Traffic Operations and Management

Virtual Trip Lines for Distributed Privacy-Preserving Traffic Monitoring

Hoh, Baik
Gruteser, Marco
Herring, Ryan
Ban, Jeff
Work, Daniel
Bayen, Alexander M.
2008

Automotive traffic monitoring using probe vehicles with Global Positioning System receivers promises significant improvements in cost, coverage, and accuracy. 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 propose a system based on virtual trip lines and an associated cloaking technique. Virtual trip lines are geographic markers that indicate where vehicles should provide location updates. These markers can be placed to avoid particularly privacy...

Convex Formulations of Aggregate Network Air Traffic Flow Optimization Problems

Work, Daniel B.
Bayen, Alexandre M.
2008

The problem of regulating air traffic in the en route airspace of the national airspace system is studied using an Eulerian network model to describe air traffic flow. The evolution of traffic on each edge of the network is modeled by a modified Lighthill-Whitham-Richards partial differential equation. We pose the problem of optimal traffic flow regulation as a continuous optimization program in which the partial differential equation appears in the constraints. The equation is transformed with a variable change which removes t nonlinearity in the control variables and enables us to use...

Convex Formulations of Air Traffic Flow Optimization Problems

Work, Daniel B.
Bayen, Alexandre M.
2008

The problem of regulating air traffic in the en route airspace of the National Airspace System is studied using a Eulerian network model to describe air traffic flow. The evolution of traffic on each edge of the network is modeled by a modified Lighthill-Whitham-Richards partial differential equation. The equation is transformed with a variable change, which makes it linear and enables us to use linear finite difference schemes to discretize the problem. We pose the problem of optimal traffic flow regulation as a continuous optimization program in which the partial differential equation...

An Ensemble Kalman Filtering Approach to Highway Traffic Estimation Using GPS Enabled Mobile Devices

Work, Daniel B.
Tossavainen, Olli‐Pekka
Blandin, Sébastien
Bayen, Alexandre M.
Iwuchukwu, Tochukwu
Tracton, Kenneth
2008

Traffic state estimation is a challenging problem for the transportation community due to the limited deployment of sensing infrastructure. However, recent trends in the mobile phone industry suggest that GPS equipped devices will become standard in the next few years. Leveraging these GPS equipped devices as traffic sensors will fundamentally change the type and the quality of traffic data collected on large scales in the near future. New traffic models and data assimilation algorithms must be developed to efficiently transform this data into usable traffic information. In this work, we...

Optimal Sensor Requirements

Ban, Xuegang (Jeff)
Bayen, Alexandre M.
Chu, Lianyu
Danczyk, Adam
Herrera, Juan‐Carlos
2009

PATH Task ORder 6328 addresses the optimal deployment of traffic detectors on freeway to ensure that adequate information is collected at the lowest possible cost. The project team produced a study framework and tools that can be applied locally to test the sensitivity of traffic data quality to detectors location and spacing, and ultimately recommend a deployment plan.Various types of traffic detectors, including loop detectors, radars, toll tag readers and video cameras are deployed on highways. They provide the data needed to run traffic management applications such as ramp metering...

Optimal Sensor Placement for Freeway Travel Time Estimation

Ban, Xuegang (Jeff)
Bayen, Alexandre M.
Herring, Ryan
2009

This article presents a modeling framework and a polynomial solution algorithm for determining optimal locations of point detectors used to compute freeway travel times. First, an objective function is introduced to minimize the deviation of estimated and actual travel times of all individual sub-segments of a freeway route. By discretizing the problem in both time and space, we formulate it as a dynamic programming model, which can be solved via a shortest path search in an acyclic graph. Numerical examples are provided to illustrate the model and algorithm using microscopic traffic...

Using Mobile Phones to Forecast Arterial Traffic through Statistical Learning

Herring, Ryan
Hofleitner, Aude
Amin, Saurabh
Abou Nasr, Tania
Khalek, Amin Abdel
Abbeel, Pieter
Bayen, Alexandre M.
2010

This article introduces the new component of Mobile Millennium dedicated to arterial traffic. Mobile Millennium is a pilot system for collecting, processing and broadcasting real-time traffic conditions through the use of global position system (GPS) equipped smartphones. Two algorithms that use data from GPS equipped smartphones to estimate arterial traffic conditions are presented, analyzed and compared. The algorithms are based on Logistic Regression and Spatio-Temporal Auto Regressive Moving Average (STARMA), respectively. Each algorithm contains a learning component, which...

An Adaptive Routing System for Location-Aware Mobile Devices on the Road Network

Borokhov, Paul
Blandin, Sébastien
Samaranayake, Samitha
Goldschmidt, Olivier
Bayen, Alexandre M.
2011

As congestion problems become a greater concern and negatively impact society, solutions which alleviate them are needed to improve the performance of the transportation system. Routing systems which take into account the travel-time experienced by the driver have been largely unexplored in the domain of adaptive routing. In this article, we present a system which enables users of smartphones to obtain directions generated using an algorithm which provides an optimal routing policy for reliable on-time arrival; that is, directions which seek to maximize the probability of arriving to the...

Optimal Decomposition of Travel Times Measured by Probe Vehicles Using a Statistical Traffic Flow Model

Hofleitner, A.
Bayen, A.
2011

Sparse location measurements of probe vehicles are a promising data source for arterial traffic monitoring. One common challenge in processing this source of data is that vehicles are sampled infrequently (on the order of once per minute), which means that many vehicles will travel several links of the network between consecutive measurements. In this article, we propose an optimal decomposition of path travel times of probe vehicles to link travel times for each link traversed. From a model of arterial traffic dynamics, we derive probability distributions of travel times. We prove that...

Analytical and Grid-Free Solutions to the Lighthill–Whitham–Richards Traffic Flow Model

Mazaré, Pierre-Emmanuel
Dehwah, Ahmad H.
Claudel, Christian G.
Bayen, Alexandre M.
2011

In this article, we propose a computational method for solving the Lighthill–Whitham–Richards (LWR) partial differential equation (PDE) semi-analytically for arbitrary piecewise-constant initial and boundary conditions, and for arbitrary concave fundamental diagrams. With these assumptions, we show that the solution to the LWR PDE at any location and time can be computed exactly and semi-analytically for a very low computational cost using the cumulative number of vehicles formulation of the problem. We implement the proposed computational method on a representative traffic flow scenario...