Formulating and solving the network design problem by decomposition

The optimal transportation network design problem is formulated as a convex nonlinear programming problem and a solution method based on standard traffic assignment algorithms is presented. The technique can deal with network improvements which introduce new links, which increase the capacity of existing links, or which decrease the free-flow (uncongested) travel time on existing links (with or without simultaneously increasing link capacity). Preliminary computational experience with the method demonstrates that it is capable of solving very large problems with reasonable amounts of computer time.     

Impact of high occupancy vehicle lanes on carpooling behavior

High occupancy vehicle lanes have become an integral part of regional transportation planning. Their purpose is to increase ridesharing by offering a travel time advantage to multiple occupant vehicles. This paper examines the extent to which an HOV facility increases ridesharing. Using data from the Route 55 HOV facility in Orange Country, California, changes in the carpooling rate on Route 55 are compared to that of a control group of freeway commuters. The analysis shows that the carpooling rate among peak period commuters, and particularly those who use the entire length of the facility, has increased. However, there has been no significant increase in ridesharing among the entire population of Route 55 commuters. Results suggest that barriers to increased ridesharing are formidable, that travel time savings must be large in order to attract new carpoolers, and that further increases in capooling will likely require development of extensive HOV lane systems.     

An activity-based approach for scheduling multimodal transit services

This paper proposes a new activity-based transit assignment model for investigating the scheduling (or timetabling) problem of transit services in multi-modal transit networks. The proposed model can be used to generate the short-term and long-term timetables of multimodal transit lines for transit operations and service planning purposes. The interaction between transit timetables and passenger activity-travel scheduling behaviors is captured by the proposed model, as the activity and travel choices of transit passengers are considered explicitly in terms of departure time choice, activity/trip chain choices, activity duration choice, transit line and mode choices. A heuristic solution algorithm which combines the Hooke–Jeeves method and an iterative supply–demand equilibrium approach is developed to solve the proposed model. Two numerical examples are presented to illustrate the differences between the activity-based approach and the traditional trip-based method, together with comparison on the effects of optimal timetables with even and uneven headways. It is shown that the passenger travel scheduling pattern derived from the activity-based approach is significantly different from that obtained by the trip-based method, and that a demand-sensitive (with uneven headway) timetable is more efficient than an even-headway timetable.     

Short run fare elasticities for Bogotá’s BRT system: ridership responses to fare increases

Transportation - The fare policy of the BRT system in Bogotá, in order to cover its operating costs, has consisted of steadily fare increases, since its creation until 2012. To date, no study...     

Examining the effects of out-of-home and in-home constraints on leisure activity participation in different seasons of the year

Using multi-day, multi-period travel diaries data of 56 days (four waves of two-week diaries) for 67 individuals in Stockholm, this study aims to examine the effects of out-of-home and in-home constraints (e.g. teleworking, studying at home, doing the laundry, cleaning and taking care of other household member[s]) on individuals’ day-to-day leisure activity participation decisions in four different seasons. This study also aims to explore the effects of various types of working schedules (fixed, shift, partial- and full-flexible) on individuals’ decisions to participate in day-to-day leisure activities. A pooled model (56 days) and wave-specific models (14 days in each wave) are estimated by using dynamic ordered Probit models. The effects of various types of working schedules are estimated by using 28 days of two waves’ data. The results show that an individual’s leisure activity participation decision is significantly influenced by out-of-home work durations but not influenced by in-home constraints, regardless of any seasons. Individuals with shift working hours engage less in day-to-day leisure activities than other workers’ types in both spring and summer seasons. The thermal indicator significantly affects individuals’ leisure activity participation decisions during the autumn season. Individuals exhibit routine behaviour characterized by repeated decisions in participating in day-to-day leisure activities that can last up to 14 days, regardless of any seasons.     

