Master's Dissertation
DOI
https://doi.org/10.11606/D.18.2018.tde-10092018-150848
Document
Author
Full name
Gabriel Jurado Martins de Oliveira
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 2018
Supervisor
Committee
Cunha, André Luiz Barbosa Nunes da (President)
Bessa Júnior, José Elievam
Isler, Cassiano Augusto
Title in Portuguese
Calibração da relação fluxo-velocidade para autoestradas e rodovias de pista dupla
Keywords in Portuguese
Calibração
HCM
Inferência bayesiana
Rodovias
Rodovias de pista dupla
Abstract in Portuguese
Title in English
Calibration of speed-flow relationship for freeways and multilane highways
Keywords in English
Bayesian inference
Calibration
Capacity
Freeways
HCM
Highways
Multilane highways
Speed-flow relationship
Abstract in English
The following research aims to outline a calibration method of the speed-flow relationship presented in the Highway Capacity Manual (HCM). The method is applied on freeways and multilane highways, leveraging the guidelines made by the authors that developed the manual. In order to support the calibration, a sample with more than 1.700.000 observations was used, collected by 34 traffic sensors on four highways at São Paulo state (SP-280, SP-348, SP270, and SP-021). Furthermore, the data treatment and cleaning process aimed to remove observations considered inappropriate from a model calibration perspective by filtering the original data through three main criteria: traffic flow only composed by passenger car, traffic under normal operations condition, and only containing observations which free flow regime applies. The third filtering criteria was applied by splitting free flow and congested regime through the threshold of density at capacity. To this extent, a capacity estimation method was proposed, aiming to analyse the average speed variation in function of the traffic flow. The assumption of the method relies in the concept that the traffic flow breakdown is a stochastic process, characterized by the abrupt drop in the average speed as function of the traffic flow increase. The moment that abrupt drop occurs is related to traffic breakdown and, consequently, to the capacity freeway capacity. Once the capacity was estimated, the speed at capacity was defined as the average of the speed associated with the flow at capacity while the density at capacity was estimated through the fundamental relationship of the traffic flow. The method was applied in 18 delimited highway traffic perimeter that reached their corresponding capacity and the results were considered satisfactory after comparing against values found in the literature. Furthermore, the speed-flow relationships calibration was performed for each of them individually. The results show that rural highways have in average higher free flow speed, capacity, calibration coefficient, speed at capacity and breakpoint than urban highways. Moreover, the breakpoint, which consists a constant free flow speed level, presented significant lower values in comparison to the literature.

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Publishing Date
2018-09-17

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