Traffic Theory

Freeway Traffic Oscillations: Observations and Predictions

Mauch, Michael
Cassidy, Michael J.
Taylor, Michael A. P.
2002

Freeway traffic was observed over multiple days and was found to display certain regular features. Oscillations arose only in queues; they had periods of several minutes; and their amplitudes stabilized as they propagated upstream. They propagated at a nearly constant speed of about 22 to 24 kilometers per hour, independent of the location within the queues and the flow measured there; this was observed for a number of locations and for queued flows ranging from about 2,000 to 850 vehicles per hour per lane. The effects of the oscillations were not felt downstream of the bottleneck. Thus,...

Fingerprinting Traffic from Static Freeway Sensors

Munoz, Juan Carlos
Daganzo, Carlos F.
2002

Ask most commuters and they will agree that congestion has reached an intolerable level. To reduce this congestion, engineers need detailed traffic information. Highly detailed information is also prized by traffic scientists, as a prerequisite to improve current traffic theories. Ideally, engineers and scientists would like to obtain from field data the position of each vehicle on a particular facility at every moment in time. The technology to record space-time vehicle trajectories on a massive scale is in its infancy; therefore, analysts must work with much less data. Many freeways are...

System Optimum and Pricing for the Day-Long Commute with Distributed Demand, Autos and Transit

Daganzo, Carlos F.
2013

The day-long system optimum (SO) commute for an urban area served by auto and transit is modeled as an auto bottleneck with a capacitated transit bypass. A public agency manages the system’s capacities optimally. Commuters are identical except for the times at which they wish to complete their morning trips and start their evening trips, which are given by an arbitrary joint distribution. They value unpunctuality – their lateness or earliness relative to their wish times – with a common penalty function. They must use the same mode for both trips. Commuters are assigned personalized mode...

Synergies of Combining Demand and Supply-Side Measures to Manage Congested Streets

Itani, Ibrahim
Cassidy, Michael J.
Daganzo, Carlos
2021

An agent-based, multichannel simulation of a downtown area reveals the impacts of both time-shifting traffic demand with congestion pricing, and supplying extra capacity by banning left turns. The downtown street network was idealized, and loosely resembles central Los Angeles. On the demand-side, prices were set based on time-of-day and distance traveled. On the supply side, left-turn maneuvers were prohibited at all intersections on the network. Although both traffic management measures reduced travel costs when used alone, the left-turn ban was much less effective than pricing. When...

Path and Travel Time Inference from GPS Probe Vehicle Data

Hunter, Timothy
Herring, Ryan
Bayen, Alexandre M.
2009

We consider the problem of estimating real-time traffic conditions from sparse, noisy GPS probe vehicle data. We specifically address arterial roads, which are also known as the secondary road network (highways are considered the primary road network). We consider several estimation problems: historical traffic patterns, real-time traffic conditions, and forecasting future traffic conditions. We assume that the data available for these estimation problems is a small set of sparsely traced vehicle trajectories, which represents a small fraction of the total vehicle flow through the network. We...

Zero-Shot Autonomous Vehicle Policy Transfer: From Simulation to Real-World via Adversarial Learning

Chalaki, Behdad
Beaver, Logan E.
Remer, Ben
Jang, Kathy
Vinitsky, Eugene
Bayen, Alexandre
Malikopoulos, Andreas A.
2020

In this article, we demonstrate a zero-shot transfer of an autonomous driving policy from simulation to University of Delaware's scaled smart city with adversarial multi-agent reinforcement learning, in which an adversary attempts to decrease the net reward by perturbing both the inputs and outputs of the autonomous vehicles during training. We train the autonomous vehicles to coordinate with each other while crossing a roundabout in the presence of an adversary in simulation. The adversarial policy successfully reproduces the simulated behavior and incidentally outperforms, in terms of...

Adjoint-Based Control of a New Eulerian Network Model of Air Traffic Flow

Bayen, A.M.
Raffard, R.L.
Tomlin, C.J.
2006

An Eulerian network model for air traffic flow in the National Airspace System is developed and used to design flow control schemes which could be used by Air Traffic Controllers to optimize traffic flow. The model relies on a modified version of the Lighthill-Whitham-Richards (LWR) partial differential equation (PDE), which contains a velocity control term inside the divergence operator. This PDE can be related to aircraft count, which is a key metric in air traffic control. An analytical solution to the LWR PDE is constructed for a benchmark problem, to assess the gridsize required to...

Theory of Highway Traffic Signals

Newell, Gordon F.
1989

This report gives a comprehensive survey of the theory of highway traffic signals including isolated signals, one-way arterials, two-way arterials, and networks, limited however, to the common right angle junctions. The emphasis is on the logistics of control strategies rather than recipes for implementation. It is anticipated, however, that the implementation of some of the strategies described here will give substantial reductions in delays as compared with existing procedures.

Theory of Highway Traffic Flow: 1945 to 1965

Newell, Gordon F.
1995

Although we lack a complete theory of the motion of individual cars, there are many simple facts that even the most inexperienced driver knows and there are others which we could determine through experiment if we thought these facts were worth the effort required to find them. The lack of such a theory however, should not deter us from constructing a framework of possible theories consistent with what is known and seeing if such an incomplete theory can give any useful information about the gross aspects of traffic.

Reachability Analysis for FollowerStopper: Safety Analysis and Experimental Results

Chou, Fang-Chieh
Gibson, Marsalis
Bhadani, Rahul
Bayen, Alexandre M.
Sprinkle, Jonathan M.
2021

Motivated by earlier work and the developer of a new algorithm, the FollowerStopper, this article uses reachability analysis to verify the safety of the FollowerStopper algorithm, which is a controller designed for dampening stop-and-go traffic waves. With more than 1100 miles of driving data collected by our physical platform, we validate our analysis results by comparing it to human driving behaviors. The FollowerStopper controller has been demonstrated to dampen stop-and-go traffic waves at low speed, but previous analysis on its relative safety has been limited to upper and lower...