Evaluating Impacts of Traffic Incidents on CO 2 Emissions in Express Roads
37
reference and easy to obtain; (iii) it has a wide coverage of possible combinations of
technologies and fuels; and (iv) it considers many factors such as fuel types, engines
and vehicle types.
In order to achieve the objectives of this study, the remainder of this chapter is
organized as follows. Section 2 presents the methodology used. Section 3 describes
the MEET model needed to estimate CO 2 emissions considering two cases: with
and without incidents. Section 4 describes the case study, presents and discusses
the results and indicates the possible actions necessary to minimize the problems
encountered. Finally, Sect. 5 presents the final considerations of this study.
2 Methodology
Traffic incidents contribute to the increase in CO 2 emissions due to the congestion
generated, however efficient and quick responses to the incidents lead to the reduction
of this externality [13]. In addition, environmental, social and political pressures to
reduce the impacts associated with CO 2 emissions are increasing rapidly [18]. Thus,
it becomes necessary to develop strategies to minimize these problems [22].
Therefore, the methodology proposed in this study is divided into six stages, as
shown in Fig. 1, which seeks to: (i) estimate the increase in CO 2 emissions, due
to the occurrence of incidents; (ii) analyze which incident type most aggravates the
situation; and (iii) propose actions in order to mitigate the problem.
In Stage 1, a bibliographic review is performed in order to identify studies about
the impact of emissions on the urban environment, as well as ways to estimate
emissions and the intrinsic relationship between CO 2 emissions and traffic speed.
In Stage 2, the mathematical model needed to calculate CO 2 emissions on an urban
road is determined, based on the speed reduction caused by the incidents.
In Stage 3, data are collected such as the history of traffic incidents, the location
of the occurrences, the flow parameters (vehicle speed and flow) and the traffic
composition, i.e., the percentage of cars, buses and trucks. In Stage 4, CO 2 emissions
are estimated considering the occurrences of incidents by applying the MEET model.
It is worth mentioning that the duration of the incident is considered from the moment
that the vehicle impedes the regular traffic flow until the moment when it is removed.
This stage also estimates the CO 2 emissions without incidents (considering only the
regular traffic flow). To compare the CO 2 emissions with and without the incident,
we considered the same duration time (the duration of the incident).
In Stage 5, an exploratory analysis of the results is performed. The analysis is
performed globally, seeking to evaluate the impact on CO 2 emissions due to the
occurrence of incidents, and then it is carried out in a grouped manner, seeking to
understand the incident type, time and vehicle that most generates emissions. In
Stage 6, there is a discussion and proposal for actions that can be taken to reduce
CO 2 emissions, based on the analysis of the previous Stages 1 and 5.
37
reference and easy to obtain; (iii) it has a wide coverage of possible combinations of
technologies and fuels; and (iv) it considers many factors such as fuel types, engines
and vehicle types.
In order to achieve the objectives of this study, the remainder of this chapter is
organized as follows. Section 2 presents the methodology used. Section 3 describes
the MEET model needed to estimate CO 2 emissions considering two cases: with
and without incidents. Section 4 describes the case study, presents and discusses
the results and indicates the possible actions necessary to minimize the problems
encountered. Finally, Sect. 5 presents the final considerations of this study.
2 Methodology
Traffic incidents contribute to the increase in CO 2 emissions due to the congestion
generated, however efficient and quick responses to the incidents lead to the reduction
of this externality [13]. In addition, environmental, social and political pressures to
reduce the impacts associated with CO 2 emissions are increasing rapidly [18]. Thus,
it becomes necessary to develop strategies to minimize these problems [22].
Therefore, the methodology proposed in this study is divided into six stages, as
shown in Fig. 1, which seeks to: (i) estimate the increase in CO 2 emissions, due
to the occurrence of incidents; (ii) analyze which incident type most aggravates the
situation; and (iii) propose actions in order to mitigate the problem.
In Stage 1, a bibliographic review is performed in order to identify studies about
the impact of emissions on the urban environment, as well as ways to estimate
emissions and the intrinsic relationship between CO 2 emissions and traffic speed.
In Stage 2, the mathematical model needed to calculate CO 2 emissions on an urban
road is determined, based on the speed reduction caused by the incidents.
In Stage 3, data are collected such as the history of traffic incidents, the location
of the occurrences, the flow parameters (vehicle speed and flow) and the traffic
composition, i.e., the percentage of cars, buses and trucks. In Stage 4, CO 2 emissions
are estimated considering the occurrences of incidents by applying the MEET model.
It is worth mentioning that the duration of the incident is considered from the moment
that the vehicle impedes the regular traffic flow until the moment when it is removed.
This stage also estimates the CO 2 emissions without incidents (considering only the
regular traffic flow). To compare the CO 2 emissions with and without the incident,
we considered the same duration time (the duration of the incident).
In Stage 5, an exploratory analysis of the results is performed. The analysis is
performed globally, seeking to evaluate the impact on CO 2 emissions due to the
occurrence of incidents, and then it is carried out in a grouped manner, seeking to
understand the incident type, time and vehicle that most generates emissions. In
Stage 6, there is a discussion and proposal for actions that can be taken to reduce
CO 2 emissions, based on the analysis of the previous Stages 1 and 5.