Traffic Theory

Three-Stream Model for Arterial Traffic

Bails, Constant
Hofleitner, Aude
Xuan, Yiguang
Bayen, Alexandre M.
2012

In this article, a new analytical traffic flow model is proposed for traffic dynamics at signalized intersections. During each cycle, both the arrival and the departure traffic are approximated by three distinct traffic streams with uniform density. Because of the similar representation of the arrival and the departure traffic, results from a single intersection can easily be extended to a series of intersections. With this model, the number of parameters of the model is tractable, leading to analytical solutions of the problem. It also is proved that the total delay of one-way...

Individual Speed Variance in Traffic Flow: Analysis of Bay Area Radar Measurements

Blandin, Sébastien
Salam, Amir
Bayen, Alexandre
2012

The recent increase of mobile devices able to measure individual vehicles speed and position with high accuracy brings new opportunities to traffic engineers. The large amount of individual probe measurements allows the study of phenomena previously unobservable with conventional sensing technologies, and the design of novel traffic monitoring and control strategies. However, challenges inherent to the use of speed and location data arise. One of the main difficulties of measurements collected from individual vehicles lie in their ability to provide relevant information on the...

Probability Distributions of Travel Times on Arterial Networks: Traffic Flow and Horizontal Queuing Theory Approach

Hofleitner, Aude
Herring, Ryan
Bayen, Alexandre
2012

In arterial networks, traffic flow dynamics are driven by the presence of traffic signals, for which precise signal timing is difficult to obtain in arbitrary networks or might change over time. A comprehensive model of arterial traffic flow dynamics is necessary to capture its specific features in order to provide accurate traffic estimation approaches. From hydrodynamic theory, arterial traffic dynamics are modeled under specific assumptions standard in transportation engineering. This flow model is used to develop a statistical model of arterial traffic. The statistical approach...

Trade-offs Between Inductive Loops and GPS Probe Vehicles for Travel Time Estimation: Mobile Century Case Study

Mazaré, Pierre-Emmanuel
Tossavainen, Olli‐Pekka
Bayen, Alexandre M.
Work, Daniel B.
2012

This article addresses the trade-offs between (i) velocity data collected from GPS smartphones in probe vehicles, and (ii), velocity data obtained from inductive loop detectors, for the purpose of computing travel times on a stretch of roadway. It is a case study which uses experimental data collected on one day in the San Francisco Bay Area, obtained as part of a 2008 field experiment known as Mobile Century. Estimates of the traffic velocity field are constructed using a velocity model equivalent to the Cell Transmission Model, and a traffic state estimation algorithm known as...

A Tractable Class of Algorithms for Reliable Routing in Stochastic Networks

Samaranayake, Samitha
Blandin, Sébastien
Bayen, A.
2012

The goal of this article is to provide the theoretical basis for enabling tractable solutions to the “arriving on time” problem and enabling its use in real-time mobile phone applications. Optimal routing in transportation networks with highly varying traffic conditions is a challenging problem due to the stochastic nature of travel-times on links of the network. The definition of optimality criteria and the design of solution methods must account for the random nature of the travel-time on each link. Most common routing algorithms consider the expected value of link travel-time as a...

Enhancing Privacy and Accuracy in Probe Vehicle-Based Traffic Monitoring via Virtual Trip Lines

Hoh, Baik
Iwuchukwu, Toch
Jacobson, Quinn
Work, Daniel
Bayen, Alexandre M.
Herring, Ryan
2012

Traffic monitoring using probe vehicles with GPS receivers promises significant improvements in cost, coverage, and accuracy over dedicated infrastructure systems. Current approaches, however, raise privacy concerns because they require participants to reveal their positions to an external traffic monitoring server. To address this challenge, we describe a system based on virtual trip lines and an associated cloaking technique, followed by another system design in which we relax the privacy requirements to maximize the accuracy of real-time traffic estimation. We introduce virtual trip...

Reconstruction of Boundary Conditions from Internal Conditions Using Viability Theory

Hofleitner, A.
Claudel, C.
Bayen, A.
2012

This article presents a method for reconstructing downstream boundary conditions to a HamiltonJacobi partial differential equation for which initial and upstream boundary conditions are prescribed as piecewise affine functions and an internal condition is prescribed as an affine function. Based on viability theory, we reconstruct the downstream boundary condition such that the solution of the Hamilton-Jacobi equation with the prescribed initial and upstream conditions and reconstructed downstream boundary condition satisfies the internal value condition. This work has important...

Automatic Inference of Map Attributes from Mobile Data

Hofleitner, Aude
Côme, E.
Oukhellou, L.
Lebacque, Jean-Patrick
Bayen, A.
2012

The development and update of reliable Geographic Information Systems (GIS) greatly benefits Intelligent Transportation Systems developments including real-time traffic management platforms and assisted driving technologies. The collection and processing of the data required for the development and update of GIS is a long and expensive process which is prone to errors and inaccuracies, making its automation promising. The article introduces a method which leverages the emergence of sparsely sampled probe vehicle data to update and improve existing GIS. We present an unsupervised...

On Sequential Data Assimilation for Scalar Macroscopic Traffic Flow Models

Blandin, Sébastien
Couque, Adrien
Bayen, Alexandre
Work, Daniel
2012

We consider the problem of sequential data assimilation for transportation networks using optimal filtering with a scalar macroscopic traffic flow model. Properties of the distribution of the uncertainty on the true state related to the specific nonlinearity and non-differentiability inherent to macroscopic traffic flow models are investigated, derived analytically and analyzed. We show that nonlinear dynamics, by creating discontinuities in the traffic state, affect the performances of classical filters and in particular that the distribution of the uncertainty on the traffic state at...

Providing In-Vehicle Soft Safety Alerts Using Mobile Millennium Data and Vehicle Event Information

Nowakowski, Christopher
Gupta, Somak Datta
Myers, Scott
Shladover, Steven
Bayen, Alexandre
2012

The Mobile Millennium project provided a platform for aggregating traffic information across various sources, including infrastructure sensors, commercial data feeds, probe vehicles, and probe cell phones. The Networked Traveler project provided the California PATH instrumented research vehicle platform used to both deliver vehicle probe data back to the infrastructure and to generate Advanced Driver Assistance Systems (ADAS) alerts to the drivers of those vehicles. The main theme of this collaboration project was to demonstrate the potential to create Enhanced Probe Vehicles (EPVs) by...