Shuttle Planning for Link Closures in Urban Public Transport Networks

Urban public transport systems must periodically close certain links for maintenance, which can have significant effects on the service provided to passengers. In practice, the effects of closures are mitigated by replacing the closed links with a simple shuttle service. However, alternative shuttle services could reduce inconvenience at a lower operating cost. This paper proposes a model to select shuttle lines and frequencies under budget constraints. We propose a new formulation that allows a minimal frequency restriction on any line that is operated and minimizes passenger inconvenience cost, which includes transfers and frequency-dependent waiting time costs. This model is applied to a shuttle design problem based on a real-world case study of the Massachusetts Bay Transportation Authority network of Boston, Massachusetts. The results show that additional shuttle routes can reduce passenger delay compared to the standard industry practice, while also distributing delay more equally over passengers, at the same operating budget. The results are robust under different assumptions about passenger route choice behavior. Computational experiments show that the proposed formulation, coupled with a preprocessing step, can be solved faster than prior formulations

Disruption Management in Passenger Railway Transportation

This paper deals with disruption management in passenger railway transportation. In the disruption management process, many actors belonging to different organizations play a role. In this paper we therefore describe the process itself and the roles of the different actors. Furthermore, we discuss the three main subproblems in railway disruption management: timetable adjustment, and rolling stock and crew re-scheduling. Next to a general description of these problems, we give an overview of the existing literature and we present some details of the specific situations at DSB S-tog and NS. These are the railway operators in the suburban area of Copenhagen, Denmark, and on the main railway lines in the Netherlands, respectively. Since not much research has been carried out yet on Operations Research models for disruption management in the railway context, models and techniques that have been developed for related problems in the airline world are discussed as well. Finally, we address the integration of the re-scheduling processes of the timetable, and the resources rolling stock and crew

Deduction of passengers' route choice from smart card data

Deducing passengers' route choice from smart card data provides public transport operators the opportunity to evaluate passenger service. Especially in case of disruptions when route choice models may not be valid this is an advantage. This paper proposes a method for deducing the chosen route of passengers based on smart card data and validates this method on a real life data set. The method reaches an accuracy of about 90 percent, also in case of disruptions. Moreover, it is shown how this method can be used to evaluate passenger service by a case study based on a real life data set of Netherlands Railways, the largest passenger railway operator of the Netherlands

Model Reuse with Metamodel-Based Transformations

Abstract. Metamodel-based transformations permit descriptions of mappings between models created using different concepts from possibly overlapping domains. This paper describes the basic algorithms used in matching metamodel constructs, and how this match is to be applied. The transformation process facilitates the reuse of models specified in one domain-specific modeling language in another context: another domain-specific modeling language. UML class diagrams are used as the language of the metamodels. The focus of the paper is on the matching and firing of transformation rules, and on finding efficient and generic algorithms. An illustrative case study is provided.

On Metamodel Composition

Abstract-- Computer-based systems (CBS) development integrates various disciplines, such as hardware design, software engineering, and performance modeling, as well as the “base ” engineering discipline in which the CBS will operate. As such, use of a “non-native ” modeling language is not acceptable when performing CBS design, and rapid specification and development of domain-specific modeling languages (DSMLs) is necessary. We advocate a UML-based metamodeling technique to DSML specification and generation. A key feature of our approach is the composition of new metamodels from existing metamodels through the use of three newly defined UML operators—equivalence, implementation inheritance, and interface inheritance. This paper describes the development of these new operators, details how they are used in metamodel composition, and presents examples of metamodel composition. Index terms--metamodeling, model composition, model-based computing, UML I

Protein/Lipid Interaction in the Bacterial Photosynthetic Reaction Center: Phosphatidylcholine and Phosphatidylglycerol Modify the Free Energy Levels of the Quinones

The role of characteristic phospholipids of native membranes, phosphatidylcholine (PC), phosphatidylglycerol (PG), and cardiolipin (CL), was studied in the energetics of the acceptor quinone side in photosynthetic reaction centers of Rhodobacter sphaeroides. The rates of the first, k AB(1), and the second, kAB(2), electron transfer and that of the charge recombination, kBP, the free energy levels of Q A-QB and QAQB- states, and the changes of charge compensating protein relaxation were determined in RCs incorporated into artificial lipid bilayer membranes. In RCs embedded in the PC vesicle, kAB(1) and kAB(2) increased (from 3100 to 4100 s-1 and from 740 to 3300 s-1, respectively) and kBP decreased (from 0.77 to 0.39 s-1) compared to those measured in detergent at pH 7. In PG, kAB(1) and kBP decreased (to values of 710 and 0.26 s-1, respectively), while kAB(2) increased to 1506 s-1 at pH 7. The free energy between the QA-QB and Q AQB- states decreased in PC and PG (ΔG°QA-QB→QAQ B- = -76.9 and -88.5 meV, respectively) compared to that measured in detergent (-61.8 meV). The changes of the QA/Q A- redox potential measured by delayed luminescence showed (1) a differential effect of lipids whether RC incorporated in micelles or vesicles, (2) an altered binding interaction between anionic lipids and RC, (3) a direct influence of PC and PG on the free energy levels of the primary and secondary quinones probably through the intraprotein hydrogen-bonding network, and (4) a larger increase of the QA/QA- free energy in PG than in PC both in detergent micelles and in single-component vesicles. On the basis of recent structural data, implications of the binding properties of phospholipids to RC and possible interactions between lipids and electron transfer components will be discussed