Anthony E. Ohazulike - Academia.edu (original) (raw)
Papers by Anthony E. Ohazulike
2012 IEEE 75th Vehicular Technology Conference (VTC Spring), 2012
In addition to safety, Vehicular Ad-hoc Networks (VANETs) enable the development of new informati... more In addition to safety, Vehicular Ad-hoc Networks (VANETs) enable the development of new information-rich applications that disseminate relevant data to vehicles. One key challenge in such networks is to use the available bandwidth efficiently when there is: (i) a short connectivity time due to the rapidly changing road environment, and (ii) bandwidth congestion due to continuous collection and dissemination of
Traffic externalities are increasingly becoming unbearable in most cities of the world. Congestio... more Traffic externalities are increasingly becoming unbearable in most cities of the world. Congestion has caused many countries huge loss in man-hours which translates to huge amounts of money being lost every single day. Air qualities in most cities are not in accordance with the stipulated standards. This results in a severe health issues to innocent residents and endangers the existence of future generations. Restlessness and nuisance caused by unacceptable high noise level associated with road traffic are also increasingly becoming a point of concern by both inhabitants and the government. In most cities, accident and fatality rates resulting from road traffic are on the increase. By allowing much traffic or heavy duty vehicles on small pavements dilapidates these pavements, and this translates to the cost of road (or pavement) maintenance which is generally high. It has been shown from the famous Braess’ paradox that combating congestion by adding more infrastructures can worsen t...
Using a game theoretical approach, we develop a pricing scheme that internalizes multiple traffic... more Using a game theoretical approach, we develop a pricing scheme that internalizes multiple traffic externalities. Further, we extend the single authority road pricing scheme to a scheme with multiple actors/stakeholders or regions. Road users’ interests are represented in the upper and the same level as the decision makers, thus, making them active players in the toll setting game. Having shown that pure Nash equilibrium (NE) toll may not exist among the stakeholders (with likely opposing objectives), we design a mechanism that induces NE which coincides with system optimum.
A road pricing game is a game where various stakeholders and/or regions with different (and usual... more A road pricing game is a game where various stakeholders and/or regions with different (and usually conflicting) objectives compete for toll setting in a given transportation network to satisfy their individual objectives. We investigate some classical game theoretical solution concepts for the road pricing game. We establish results for the road pricing game so that stakeholders and/or regions playing such
Appl Phys Lett, 2012
Costs associated with traffic externalities such as congestion, air pollution, noise, safety, etce... more Costs associated with traffic externalities such as congestion, air pollution, noise, safety, etcetera are becoming “unbearable”. The Braess paradox shows that combating congestion by adding infrastructure may not improve traffic conditions, and geographical and/or financial constraints may not allow infrastructure expansion. Road pricing presents an alternative to combat the mentioned externalities. The traditional way of road pricing, namely; congestion charging,
By 2050, it is expected that more than 9 billion people will be living on Earth. Development will... more By 2050, it is expected that more than 9 billion people will be living on Earth. Development will reach to many places on Earth, demand for a better life will rise, car/vehicle ownership will increase, leading to high demand for road capacities and infrastructures, yet supply for these road capacities and infrastructures is not going to increase in the same rate as their demand. Further, this increase in vehicle ownership will escalate the traffic externalities such as congestion, emission, noise and so on. Due to financial, geographical, and political limitations, and the fact that even the expansion of the existing infrastructure may not lead to efficient use of transportation networks, it is envisaged that road pricing seems a viable option for achieving a more efficient use of the existing infrastructure. With all its potentials, road pricing has not gained all the supports it needed, mainly due to how the pricing schemes are developed and perceived by stakeholders and road users. We developed models for road pricing schemes taking into account the (usually) conflicting interests of various stakeholders and the road users, and all traffic externalities. For a just and acceptable road pricing scheme, we developed a novel idea from the concept of Nash equilibrium from game theory in the form of multi-stakeholder and multi-objective problems. We found that even in simple practical cases, that Nash equilibrium may not exist among the actors. This means that point of consensus might not be reached among stakeholders, an indication why talks on the adoption of road pricing have failed in many countries. To tackle this problem once and for all, we developed a mechanism that ensures that the point of consensus is reached among the stakeholders. The mechanism further ensures that the scheme adopted by these stakeholders is optimal for the society. To further address the issues of fairness and equity, and complications resulting from a link or kilometre-based charges, we developed a zone-based pricing scheme called an origin-destination based road pricing scheme. The scheme ensures efficient use of the road infrastructure by charging road users based on their origin and destination.
