Maria Alice Prudêncio Jacques

Portuguese two-lane highways: modelling crash frequencies for different temporal and spatial aggregation of crash data

Abstract.The identification of contributory factors to crash frequencies observed in different highway facilities can aid transportation and traffic management agencies to improve road traffic safety. In spite of the strategic importance of the national Portuguese road network, there are no recent studies concerned with either the identification of contributory factors to road crashes or Crash Prediction Models (CPMs) for this type of roadway. This study presents an initial contribution to this problem by focusing on the national roads NR-14, NR-101 and NR-206, which are located in Northern region of Portugal. They are two-lane single carriageway rural roads. This study analysed the crash frequencies, Average Annual Daily Traffic (AADT) and geometric characteristics of 88 two-lane road segments. The selected segments were 200-m-long and did not cross through urbanized areas. The fixed length of 200 meters corresponds to the road length used in Portugal to define a critical point. Data regarding the annual...

Safety performance models for urban intersections in Brazil

This paper presents a modeling effort for developing safety performance models (SPM) for urban intersections for three major Brazilian cities. The proposed methodology for calibrating SPM has been divided into the following steps: defining the safety study objective, choosing predictive variables and sample size, data acquisition, defining model expression and model parameters and model evaluation. Among the predictive variables explored in the calibration phase were exposure variables (AADT), number of lanes, number of approaches and central median status. SPMs were obtained for three cities: Fortaleza, Belo Horizonte and Brasília. The SPM developed for signalized intersections in Fortaleza and Belo Horizonte had the same structure and the most significant independent variables, which were AADT entering the intersection and number of lanes, and in addition, the coefficient of the best models were in the same range of values. For Brasília, because of the sample size, the signalized and unsignalized intersections were grouped, and the AADT was split in minor and major approaches, which were the most significant variables. This paper also evaluated SPM transferability to other jurisdiction. The SPM for signalized intersections from Fortaleza and Belo Horizonte have been recalibrated (in terms of the Cx) to the city of Porto Alegre. The models were adjusted following the Highway Safety Manual (HSM) calibration procedure and yielded Cx of 0.65 and 2.06 for Fortaleza and Belo Horizonte SPM respectively. This paper showed the experience and future challenges toward the initiatives on development of SPMs in Brazil, that can serve as a guide for other countries that are in the same stage in this subject.

Importance of Fuzzy Sets Definitions for Fuzzy Signal Controllers

The study conducted showed that the definitions of the fuzzy sets associated to the input variables of a given fuzzy signal controller must be taken very carefully as they affect both the actual controller response and the traffic performance.

Analysis of the evolution of trip generation rates associated to education institutions as published by ITE

This paper reviews and analyzes the land use documentation included in various editions of the Trip Generation manual published by the Institute of Transportation Engineers (ITE) concerning Land Use: 530 (High School) and Land Use: 550 (University) and spanning an assessment period of more than 20 years. Remarks and recommendations are made on the possibility of using the rates proposed in the 2012 edition of the manual to estimate the number of automobile trips generated by high schools and universities in Brazil. Overall the study showed that such rates lead to overestimates of trips as compared to those actually observed in Brazilian institutions. Furthermore, it was found that the rates and models adopted in each successive edition of the ITE manual are obtained by aggregating the more recent studies to the database of the preceding edition without discarding the older studies so that more recent efforts to alter the modal distribution for trips generated by such sites are not fully captured in the newest editions.

Modelo para estimativa do fluxo de saturação desenvolvido a partir das condições do tráfego de Brasília

Dadas as dificuldades de obtencao do valor do fluxo de saturacao in loco para diversas situacoes, ele e frequentemente estimado a partir de modelos. Assim, esses modelos precisam refletir, da melhor forma possivel, as condicoes locais de operacao do trafego. Este trabalho apresenta o desenvolvimento de um modelo matematico para estimativa do fluxo de saturacao, por faixa de trânsito, para as condicoes do trafego da cidade de Brasilia. A tecnica de modelagem utilizada foi a analise de regressao, e os dados para o desenvolvimento do modelo foram coletados em 20 intersecoes, perfazendo um total de 50 faixas de trânsito observadas. Os resultados das analises estatisticas efetuadas revelaram que o modelo e adequado para estimar o fluxo de saturacao por faixa de trânsito para a cidade de Brasilia. A sua utilizacao em outras cidades brasileiras e possivel, desde que seja devidamente calibrado.