Analysing the Speed-flow Relationship in Urban Road Traffic

Juhász, Mattias; Koren, Cs; Mátrai, Tamás

doi:10.14513/actatechjaur.v9.n2.403

Cited by 5 publications

(2 citation statements)

References 6 publications

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“…In order to accomplish, first and foremost the validity of the speed-flow relationship for urban routes should be clarified. It was done in another part of this research and the results can be found in another paper (see Juhász et al, 2016). The applied method and relevant consequences are summarised in the following paragraphs.…”

Section: The Methodologymentioning

confidence: 99%

“…The empirical background of the function comes from the difference between observed and modelled traffic states illustrated by Figure 3. A function that describes the conversion between observed and modelled saturation for the congested states was defined based on the VDF estimations of Juhász et al (2016). It is presented by Equation 1:…”

Section: The Methodologymentioning

confidence: 99%

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Forecasting travel time reliability in urban road transpo

Juhász

Mátrai

Koren

2017

AoT

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Assessment of travel time reliability as a fundamental factor in travel behaviour has become a very important aspect in both transport modelling and economic appraisal. Improved reliability could provide a significant economic benefit if it is adequately calculated in cost-benefit analyses for which the theoretical background has already been set. However, methods to forecast travel time reliability as well as travel behaviour models including its effects are rather scarce and there is a need for development in this field. Another important aspect could be the influencing factor of reliability in travel demand management and related policy-making. Therefore, this paper intends to further analyse reliability focusing exclusively on urban road transport based on automatic measurements of journey times and traffic volumes from a dataset of the city of Budapest. The main finding and the novelty of the study is a model which can forecast the standard deviation of travel times based on the volume-capacity ratio and the free-flow travel time. The paper also provides a real-life numerical experiment in which the proposed model has been compared with other, existing ones. It proves that besides existing mean-delay-based models, travel time reliability can be forecasted based on the volume-capacity ratio with an adequate accuracy.

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Section: The Methodologymentioning

confidence: 99%

Section: The Methodologymentioning

confidence: 99%

Forecasting travel time reliability in urban road transpo

Juhász

Mátrai

Koren

2017

AoT

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Traffic and freight flow predictions and effects of capacity expansion in the urban–port road interface: The case of a port city in Poland

Bernacki

Lis

2022

Maritime Policy & Management

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Compatibility between delay functions and highway capacity manual on Iraqi highways

2022

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Volume delay functions (VDFs) are mathematical relationships used by the traffic allocation step of demand forecasting models to take into account the effect of increased traffic flow on the time spent to travel each possible route between different travel sources and destinations. The VDF is usually applied in static traffic assignment to describe the resultant link travel times, as a function of flow and capacity and free-flow travel time. This study aims to investigate the interface between the delay functions used by demand forecasting models and the highway capacity manual (HCM) model flow-speed relationships. The most commonly used VDFs in transport demand modeling packages in the literature were identified. The Bureau of Public Roads (BPR), conical functions (CF), Akçik and Troutbeck function (ATF), and delay logistics function (LF) were described. The four VDFs and the current HCM models were calibrated for the Iraqi road environment, and their compatibilities were examined. Results show that the best adjustments were obtained using the BPR function (quadratic error 0–0.012) and LF (quadratic error 0–0.002). The roles of CF and ATF were used with care, as both appear to neglect the delay in the condition of small to medium traffic patterns typical to country roads. Particularly, in response to single-lane roads, the LF has proven to be useful due to its potential to represent significant delays for low traffic flows and simultaneously produce more delays in congestion conditions; furthermore, the effect of flow as well as intersection spacing is obviously nonlinear. As flow reaches 600 pcu/h/lane, running time increases quickly. With more intersections per kilometer, the impact is obviously greater.

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Analysing the Speed-flow Relationship in Urban Road Traffic

Cited by 5 publications

References 6 publications

Forecasting travel time reliability in urban road transpo

Forecasting travel time reliability in urban road transpo

Traffic and freight flow predictions and effects of capacity expansion in the urban–port road interface: The case of a port city in Poland

Compatibility between delay functions and highway capacity manual on Iraqi highways

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