Capturing network properties with a functional form for the multi-modal macroscopic fundamental diagram

The effects of operational characteristics of the public transport system on the performance of the urban network traffic flow and the public transport system have been widely investigated at the local level. However, to the best of authors' knowledge there is no attempt to investigate these characteristics at the network level. This study bridges this gap through the notion of network macroscopic fundamental diagram (NMFD). In particular, the effects of the bus stop location (i.e. far-side and nearside) and berth number are discussed at the network level through simulating different scenarios in the central business district (CBD) of the city of Christchurch, New Zealand. In consistent with the local level studies, the outputs show that the far-side bus stops result in better network performance (i.e. larger capacity and critical density range) and a lower median for the network average delay of car traffic. The nearside bus stops instead lead to a lower median for the public transport system. The results reveal that increasing the berth number improves the network capacity and median of the network average delay for both modes. Finally, the impacts of the combination of the far-side and nearside bus stop on network performance have been discussed.

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“…Recently, Loder et al [31] presented the functional form of the 3D‐NMFD. The suggested function includes two parts.…”

Section: Macroscopic Modelling Of Urban Networkmentioning

confidence: 99%

Impacts of bus stop location and berth number on urban network traffic performance

Johari

Keyvan‐Ekbatani

Ngoduy

2020

IET intell. transp. syst

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“…Further, the parameter o describes the upper bound for the operational regime O. Loder et al (2019b) define planes which act as upper bounds for the pMFD in the (N c , N b , )-space. These planes include the N c , N b -plane.…”

Section: Normalizationmentioning

confidence: 99%

Simulation-Based Design of Urban Bi-modal Transport Systems

Tilg¹,

Abedin²,

Amini³

et al. 2020

Front. Future Transp.

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The three-dimensional passenger macroscopic fundamental diagram (pMFD) describes the relation of the network accumulation of public transport and private vehicles, and the passenger production. It allows for modeling the multi-modal traffic dynamics in urban networks and deriving innovative performance indicators. This paper integrates this concept into a multi-modal transport system design framework formulated as a simulation-based optimization problem. In doing so, we consider the competition for limited road space and the operational characteristics, such as congestion occurrences, at the strategic design level. We evaluate the proposed framework in a case study for the Sioux Falls network. Thereby, we deliver a proof of concept, and show that the proposed methodology indeed designs a transport system which benefits the overall system's performance. This paper further advances the integration of sequential model-based optimization techniques, macroscopic traffic flow concepts, and traffic simulation to design multi-modal transport systems. This supports transport planners and local authorities in composing efficient and robust transport networks.

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“…Most of the approaches proposed in the literature are based on the so-called uni-modal or 2D-MFD, which relates the accumulation of all vehicles to the mean flow of all vehicles in the network. Previous works (e.g., Boyac and Geroliminis, 2011;Chiabaut et al, 2014;Loder et al, 2017Loder et al, , 2019, suggest that the buses and cars affect the network dynamics in different ways. This phenomenon is clear in any urban network as public transport buses typically travel slower than cars and make frequent stops.…”

Section: Introductionmentioning

confidence: 99%

Empirical Validation of Bimodal MFD Models

Paipuri

Leclercq

2020

Front. Future Transp.

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This work attempts to validate the dynamic outputs of bi-modal MFD-based models, also referred to as 3D-MFD models, using empirical data. A previous study (Loder et al., 2017) gathered cars and public transport vehicles data in two different regions of Zurich city and showed that a well-defined 3D-MFD exists by proposing a functional form relating overall travel production to the accumulations of cars and public transport vehicles. This work aims to go one step further with the same data set to investigate if 3D-MFD embedded in dynamic conservation laws can predict the time evolution of the network traffic states. Two different approaches to estimate the inflow demand using outflow and mean speed evolutions are presented. The mean trip lengths are estimated using a network exploration technique. Accumulation-based, trip-based and accumulation-based with outflow delay models are considered in the validation study. It is concluded that a single bi-linear 3D-MFD fit is insufficient to predict traffic state evolution accurately. The current work proposes multi bi-linear 3D-MFD fits segregated depending on the time of the day. The proposed approach significantly improved the simulation results, where good correspondence with empirical data is obtained. Finally, it is shown that in multi-modal networks like Zurich, it is essential to consider the effect of public transport vehicles, when considering aggregated simulations. It is also shown that using a 2D-MFD by treating public transport vehicles and private cars alike, result in poor accordance with the field observations.

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Capturing network properties with a functional form for the multi-modal macroscopic fundamental diagram

Cited by 42 publications

References 31 publications

Impacts of bus stop location and berth number on urban network traffic performance

Impacts of bus stop location and berth number on urban network traffic performance

Simulation-Based Design of Urban Bi-modal Transport Systems

Empirical Validation of Bimodal MFD Models

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