Optimization of headway, stops, and time points considering stochastic bus arrivals

With the capability to transport a large number of passengers, public transit acts as an important role in congestion reduction and energy conservation. However, the quality of transit service, in terms of accessibility and reliability, significantly affects model choices of transit users. Unreliable service will cause extra wait time to passengers because of headway irregularity at stops, as well as extra recovery time built into schedule and additional cost to operators because of ineffective utilization of allocated resources. This study aims to optimize service planning and improve reliability for a fixed bus route, yielding maximum operator’s profit. Three models are developed to deal with different systems. Model I focuses on a feeder transit route with many-to-one demand patterns, which serves to prove the concept that headway variance has a significant influence on the operator profit and optimal stop/headway configuration. It optimizes stop spacing and headway for maximum operator’s profit under the consideration of demand elasticity. With a discrete modelling approach, Model II optimizes actual stop locations and dispatching headway for a conventional transit route with many-to-many demand patterns. It is applied for maximizing operator profit and improving service reliability considering elasticity of demand with respect to travel time. In the second model, the headway variance is formulated to take into account the interrelationship of link travel time variation and demand fluctuation over space and time. Model III is developed to optimize the number and locations of time points with a headway-based vehicle controlling approach. It integrates a simulation model and an optimization model with two objectives - minimizing average user cost and minimizing average operator cost. With the optimal result generated by Model II, the final model further enhances system performance in terms of headway regularity. Three case studies are conducted to test the applicability of the developed models in a real world bus route, whose demand distribution is adjusted to fit the data needs for each model. It is found that ignoring the impact of headway variance in service planning optimization leads to poor decision making (i.e., not cost-effective). The results show that the optimized headway and stops effectively improve operator’s profit and elevate system level of service in terms of reduced headway coefficient of variation at stops. Moreover, the developed models are flexible for both planning of a new bus route and modifying an existing bus route for better performance

Improving bus service reliability: The Singapore experience

In February 2014, Singapore embarked on a 2-year trial of a Bus Service Reliability Framework (BSRF) to improve en-route bus regularity and reduce instances of bus bunching and prolonged waiting times. Based on London's Quality Incentive Contract, the Singapore model also imposes penalties or provides incentives to operators for increases/reductions of Excess Wait Time (EWT) beyond a certain route-specific baseline. Drawing on insights derived from research on performance-based contracts, this paper describes some key considerations surrounding this particular innovation in Singapore's overall bus regulatory framework. We also discuss an important advancement in our understanding of how bus users value reliability improvements through estimates obtained from stated preference data. At the same time, early indications from the trial have been encouraging

Costs of Interchange: A Review of the Literature.

Interchange within mode influences the demand for that mode through the effect it has on time spent waiting, time spent transferring between vehicles and the inconvenience and risks involved, whilst interchange between modes has additional implications in terms of information provision, through ticketing and co-ordination. The valuation and behavioural impact of each of these factors will vary with an individual’s socio-economic and trip characteristics as well as with the precise features of the interchange. A reduction in the costs of interchange brought about by an improvement to any of the above factors will lead to increasingly ‘seamless journeys’ and such benefits which must be quantified. Indeed, this issue has been identified as an area of key importance in the Government’s Transport White Paper (DETR, 1998a) which states: Quick and easy interchange is essential to compete with the convenience of car use. This message was reiterated by the draft guidance for Local Transport Plans (DETR, 1998b), which called for: more through-ticketing, better connections and co-ordination of services, wider availability of information and improved waiting facilities. Rather than being perceived simply as a barrier to travel, quality interchange is now also being regarded as an opportunity to create new journey opportunities. A recent report on the subject of interchange (Colin Buchanan and Partners, 1998) claimed that : It will become more sensible and economic to base public transport networks around the concept of interchange rather than the alternative of trying to avoid it. whilst in response to the diffuse travel patterns made possible by increased car availability, CIT (1998) commented: people should readily be able to complete a myriad of journeys by changing services (and modes) if a through facility is not available. Ease of interchange should be something we take for granted. Regardless of the precise direction in which transport policy and public transport provision develop, practical constraints and the fact that the most heavily trafficked routes tend to have through services places limitations on the extent to which the need to interchange can be reduced whilst no matter how fully integrated different modes of transport are the need to transfer between them cannot be removed. In contrast, the need to change would inevitably increase with the adoption of a practice of building networks around interchange to create new journey opportunities. However, there is considerable scope to improve existing interchange situations or to design new ones which impose minimum costs. Although previous empirical research has focused on the need to interchange or not, and this remains important, it is essential that research is also directed at improvements which facilitate interchange.The aims of this study, as set out in the terms of reference, are centred around the demand side response to interchange rather than the technical supply side issues relating to improving interchange and integration which have been covered in other studies (Colin Buchanan and Partners, 1998; CIT, 1998). The objectives are: to explore the extent to which the reality and perception of interchange deters public transport use, absolutely and in relation to other deterrents to investigate how public transport users perceive interchange; how they make choices and trade-offs in travel cost and time and the influence of interchange attributes (e.g. information, through ticketing) on those choices to assess which components of interchange act as the greatest deterrent to travel to investigate the extent to which interchange penalties vary according to journey purpose, distance and time of travel (or other factors)

