A decentralized control strategy for freeway regulation

A multilevel decentralized control scheme, the cascading technique, with application to the regulation of traffic on an urban freeway is presented. Performance of the decentralized system is compared to the performance of a centralized and a fixed time control structure. It is shown that the decentralized structure performs better than the centralized structure when incidents (lane closures) occur on the freeway. The freeway is modeled in terms of the aggregate variables section density and section speed, and is considered as a system of interconnected subsystems.     

Microscopic Analysis of Cellular Automata Based Traffic Flow Models and an Improved Model

Abstract

A large number of cellular automata (CA) based traffic flow models have been proposed in the recent past. Often, the speed‐flow‐density relations obtained from these models are only presented and their apparent similarities with observed relations are cited as reasons for considering them as valid models of traffic flow. Hardly any attempt has been made to comprehensively study the microscopic properties (like time‐headway distribution, acceleration noise, stability in car‐following situations, etc.) of the simulated streams. This article proposes a framework for such evaluations. The article also presents the results from the evaluation of six existing CA‐based models. The results show that none of them satisfy all the properties. A new model proposed by the authors to overcome these shortcomings is briefly presented, and results supporting the improved performance of the proposed model are also provided.     

Strategies of state and local government in management of urban transport problems – A case of Delhi

In India, different layers of Government control different policy instruments to tackle transport externalities which might result in coordination problems and possible efficiency losses. This paper, therefore, addresses the coordination problem resulting from the division of policy instruments between two different government levels that face different types of externalities in varying degrees of magnitude in the urban transport sector by developing three types of theoretical models: the Full Control Centralised Model where the state government has full control over all pricing instrument; a Nash equilibrium model where each of the government levels controls only one instrument and takes the behaviour of the other as given; and a Stackelberg equilibrium mode where the behaviour of the state government is influenced by the fact that one of the price instruments is controlled by the local government. With an empirical illustration of the model for Delhi, the paper finds that since there are many interactions and many externalities between the two levels of government, a division of roles between them does not guarantee an efficient pricing outcome and the efficiency of pricing would depend on the institutional set up and on the correspondence between the objective functions of the two government levels.