Jose Luis Moura

Urban freight transport and city logistics policies: Indications from Rome, Barcelona, and Santander

ABSTRACT This article compares the characteristics of urban freight transport in Rome, Barcelona, and Santander and the logistics measures being implemented in the three cities. The analysis is based on three similar surveys carried out in recent years involving interviews with retailers and transport operators. The main objective of this study is to evaluate the similarities and differences in terms of spatial patterns, current regulations, socioeconomic characteristics, commercial structures, freight demand characteristics, and current distribution patterns followed by different transport and logistics operators. The study shows that there are some different patterns of urban distribution that need to be taken into account when implementing city logistics measures in order to meet desired sustainability goals.

Bi-Level Mathematical Programming Model for Locating Bus Stops and Optimizing Frequencies

This paper proposes a model for locating bus stops and optimizing bus frequencies in congested local public transport networks. The analysis addresses the issue of reducing the overall costs of operating a transport system, including costs associated with provision of services and bus stop construction, using a bi-level mathematical programming method. The upper level defines the overall cost of the system, which must be kept to a minimum taking into account operational restrictions, and the lower level defines a behavioral model for system users. The suggested model mixes optimization and simulation and allows supply and demand to be linked; this ensures consistency between equilibrium flows and bus frequencies and between equilibrium flows and the distances between bus stops calculated at each iteration of the algorithm.

Bus Stop Location under Different Levels of Network Congestion and Elastic Demand

Abstract The article analyses optimal bus stop locations under different network congestion levels applying a bi-level optimisation model, covering an upper level minimizing an overall cost function (Social Cost) and a lower level that includes a modal split assignment model. This model is applied to Santander city (Spain) under a range of demand levels, starting from very low to high congestion, representing the evolution of variables in each case and analysing different solutions. The optimal distances between stops obtained for each demand and congestion level indicate that very low demands produce wider spaces. However, as demand increases, accessibility to public transport service should be increased and then spacing between bus stops drops to 360 metres.

Costing School Transport in Spain

Abstract School transport in Spain is conceived administratively as a regular, but special, public transport service financed by the Spanish regional governments through private sector contracts adjudicated by public tendering. As such it has two special features in comparison to systems elsewhere. First, larger operators use conventional buses (rather than special school buses) and these can also be used for regular services during school hours. Second, as these are regional services, often only regional operators bid for these tenders, so contract assignment resembles a bargaining process between operators and administrations, tempering an adequate operation of the market. This problem is common to all Spanish regions. The situation described has generated high costs (i.e. 15% increase in contract costs in the past year although the number of contracts did not vary significantly). For this reason the Government of Cantabria commissioned research to examine the problem. A simple cost allocation model allowed us to detect that school transport costs were, on average, approximately 18% higher than what could be deemed reasonable. This article describes the problem, the reasons why it has occurred and explains the model built to examine it in certain detail. It also shows the immediate consequences of its application (i.e. the reaction of the main operators and their changed strategy) and the steps taken by the Regional Government, based on our results, to ensure a proper operation of the market in the future.

Public Transport Line Assignment Model to Dual-Berth Bus Stops

Bunching at bus stops can be a major problem for traffic and passengers if bus arrivals are not well distributed. Arrivals can be better staggered if bus stops are divided into more than one berth. This article presents a methodology using a bilevel optimization model for assigning public transport routes to bus stops that have been divided to increase their capacity. The upper level minimizes the user costs, and the lower level applies a public transport assignment model under congestion conditions. The model is first applied to an example network to compare different assignment configurations; it is then applied to a real case in the city of Santander, Spain. The quantified benefits of an optimal route-stop assignment show increases of 10% in average bus speed and reductions of 5% in user costs.

A simulation tool for bicycle sharing systems in multimodal networks

This paper presents a methodology for modelling an urban transport system, integrating public bicycles in a multi-modal network. A bike cost function that reproduces the effect of slopes on cycling speeds is proposed. Also, the effect of traffic levels on the attractiveness of cycling routes is taken into account. The model applies the modal split and network assignment phases in a multimodal network with different classes of users. It has been verified over a test network and then validated by applying it to a real case in the city of Santander in Spain. The results obtained make this model a useful decision-making tool to encourage the use of the public bicycle from a sustainable development point of view.

Planning school transport: design of routes with flexible school opening times

Abstract This paper puts forward a methodology for designing a system for school transport which, apart from designing routes, specifies school opening times. Traditionally school opening times have always been identical in the same area meaning many buses have to be used at the same time. This paper suggests the staggering of school opening times in order to minimise the number of buses and thereby reduce the enormous costs involved in running them. The methodology is based on: a first phase which addresses the classic routing problem by using mixed integer lineal programming and a second phase which uses bi-level programming to find the vector for school opening times, which, when staying within the constraints of the problem, minimises the direct costs of the system. The upper level represents the evaluation of the system costs and the lower level finds the best combination of optimum routes for the same bus.

Transition between Signal Timing Plans: A Methodological and Analytical Overview

Abstract The transition phase is generally defined as the process of switching from one timing plan to another; this process may include changes in offset, phase split or cycle length until coordination for a new timing plan is reached once again. As noted in the literature, transition phases between timing plans may lead to severe disruptions of traffic flow, resulting in potentially lasting effects. The aim of this paper is to comprehensively review, classify and analyse the literature regarding transition between different timing plans to highlight existing research gaps and give researchers a starting point to continue contributing with solutions to the transition problem. Regarding transition approaches, a gap concerning mathematical approaches was deemed significant as a transition could be greatly benefited by simultaneously optimising more than one operational measure of effectiveness through multi-objective mathematical models. Moreover, in the analysis of applied approaches, Shortway algorithms generally outperformed other practical methods under different scenarios.

Analytical model for calibrating delay at congested bus stops

Abstract A model is proposed to calculate the overall operating and delay times spent at bus stops due to passenger boarding and alighting and the time lost to queuing caused by bus stop saturation. A formula for line demand at each stop and the interaction between the buses themselves is proposed and applied to different bus stops depending on the number of available berths. The application of this model has quantified significant operational delays suffered by users and operator due to consecutive bus arrival at stops, even with flows below bus stop capacity.

Using O–D matrices for decision making in road network management

Abstract This article uses a real example to demonstrate the importance of mobility modelling (objective criteria) on correctly planned investments in infrastructure. Some radical conclusions are drawn which differ greatly from those suggested by more subjective mental models. Strategic developments on inter-urban networks are evaluated by applying a mobility model including a model for estimating O–D matrices based on traffic counts and a model for the optimal location of traffic counting stations at the same time as a population accessibility model. An important decision making tool is provided for planning investments in road infrastructure by rationalising the high public spending required for this type of work. The models are applied to various possible projects at determined points on a regional road network in the Autonomous Community of Cantabria (Northern Spain) following the proposals and demands of different social and political groups. The models find a 68% reduction in the number of links req...