Developments in transit fare policy reform

Transit providers around the world are progressively migrating from automatic fare collection systems to state-of-the-art contactless smartcard systems. The introduction of this new technology provides a unique opportunity for transit agencies to review fares and ticketing policy and leverage the full functionality of these new ticketing systems. Research being undertaken at the University of Queensland seeks to develop recommendations on potential fares and ticketing policy reform using contactless smartcard technologies. Recent experience indicates that introduction of many of the new ticketing systems have been technology- rather than policy-driven. The fare structure is basically a relationship between fare levels and distance travelled, including flat, distance based, time-based and zonal fare structures. Transit fares policy results from trade-offs between competing objectives, such as economic, social or political, but examples of actual policies are extremely hard to find. The availability of new smartcard technology provides the opportunity to provide a 'closed' fare collection system, without physical barriers, allowing more differentiated fare structures based on distance travelled. In addition, there are significant opportunities for integrated ticketing and product innovation

Generalized Galileons: All scalar models whose curved background extensions maintain second-order field equations and stress tensors

We extend to curved backgrounds all flat-space scalar field models that obey purely second-order equations, while maintaining their second-order dependence on both field and metric. This extension simultaneously restores to second order the, originally higher derivative, stress tensors as well. The process is transparent and uniform for all dimensions

Rail transit fare collection: Policy and technology assessment

The impact of fare policies and fare structure on the selection of equipment was investigated, fare collection systems are described, hardware and technology related problems are documented, and the requirements of a fare collection simulation model are outlined. Major findings include: (1) a wide variation in the fare collection systems and equipment, caused primarily by historical precedence; (2) the reliability of AFC equipment used at BART and WMATA discouraged other properties from considering use of similar equipment; (3) existing equipment may not meet the fare collection needs of properties in the near future; (4) the cost of fare collection operation and maintenance is high; and (5) the relatively small market in fare collection equipment discourages new product development by suppliers. Recommendations for fare collection R&D programs include development of new hardware to meet rail transit needs, study of impacts of alternate fare policies increased communication among policymakers, and consensus on fare policy issues

Bus rapid transit

Effective public transit is central to development. For the vast majority of developing city residents, public transit is the only practical means to access employment, education, and public services, especially when such services are beyond the viable distance of walking or cycling. Unfortunately, the current state of public transit services in developing cities often does little to serve the actual mobility needs of the population. Bus services are too often unreliable, inconvenient and dangerous. In response, transport planners and public officials have sometimes turned to extremely costly mass transit alternatives such as rail-based metros. Due to the high costs of rail infrastructure, cities can only construct such systems over a few kilometres in a few limited corridors. The result is a system that does not meet the broader transport needs of the population. Nevertheless, the municipality ends up with a long-term debt that can affect investment in more pressing areas such as health, education, water, and sanitation. However, there is an alternative between poor public transit service and high municipal debt. Bus Rapid Transit (BRT) can provide high-quality, metro-like transit service at a fraction of the cost of other options. This document provides municipal officials, non-governmental organizations, consultants, and others with an introduction to the concept of BRT as well as a step-by-step process for successfully planning a BRT system

Tests of scalar-tensor gravity

The best motivated alternatives to general relativity are scalar-tensor theories, in which the gravitational interaction is mediated by one or several scalar fields together with the usual graviton. The analysis of their various experimental constraints allows us to understand better which features of the models have actually been tested, and to suggest new observations able to discriminate between them. This talk reviews three classes of constraints on such theories, which are qualitatively different from each other: (i) solar-system experiments; (ii) binary-pulsar tests and future detections of gravitational waves from inspiralling binaries; (iii) cosmological observations. While classes (i) and (ii) impose precise bounds respectively on the first and second derivatives of the matter-scalar coupling function, (iii) a priori allows us to reconstruct the full shapes of the functions of the scalar field defining the theory, but obviously with more uncertainties and/or more theoretical hypotheses needed. Simple arguments such as the absence of ghosts (to guarantee the stability of the field theory) nevertheless suffice to rule out a wide class of scalar-tensor models. Some of them can be probed only if one takes simultaneously into account solar-system and cosmological observations.Comment: 18 pages, 6 figures, invited talk at the workshop "Phi in the Sky: The Quest for Cosmological Scalar Fields", Porto, 8-10 July 200

Dark Matter via Massive (bi-)Gravity

In this work we investigate the existence of relativistic models for dark matter in the context of bimetric gravity, used here to reproduce the modified Newtonian dynamics (MOND) at galactic scales. For this purpose we consider two different species of dark matter particles that separately couple to the two metrics of bigravity. These two sectors are linked together \textit{via} an internal $U(1)$ vector field, and some effective composite metric built out of the two metrics. Among possible models only certain classes of kinetic and interaction terms are allowed without invoking ghost degrees of freedom. Along these lines we explore the number of allowed kinetic terms in the theory and point out the presence of ghosts in a previous model. Finally, we propose a promising class of ghost-free candidate theories that could provide the MOND phenomenology at galactic scales while reproducing the standard cold dark matter (CDM) model at cosmological scales.Comment: 7 pages, references added, typos corrected, journal versio

Improving relativistic MOND with Galileon k-mouflage

We propose a simple field theory reproducing the MOND phenomenology at galaxy scale, while predicting negligible deviations from general relativity at small scales thanks to an extended Vainshtein ("k-mouflage") mechanism induced by a covariant Galileon-type Lagrangian. The model passes solar-system tests at the post-Newtonian order, including those of local Lorentz invariance, and its anomalous forces in binary-pulsar systems are orders of magnitude smaller than the tightest experimental constraints. The large-distance behavior is obtained as in Bekenstein's tensor-vector-scalar (TeVeS) model, but with several simplifications. In particular, no fine-tuned function is needed to interpolate between the MOND and Newtonian regimes, and no dynamics needs to be defined for the vector field because preferred-frame effects are negligible at small distances. The field equations depend on second (and lower) derivatives, and avoid thus the generic instabilities related to higher derivatives. Their perturbative solution around a Schwarzschild background is remarkably simple to derive. We also underline why the proposed model is particularly efficient within the class of covariant Galileons.Comment: 6 pages, 1 figure, RevTeX4 forma