A review of Australian traffic system design models

The demands for traffic infrastructure are increasing. Yet over the last decade investment in new infrastructure has decreased at all levels. Traffic systems designers are, therefore, being asked to be more accurate in their prediction of the impacts of changes, to analyse ever more complex situations and to extract more from the existing traffic system. This paper reviews developments in techniques for analysing the impacts of changes in the traffic system. It looks at intersection, route, network, parking lot and public transport design models that have been developed in Australia. Particular emphasis is given to the considerable developments in microcomputers and graphics and the impact these are having on the models. Future developments are also discussed.     

Selection of urban transportation systems

An information system is presented which identifies the transportation technologies suited to any one transportation need situation lying in a broad range of such situations. The system is concerned with people movement rather than goods movement. The user of the system specifies the nature and extent of demand, as well as certain service requirements. A transportation technology is identified as suited to a particular need situation when the technology meets the demand and the service requirements, and does so at reasonable cost. The technologies identified by the system as suited to a need situation must be examined to select the one best alternative. This final selection process is not part of the system. This system consists of two tables. Their use is described and examples are given. The procedure used to develop the tables is discussed. The system identifies new transportation technologies (PRT, AGT, etc.) as well as old.     

Developing a comprehensive programme for improving shipboard energy efficiency

This article identifies a set of fuel saving strategies designed to meet the needs of vessel owners and operators, and describes how the strategies can be combined into a comprehensive programme. The strategies are developed from over sixty potential fuel saving measures grouped on the basis of commonness of purpose and interdependency. These criteria reflect the finding that implementing certain strategies is a prerequisite to the success of other strategies, and the success of some strategies generates a need to implement other strategies. Operational strategies identified include: developing crew motivation for active participation in energy efficiency improvement programmes; altering ship speeds; reducing auxiliary load on main propulsion plant; improved matching of ship capacities and cargo volume; reducing miles traveled; and maximizing use of electronic navigation and communications aids. Physical plant modification strategies identified include: optimizing for reduced ship speeds; fuel switching, blending and modifying; hydrodynamic improvements to the hull and propeller; and improving thrust.     

Competition for the German regional rail passenger market 5 years after regionalization

The paper investigates the competition for regional passenger rail services in Germany from 1996 to 2000 by using data mainly provided by regional authorities. It analyses data on the level of network characteristics, contract life, the Länder (i.e. regions), competitive placing procedures, and their winners as well as achieved cost and services improvements. It finds that with competition being rare, the amount of competitively placed services declined until recently. Only about half of the regional authorities gained experience with competitive placings, which points at the expertise deficit of these bodies. A diverse picture on competitive placings' characteristics such as network size and contract life appears. State-owned carrier DB AG remains the dominant player as it could win the majority of the competitively procured services. Private companies have played a minor role in the game up to now. Accomplished reduction of subsidies and improved service quality respectively provide an indication of the potential for enhancing efficiency in this market.     

Agricultural vehicles and sustainable safe road traffic: solving conflicts on arterial highways

Addressing the issues of traffic safety in rural areas presents a constant challenge. The mix of light and heavy vehicles and the considerable differences in speed among these traffic participants result in high risks and delays for the faster vehicles. Agricultural vehicles (AVs) in particular have such an impact on traffic, especially when using arterial highways. This paper reviews the problems of safety and delays that AVs cause on arterial highways, and the appropriate mitigation. The concept of 'sustainable safety' in The Netherlands focuses on these problems, because of the proposed construction of parallel roads alongside all arterial highways. However, Dutch accident statistics cannot justify the high costs for the construction of parallel roads alongside 7000 km of arterial highways. Delays experienced by fast traffic are another reason for separating AVs from other road users with parallel roads. Alternative measures alongside the arterial highway, such as passing bays, restricting AVs to travelling at off-peak only and improving the conspicuity of the AVs, may be more cost-effective ways of reducing delays and/or improving traffic safety on arterial highways. Another solution may be to eliminate the need for AVs to use the arterial highway by altering their routes. For this purpose, land reallocation projects (as practised in Holland) can provide a useful tool.