Understanding bus service reliability : a practical framework using AVL/APC data

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2006.Includes bibliographical references (leaves 141-142).Service reliability on a transit system can have significant impacts on its provider and both existing and potential users. To passengers, unreliable service affects their perception of service quality and transit utility compared to other mode choices, while to transit agencies, this translates to loss of ridership and revenues and higher costs to provide additional service to compensate for poor service operations. The introduction of technologies such as Automatic Vehicle Location (AVL) and Automatic Passenger Counters (APC) provides the opportunity to gather large sets of data at relatively low cost and evaluate service to improve performance, schedule planning and operations control. This thesis presents a comprehensive review of key elements of service reliability, focused on the measures of reliability, the causes of unreliability and the application of strategies to improve service. The most significant causes of service reliability are presented: deviations at terminals, passenger loads, running times, environmental factors (or externalities) and operator behavior. Each is reviewed in terms of how they impact service and the complexities and interrelationship between different causes are explored. Also reviewed are the potential preventive and corrective strategies, and the links between the causes of service unreliability and best strategy according to the source of problems. A practical framework is developed to assess service reliability, exploring the uses of Automated Data Collection (ADC) systems to characterize service reliability and evaluate the causes of unreliability that may exist. Its goal is to serve as a guide for transit agencies to begin to analyze the large sets of data available from these systemsto evaluate performance and implement efficient strategies to improve service planning and operations. The proposed framework consists of three blocks: 1) characterization of service reliability through service measures and performance reports; 2) identification of causes of reliability problems; and 3) selection of strategies which target critical causes of unreliability to improve service. Characterization of service reliability involves examining five key elements an agency should analyze: a) data inputs, b) output calculations, c) service measures, d) threshold values, and e) performance reports. Identifying the causes of unreliability includes two sequential processes to infer the causes of service reliability problems. The first focuses on deviations at terminals, because good on-time performance and headway adherence is expected at the terminals and deviations at this point tend to propagate down the route and create further reliability problems. The second process examines deviations at other points on the route, and follows a set of steps to infer the causes of unreliability: initial deviations at terminal, passenger loads, poor schedule planning, operator behavior and externalities. Application of strategies includes an assessment of the best strategies to prevent reliability problems and reduce the impacts on service performance, based on the results of the previous analysis. The application of the proposed framework on the Silver Line Washington Street in Boston (MA) revealed that variability of running times and headway distributions are high. This indicates that bus arrivals and passenger wait times on this route are unpredictable and travel times are irregular. As a Bus Rapid Transit route,which is suppose to provide bus service with rail transit quality, headway adherence is poor on this route, with a tendency for buses to bunch together or leave gaps in service. Further analysis revealed that service reliability has recently deteriorated as a result of the implementation of a new Automatic Fare Collection (AFC) system. The new fare collection system presented delays in the boarding process, which resulted in increased travel times and passenger wait times. The main cause of service unreliability on this route was identified to be deviations at the terminals. Trips are departing the terminal with poor headway adherence (and therefore, poor on-time performance), which propagates and creates further reliability problems down the route. The causes of these terminal deviations were inferred to be a combination of poor terminal supervision and operator behavior. Recovery times, externalities and passenger loads at this terminal are inferred to cause only minor problems. At other points in the route, operator behavior and passenger loads are observed to affect reliability in the inbound direction. As for strategies to improve service reliability, emphasis is given to better supervision at the terminal. Supervisors at terminals are needed to enforce good operator behavior, balance headways, apply control strategies, and coordinate passenger loads to avoid poor departure headways and overcrowding of buses. Along the route, operator training, corrective strategies and traffic signal priority are highlighted as potential strategies to reduce the variability in running times and balance headways to reduce the occurrence of bunches and gaps in service.by Laura Cecilia Cham.S.M

The measurement of passenger preferences towards rail station and on-train facilities

This study is concerned with the provision of passenger facilities, such as catering or information, at rail stations and on trains. It takes the premise that appraisal methods vised by rail operators and planners for evaluating investment in such facilities are limited. The result can be under-investment in such facilities. It makes the case that such facilities are important devices for inproving the quality of rail travel and that under-investment in facilities implies reduced demand for rail services. It is suggested that stated preference (SP) techniques, already applied to this topic on a number of occasions, are effective methods for measuring the monetary equivalent values of passenger facilities. These values can be inserted into investment appraisal methods based on financial criteria or cost-benefit analysis. However, previous applications of SP techniques have exhibited a number of weaknesses, which have called into question the plausibility of some of the values that have been obtained. This study reports on research on the London Underground, investigating the potential introduction of a range of improvements to passenger facilities on the Northern Line. In this original work, discrete choice SP methods were used to measure the values of these improvements in a way that will produce more plausible results, it is argued, than those derived from earlier SP applications. The research showed that appreciably lower valuations were obtained with this method

Automated Transit Networks (ATN): A Review of the State of the Industry and Prospects for the Future, MTI Report 12-31

The concept of Automated Transit Networks (ATN) - in which fully automated vehicles on exclusive, grade-separated guideways provide on-demand, primarily non-stop, origin-to-destination service over an area network – has been around since the 1950s. However, only a few systems are in current operation around the world. ATN does not appear “on the radar” of urban planners, transit professionals, or policy makers when it comes to designing solutions for current transit problems in urban areas. This study explains ATN technology, setting it in the larger context of Automated Guideway Transit (AGT); looks at the current status of ATN suppliers, the status of the ATN industry, and the prospects of a U.S.-based ATN industry; summarizes and organizes proceedings from the seven Podcar City conferences that have been held since 2006; documents the U.S./Sweden Memorandum of Understanding on Sustainable Transport; discusses how ATN could expand the coverage of existing transit systems; explains the opportunities and challenges in planning and funding ATN systems and approaches for procuring ATN systems; and concludes with a summary of the existing challenges and opportunities for ATN technology. The study is intended to be an informative tool for planners, urban designers, and those involved in public policy, especially for urban transit, to provide a reference for history and background on ATN, and to use for policy development and research