MEDEIROS, H. M.; http://lattes.cnpq.br/2626682063200243; MEDEIROS, Hamilton Martins de.
Resumo:
Roundabouts emerged as great solutions to solve traffic congestions in large urban centers. This
solution improves traffic safety and security once it increases the intersection capacity and
reduces waiting time. However, poorly designed intersections can interfere in these aspects.
This research aims to analyze the operational capability and efficiency of a roundabout located
in the city of Campina Grande. The study focuses mainly on the critical delay and service level
of the roundabout. In order to evaluate this intersection, we build an origin-destination matrix
based on the hour and day of the highest traffic flow. Data were collected using a tripod and a
cellphone recording, divided into four videos of 15 minutes each. For microsimulation, we used
the Vissim software and Wiedmann 74 and 99 models. From the results obtained through
microsimulation, we choose the most representative model by using the number of vehicles
counted at the same time-lapse as a calibration parameter. Adjusted parameters were selected
based on the literature. The critical gap was selected based on data collected from the road with
the most significant traffic volume in order to obtain the biggest number of accepted and
rejected gaps. Besides, the critical gap was calculated using the Raff and Wu deterministic
methods, while the simulation method was used to calculate other gap used in this study.
According to the results obtained with the origin-destination matrix, Monday is the weekday
that presents the highest traffic flow. Using the Wiedemann 74 model, the average error
regarding vehicles number was 14,4%, while using the Wiedmann 99 model, the average error
was only 11,8%. The deterministic methods did not show effectiveness and accuracy to
determine the critical gap. Whereas, the simulation method was effective because it calculated
a gap of 2.5 seconds, which means that drivers in Campina Grande are more aggressive in
intersections if compared to other cities. After evaluating the simulation results into three
different cases, we found that the roundabout operates at a service level B. Cases that provide
the greatest service level are the ones that prioritize the main road and semaphores installed in
it.