Genetic algorithms (GAs) are widely accepted by researchers as a method of solving multi-objectiv... more Genetic algorithms (GAs) are widely accepted by researchers as a method of solving multi-objective optimization problems (MOPs), at least for listing a high quality approximation of the Pareto front of a MOP. In traffic management, it has been long established that tolls can be used to optimally distribute traffic in a network with aim of combating some traffic externalities such as congestion, emission, noise, safety issues. Formulating the multi-objective toll problem as a one point solution problem fails to give the general overview of the objective space of the MOP. Therefore, in this paper we develop a game theoretic approach that gives the general overview of the objective space of the multiobjective problem and compare the results with those of the wellknown genetic algorithm non-dominated sorting genetic algorithm II (NSGA-II). Results show that the game theoretic approach presents a promising tool for solving multi-objective problems, since it produces similar non-dominated solutions as NSGA-II, indicating that competing objectives (or stakeholders in the game setting) can still produce Pareto optimal solutions. Most fascinating is that a range of non-dominated solutions is generated during the game, and almost all generated solutions are in the neighborhood of the Pareto set. This indicates that good solutions are generated very fast during the game.
We investigate a game theoretic approach as an alternative to the standard multi-objective optimi... more We investigate a game theoretic approach as an alternative to the standard multi-objective optimization models for road pricing. Assuming that various, partly conflicting traffic externalities (congestion, air pollution, noise, safety, etcetera) are represented by corresponding players acting on a common network, we obtain a non-cooperative game where each player pursues a different road pricing strategy to control a specific externality. The game is actually a Stackelberg game, but now with multiple leaders/actors in the upper level determining link tolls, and road users as followers in the lower level, adapting their route choice to the tolls imposed. This chapter reviews our earlier results on the game theoretic models, and the existence of Nash Equilibrium (NE). In order to cope with the fact that NE may not exist in the game, we propose a “first-best taxation” scheme, allowing the government to enforce pre-described NE (analogous first-best pricing schemes). We further discuss the stability of this taxing mechanism.
Costs associated with traffic externalities such as congestion, air pollution, noise, safety, etc... more Costs associated with traffic externalities such as congestion, air pollution, noise, safety, etcetera are becoming unbearable. The Braess paradox shows that combating congestion by adding infrastructure may not improve traffic conditions, and geographical and/or financial constraints may not allow infrastructure expansion. Road pricing presents an alternative to combat traffic externalities. The traditional way of road pricing, namely congestion charging, may create negative benefits for society. In this effect, we develop a flexible pricing scheme internalizing costs arising from all externalities. Using a game theoretical approach, we extend the single authority road pricing scheme to a pricing scheme with multiple authorities/regions (with likely contradicting objectives).
ABSTRACT By disseminating data through Vehicular Ad-hoc Networks (VANETs), vehicles are able to s... more ABSTRACT By disseminating data through Vehicular Ad-hoc Networks (VANETs), vehicles are able to share relevant sensor data to acquire information about accidents, traffic, and even pollution. Data relevance is measured by a utility function which considers the contextual information that vehicles currently have about their environment. To be effective, data dissemination protocols must cope with intermittent connectivity due to the high speeds of vehicles. Problems arise when not all data can be exchanged due to the limited time available. In this paper, we explore and compare two fundamentally distinct approaches to tackling this problem. The first aims to maximize the system efficiency. In contrast, the second trades efficiency by a fair data distribution over vehicles by means of Nash Bargaining as used in game theory. By means of an extensive simulation campaign, an approach relying on fairness is shown to outperform efficiency in terms of delivery ratio, Jain's fairness index, sum of utility gains, number of hops and number of files downloaded.
ABSTRACT To mitigate traffic externalities, we propose an origin–destination (OD) based road pric... more ABSTRACT To mitigate traffic externalities, we propose an origin–destination (OD) based road pricing model for traffic assignment problems. For elastic demand, we derive explicit optimal tolls for the OD-based pricing scheme. We also extend the model to a multi-period static traffic assignment (MSTA) where we derive analytically the route and OD-dependent tolls based on equilibrium conditions. We present some examples to show that the OD-based tolling scheme could improve the system welfare significantly, compared to the no-toll scenario (user equilibrium – UE).
