Traffic Operations and Management

Link Density Inference from Cellular Infrastructure

Yadlowsky, Steve
Thai, Jérôme
Wu, Cathy
Pozdnukov, Alexey
Alexandre Bayen
2015

This work explores the problem of estimating road link densities from cellular tower signals by mobile subscribers in urban areas. The authors pose the estimation problem as a quadratic program, and present a robust framework that produces vehicle density estimates and is suitable for large-scale problems. The authors demonstrate that both simple and sophisticated models of cellular network connections can be handled robustly by the framework, without sacrificing efficiency or scalability. The authors present a numerical experiment on the I-15 corridor in San Diego based on a...

Evaluation of Horizontal and Vertical Queueing Models in Relation to Observed Trajectory Data in a Signalized Urban Traffic Network

Anderson, Leah
Gomes, Gabriel
Alexandre Bayen
2015

While the Cell Transmission Model (CTM) is generally accepted as a standard representation of traffic flows on freeways with long links and uninterrupted flows, less is known about the accuracy of CTM or other macroscopic queueing models on urban road networks with short links and frequent flow blockages due to signal control. In fact, almost all existing validations of CTM focus on modeling freeways. In this paper, the authors aim to provide evidence towards selecting the appropriate queueing model dynamics for use in analysis and control of a large-scale network of signalized...

Anatomy of a Crash

Marzuoli, Aude
Boidot, Emmanuel
Feron, Eric
Erp, Paul B. C. van
Ucko, Alexis
Alexandre Bayen
2014

Transportation networks constitute a critical infrastructure enabling the transfers of passengers and goods, with a significant impact on the economy at different scales. Transportation modes, whether air, road or rail, are coupled and interdependent. The frequent occurrence of perturbations on one or several modes disrupts passengers' entire journeys, directly and through ripple effects. The present paper provides a case report of the Asiana Crash in San Francisco International Airport on July 6th 2013 and its repercussions on the multimodal transportation network. It studies the...

Multimodality in a Metroplex Environment: A Case Study in the San Francisco Bay Area

Marzuoli, Aude
Feron, Eric
Hansen, Mark
Alexandre Bayen
Boidot, Emmanuel
2015

The present paper focuses on the crisis management following Asiana Crash at San Francisco International Aiport in July 2013.

Approximate Bilevel Programming via Pareto Optimization for Imputation and Control of Optimization and Equilibrium Models

Thai, Jérôme
Hariss, Rim
Alexandre Bayen
2015

We consider the problem of imputing the function that describes an optimization or equilibrium process from noisy partial observations of nearly optimal (possibly non-cooperative) decisions. We generalize existing inverse optimization and variational inequality problems to construct a novel class of multi-objective optimization problems: approximate bilevel programs. In this class, the “ill” nature of the complementary condition prevalent in bilevel programming is avoided, and residual functions commonly used for the design and analysis of iterative procedures, are a powerful tool to study...

Variational Lagrangian Data Assimilation in Open Channel Networks

Wu, Qingfang
Tinka, Andrew
Weekly, Kevin
Beard, Jonathan
Alexandre Bayen
2015

This article presents a data assimilation method in a tidal system, where data from both Lagrangian drifters and Eulerian flow sensors were fused to estimate water velocity. The system is modeled by first-order, hyperbolic partial differential equations subject to periodic forcing. The estimation problem can then be formulated as the minimization of the difference between the observed variables and model outputs, and eventually provide the velocity and water stage of the hydrodynamic system. The governing equations are linearized and discretized using an implicit discretization scheme,...

Adjoint-Based Optimization on a Network of Discretized Scalar Conservation Laws with Applications to Coordinated Ramp Metering

Reilly, Jack
Samaranayake, Samitha
Delle Monache, Maria
Krichene, Walid
Goatin, Paola
Alexandre Bayen
2015

The adjoint method provides a computationally efficient means of calculating the gradient for applications in constrained optimization. In this article, we consider a network of scalar conservation laws with general topology, whose behavior is modified by a set of control parameters in order to minimize a given objective function. After discretizing the corresponding partial differential equation models via the Godunov scheme, we detail the computation of the gradient of the discretized system with respect to the control parameters and show that the complexity of its computation scales...

Travel Time and Point Speed Fusion Based on a Macroscopic Traffic Model and Non-linear Filtering

Gundlegård, David
Allström, Andreas
Bergfeldt, Erik
Alexandre Bayen
Ringdahl, Rasmus
2015

The number and heterogeneity of traffic sensors are steadily increasing. A large part of the emerging sensors are measuring point speeds or travel times and in order to make efficient use of this data, it is important to develop methods and frameworks for fusion of point speed and travel time measurements in real-time. The proposed method combines a macroscopic traffic model and a non-linear filter with a new measurement model for fusion of travel time observations in a system that uses the velocity of cells in the network as state vector. The method aims to improve the fusion efficiency,...

Hybrid Approach for Short-Term Traffic State and Travel Time Prediction on Highways

Allström, Andreas
Ekström, Joakim
Gundlegård, David
Ringdahl, Rasmus
Rydergren, Clas
Alexandre Bayen
Patire, Anthony D.
2016

Traffic management and traffic information are essential in urban areas and require reliable knowledge about the current and future traffic state. Parametric and nonparametric traffic state prediction techniques have previously been developed with different advantages and shortcomings. While nonparametric prediction has shown good results for predicting the traffic state during recurrent traffic conditions, parametric traffic state prediction can be used during nonrecurring traffic conditions, such as incidents and events. Hybrid approaches have previously been proposed; these approaches...

Multimodal Impact Analysis of an Airside Catastrophic Event: A Case Study of the Asiana Crash

Marzuoli, Aude
Boidot, Emmanuel
Feron, Eric
van Erp, Paul B. C.
Ucko, Alexis
Alexandre Bayen
Hansen, Mark
2016

Transportation networks constitute a critical infrastructure enabling the transfers of passengers and goods, with a significant impact on the economy at different scales. Transportation modes, whether air, road, or rail, are intrinsically coupled through passenger transfers and are interdependent. The frequent occurrence of perturbations on one or several modes disrupts passengers' entire journeys, directly and through ripple effects. This paper provides a case report of the Asiana crash in San Francisco International Airport (SFO) on July 6, 2013, and its repercussions on the multimodal...