30 research outputs found
Resilience of Traffic Networks with Partially Controlled Routing
This paper investigates the use of Infrastructure-To-Vehicle (I2V)
communication to generate routing suggestions for drivers in transportation
systems, with the goal of optimizing a measure of overall network congestion.
We define link-wise levels of trust to tolerate the non-cooperative behavior of
part of the driver population, and we propose a real-time optimization
mechanism that adapts to the instantaneous network conditions and to sudden
changes in the levels of trust. Our framework allows us to quantify the
improvement in travel time in relation to the degree at which drivers follow
the routing suggestions. We then study the resilience of the system, measured
as the smallest change in routing choices that results in roads reaching their
maximum capacity. Interestingly, our findings suggest that fluctuations in the
extent to which drivers follow the provided routing suggestions can cause
failures of certain links. These results imply that the benefits of using
Infrastructure-To-Vehicle communication come at the cost of new fragilities,
that should be appropriately addressed in order to guarantee the reliable
operation of the infrastructure.Comment: Accepted for presentation at the IEEE 2019 American Control
Conferenc
Price of Anarchy for Non-atomic Congestion Games with Stochastic Demands
We generalize the notions of user equilibrium and system optimum to
non-atomic congestion games with stochastic demands. We establish upper bounds
on the price of anarchy for three different settings of link cost functions and
demand distributions, namely, (a) affine cost functions and general
distributions, (b) polynomial cost functions and general positive-valued
distributions, and (c) polynomial cost functions and the normal distributions.
All the upper bounds are tight in some special cases, including the case of
deterministic demands.Comment: 31 page
Altruistic Autonomy: Beating Congestion on Shared Roads
Traffic congestion has large economic and social costs. The introduction of
autonomous vehicles can potentially reduce this congestion, both by increasing
network throughput and by enabling a social planner to incentivize users of
autonomous vehicles to take longer routes that can alleviate congestion on more
direct roads. We formalize the effects of altruistic autonomy on roads shared
between human drivers and autonomous vehicles. In this work, we develop a
formal model of road congestion on shared roads based on the fundamental
diagram of traffic. We consider a network of parallel roads and provide
algorithms that compute optimal equilibria that are robust to additional
unforeseen demand. We further plan for optimal routings when users have varying
degrees of altruism. We find that even with arbitrarily small altruism, total
latency can be unboundedly better than without altruism, and that the best
selfish equilibrium can be unboundedly better than the worst selfish
equilibrium. We validate our theoretical results through microscopic traffic
simulations and show average latency decrease of a factor of 4 from worst-case
selfish equilibrium to the optimal equilibrium when autonomous vehicles are
altruistic.Comment: Accepted to Workshop on the Algorithmic Foundations of Robotics
(WAFR) 201
Interplay between security providers, consumers, and attackers: a weighted congestion game approach
Network users can choose among different security solutions to protect their data. Those solutions are offered by competing providers, with possibly different performance and price levels. In this paper, we model the interactions among users as a noncooperative game, with a negative externality coming from the fact that attackers target popular systems to maximize their expected gain. Using a nonatomic weighted congestion game model for user interactions, we prove the existence and uniqueness of a user equilibrium, compute the corresponding Price of Anarchy, that is the loss of efficiency due to user selfishness, and investigate some consequences for the (higher-level) pricing game played by security providers.Game theory;Weighted games; Security
Atomic congestion games with random players : network equilibrium and the price of anarchy
In this paper, we present a new model of congestion games with finite and random number of players, and an analytical method to compute the random path and link flows. We study the equilibrium condition, reformulate it as an equivalent variational inequality problem, and establish the existence and non-uniqueness of the equilibria. We also upper bound the price of anarchy with affine cost functions to characterize the quality of the equilibria. The upper bound is tight in some special cases, including the case of deterministic players. Finally a general lower bound is also provided
Bounding the efficiency of road pricing
This paper deals with the following question associated with congestion pricing in a general network with either fixed or elastic travel demand: what is the maximum efficiency loss of a general second-best pricing scheme due to inexact marginal-cost pricing in comparison with the first-best pricing or system optimum case? A formal answer to this question is provided by establishing an inefficiency bound associated with a given road pricing scheme. An application of the methods is provided for the practical trial-and-error implementation of marginal-cost pricing with unknown demand functions