2012 IEEE 75th Vehicular Technology Conference (VTC Spring), 2012
In addition to safety, Vehicular Ad-hoc Networks (VANETs) enable the development of new informati... more In addition to safety, Vehicular Ad-hoc Networks (VANETs) enable the development of new information-rich applications that disseminate relevant data to vehicles. One key challenge in such networks is to use the available bandwidth efficiently when there is: (i) a short connectivity time due to the rapidly changing road environment, and (ii) bandwidth congestion due to continuous collection and dissemination of
Traffic externalities are increasingly becoming unbearable in most cities of the world. Congestio... more Traffic externalities are increasingly becoming unbearable in most cities of the world. Congestion has caused many countries huge loss in man-hours which translates to huge amounts of money being lost every single day. Air qualities in most cities are not in accordance with the stipulated standards. This results in a severe health issues to innocent residents and endangers the existence of future generations. Restlessness and nuisance caused by unacceptable high noise level associated with road traffic are also increasingly becoming a point of concern by both inhabitants and the government. In most cities, accident and fatality rates resulting from road traffic are on the increase. By allowing much traffic or heavy duty vehicles on small pavements dilapidates these pavements, and this translates to the cost of road (or pavement) maintenance which is generally high. It has been shown from the famous Braess’ paradox that combating congestion by adding more infrastructures can worsen t...
Using a game theoretical approach, we develop a pricing scheme that internalizes multiple traffic... more Using a game theoretical approach, we develop a pricing scheme that internalizes multiple traffic externalities. Further, we extend the single authority road pricing scheme to a scheme with multiple actors/stakeholders or regions. Road users’ interests are represented in the upper and the same level as the decision makers, thus, making them active players in the toll setting game. Having shown that pure Nash equilibrium (NE) toll may not exist among the stakeholders (with likely opposing objectives), we design a mechanism that induces NE which coincides with system optimum.
A road pricing game is a game where various stakeholders and/or regions with different (and usual... more A road pricing game is a game where various stakeholders and/or regions with different (and usually conflicting) objectives compete for toll setting in a given transportation network to satisfy their individual objectives. We investigate some classical game theoretical solution concepts for the road pricing game. We establish results for the road pricing game so that stakeholders and/or regions playing such
Appl Phys Lett, 2012
Costs associated with traffic externalities such as congestion, air pollution, noise, safety, etce... more Costs associated with traffic externalities such as congestion, air pollution, noise, safety, etcetera are becoming “unbearable”. The Braess paradox shows that combating congestion by adding infrastructure may not improve traffic conditions, and geographical and/or financial constraints may not allow infrastructure expansion. Road pricing presents an alternative to combat the mentioned externalities. The traditional way of road pricing, namely; congestion charging,
By 2050, it is expected that more than 9 billion people will be living on Earth. Development will... more By 2050, it is expected that more than 9 billion people will be living on Earth. Development will reach to many places on Earth, demand for a better life will rise, car/vehicle ownership will increase, leading to high demand for road capacities and infrastructures, yet supply for these road capacities and infrastructures is not going to increase in the same rate as their demand. Further, this increase in vehicle ownership will escalate the traffic externalities such as congestion, emission, noise and so on. Due to financial, geographical, and political limitations, and the fact that even the expansion of the existing infrastructure may not lead to efficient use of transportation networks, it is envisaged that road pricing seems a viable option for achieving a more efficient use of the existing infrastructure. With all its potentials, road pricing has not gained all the supports it needed, mainly due to how the pricing schemes are developed and perceived by stakeholders and road users. We developed models for road pricing schemes taking into account the (usually) conflicting interests of various stakeholders and the road users, and all traffic externalities. For a just and acceptable road pricing scheme, we developed a novel idea from the concept of Nash equilibrium from game theory in the form of multi-stakeholder and multi-objective problems. We found that even in simple practical cases, that Nash equilibrium may not exist among the actors. This means that point of consensus might not be reached among stakeholders, an indication why talks on the adoption of road pricing have failed in many countries. To tackle this problem once and for all, we developed a mechanism that ensures that the point of consensus is reached among the stakeholders. The mechanism further ensures that the scheme adopted by these stakeholders is optimal for the society. To further address the issues of fairness and equity, and complications resulting from a link or kilometre-based charges, we developed a zone-based pricing scheme called an origin-destination based road pricing scheme. The scheme ensures efficient use of the road infrastructure by charging road users based on their origin and destination.
