Equilibrium predictions in transportation markets: The state of the art

The task of predicting the short run equilibrium of a transportation market is central to the study of many transportation problems. In this paper we review the different approaches and methodologies that have been proposed to deal with the equilibrium problem in transportation markets. The problem is formulated in the most general way possible and its fundamental characteristics are analyzed. Then, different mathematical characterizations of transportation market and traffic flow equilibrium in networks are reviewed. Various available results are presented and analyzed. Finally, a discussion is given of alternative computational procedures for dealing with multiclass problems.     

Adolescents and their aspirations for private car-based transport

Transportation - The need to transition away from the current car-dominated transport system is well documented in sustainability, health and transportation literatures. Despite growing interest in...     

Stochastic Monte Carlo simulations of the pantograph–catenary dynamic interaction to allow for uncertainties introduced during catenary installation

The simulation of the pantograph–catenary dynamic interaction is at present mainly based on deterministic approaches. However, any errors made during the catenary stringing process are sources of variability that can affect the dynamic performance of the system. In this paper, we analyse the influence of dropper length, dropper spacing and support height errors on the current collection quality by applying a classic Monte Carlo method to obtain the probability density functions of several output quantities. The effects of installation errors are also studied for a range of train speeds. Finally, the pre-sag that, on average, produces the best behaviour of the system is identified, allowing for the uncertainty in the catenary installation. The results obtained show the convenience to consider variability in pantograph–catenary dynamic simulations.     

Observability in traffic networks. Plate scanning added by counting information

The paper deals with the observability problem in traffic networks, including route, origin?Cdestination and link flows, based on number plate scanning and link flow observations. A revision of the main observability concepts and methods is done using a small network. Starting with the full observability of the network based only on number plate scanning on some links, the number of scanned links is reduced and replaced by counted link flows, but keeping the full observability of all flows in the network. In this way, the cost can be substantially reduced. To this end, several methods are given and discussed, and two small and one real case of networks are used to illustrate the proposed methodologies. Finally, some conclusions and final recommendations are included.     

A model of optimal transport maintenance with demand responsiveness

Maintenance activities can be performed throughout the lifetime of a particular facility or piece of equipment, thereby affecting its quality in a continuous fashion. It is assumed in this paper that quality of a facility is determined by natural factors, rate of use and maintenance investments while demand for the facility is assumed to be a function of its quality. A dynamic optimization model in the form of a simple linear optimal control problem is then developed in order to determine optimal maintenance policies under these circumstances. Bang-bang and singular policies are derived and given economic interpretations. An algorithm is presented for numerical solution of the Pontryagin necessary conditions. Finally, sufficiency conditions are obtained for the model structure considered.