Genetic algorithms (GAs) are widely accepted by researchers as a method of solving multi-objectiv... more Genetic algorithms (GAs) are widely accepted by researchers as a method of solving multi-objective optimization problems (MOPs), at least for listing a high quality approximation of the Pareto front of a MOP. In traffic management, it has been long established that tolls can be used to optimally distribute traffic in a network with aim of combating some traffic externalities such as congestion, emission, noise, safety issues. Formulating the multi-objective toll problem as a one point solution problem fails to give the general overview of the objective space of the MOP. Therefore, in this paper we develop a game theoretic approach that gives the general overview of the objective space of the multiobjective problem and compare the results with those of the wellknown genetic algorithm non-dominated sorting genetic algorithm II (NSGA-II). Results show that the game theoretic approach presents a promising tool for solving multi-objective problems, since it produces similar non-dominated solutions as NSGA-II, indicating that competing objectives (or stakeholders in the game setting) can still produce Pareto optimal solutions. Most fascinating is that a range of non-dominated solutions is generated during the game, and almost all generated solutions are in the neighborhood of the Pareto set. This indicates that good solutions are generated very fast during the game.
We investigate a game theoretic approach as an alternative to the standard multi-objective optimi... more We investigate a game theoretic approach as an alternative to the standard multi-objective optimization models for road pricing. Assuming that various, partly conflicting traffic externalities (congestion, air pollution, noise, safety, etcetera) are represented by corresponding players acting on a common network, we obtain a non-cooperative game where each player pursues a different road pricing strategy to control a specific externality. The game is actually a Stackelberg game, but now with multiple leaders/actors in the upper level determining link tolls, and road users as followers in the lower level, adapting their route choice to the tolls imposed. This chapter reviews our earlier results on the game theoretic models, and the existence of Nash Equilibrium (NE). In order to cope with the fact that NE may not exist in the game, we propose a “first-best taxation” scheme, allowing the government to enforce pre-described NE (analogous first-best pricing schemes). We further discuss the stability of this taxing mechanism.
Costs associated with traffic externalities such as congestion, air pollution, noise, safety, etc... more Costs associated with traffic externalities such as congestion, air pollution, noise, safety, etcetera are becoming unbearable. The Braess paradox shows that combating congestion by adding infrastructure may not improve traffic conditions, and geographical and/or financial constraints may not allow infrastructure expansion. Road pricing presents an alternative to combat traffic externalities. The traditional way of road pricing, namely congestion charging, may create negative benefits for society. In this effect, we develop a flexible pricing scheme internalizing costs arising from all externalities. Using a game theoretical approach, we extend the single authority road pricing scheme to a pricing scheme with multiple authorities/regions (with likely contradicting objectives).
ABSTRACT By disseminating data through Vehicular Ad-hoc Networks (VANETs), vehicles are able to s... more ABSTRACT By disseminating data through Vehicular Ad-hoc Networks (VANETs), vehicles are able to share relevant sensor data to acquire information about accidents, traffic, and even pollution. Data relevance is measured by a utility function which considers the contextual information that vehicles currently have about their environment. To be effective, data dissemination protocols must cope with intermittent connectivity due to the high speeds of vehicles. Problems arise when not all data can be exchanged due to the limited time available. In this paper, we explore and compare two fundamentally distinct approaches to tackling this problem. The first aims to maximize the system efficiency. In contrast, the second trades efficiency by a fair data distribution over vehicles by means of Nash Bargaining as used in game theory. By means of an extensive simulation campaign, an approach relying on fairness is shown to outperform efficiency in terms of delivery ratio, Jain's fairness index, sum of utility gains, number of hops and number of files downloaded.
ABSTRACT To mitigate traffic externalities, we propose an origin–destination (OD) based road pric... more ABSTRACT To mitigate traffic externalities, we propose an origin–destination (OD) based road pricing model for traffic assignment problems. For elastic demand, we derive explicit optimal tolls for the OD-based pricing scheme. We also extend the model to a multi-period static traffic assignment (MSTA) where we derive analytically the route and OD-dependent tolls based on equilibrium conditions. We present some examples to show that the OD-based tolling scheme could improve the system welfare significantly, compared to the no-toll scenario (user equilibrium – UE).