Using stated preference survey data, we measure the value of travel time for several transport modes. We find, like many before us, that the value of travel time varies across modes in the opposite direction of what would be the consequence of differences in comfort. We examine three candidate causes for the observed differences: Comfort effects, self-selection and strategic behaviour of respondents. Using experiments with both the current and an alternative mode we find that the differences in the value of travel time are consistent with self-selection and comfort effects. Moreover, respondents having bus as the current or the alternative mode seem not to value comfort differently across modes. Strategic behaviour seems to play no role. 相似文献
Long-term variability of the biogeochemical properties during the formation of central waters in the Eastern North Atlantic were analyzed between 42–47°N and 10–20°W from the dataset gathered during the Galicia VII (GVII) and C. Darwin 58/59 (CD58/59) cruises. These cruises that showed important changes in the thermohaline properties and the nutrient abundance of the upper layers were carried out under contrasting conditions of the North Atlantic Oscillation (NAO) index. The different climate forcing led a meridional shift of the transition zone between the formation regions of subpolar and subtropical Eastern North Atlantic Central Water (ENACWp and ENACWt, respectively). This displacement conditioned the presence of each ENACW in the study region and so the thermohaline and biogeochemical properties. The effect of the observed variability at decadal scale on the air–sea CO2 gradient (ΔfCO2) and exchange (FCO2) was analyzed using 1D model approach throughout 11 weekly-steps that simulated the development of a spring bloom during the shoaling of the mixed layer. The outputs of the model showed an intensification of the ocean CO2 uptake due to higher biological CO2 drawdown, during positive NAO conditions and its weakening under negative NAO influence. 相似文献
Residence times and exposure times are computed for 13 boxes in the Scheldt Estuary, using the high-resolution tracer-transport model SLIM. The concepts are clearly defined and related to how they should be computed. First, the timescale values are compared with results published previously that were obtained with a simple box model, and an unexpected difference is revealed. This may suggest that a high-resolution model is necessary, even for the computation of such integrated quantities as residence or exposure times. Secondly, the newly computed residence times are compared to the exposures times to illustrate their intrinsic differences. From this difference, it is possible to propose a return coefficient, expressing the fraction of the exposure time that is due to “returning water”, i.e. water which has already left the estuary at least once. Finally, the estuarine exposure times are decomposed into the different box exposure times, resulting in a connectivity matrix. This matrix expresses how much time is spent in each of the estuarine subdomains during the water parcels' journey through the estuary. 相似文献
This paper develops a comprehensive approach to the definition of transportation analysis zones (TAZ), and therein, presents
a new methodology and algorithm for the definition of TAZ embedded in geographic information systems software, improves the
base algorithm with several local algorithms, and comprehensively analyses the obtained results. The results obtained are
then compared to these presently used in the transportation analysis process of the Lisbon Metropolitan Area. The proposed
algorithm presents a new methodology for TAZ design based on a smoothed density surface of geocoded travel demand data. The
algorithm aims to minimise the loss of information when moving from a continuous representation of the origin and destination
of each trip to their discrete representations through zones, and focuses on the trade-off between the statistical precision,
geographical error, and the percentage of intra-zonal trips of the resulting OD matrix. The results for the Lisbon Metropolitan
Area case study suggest a significant improvement in OD matrix estimates compared to current transportation analysis practises
based on administrative units.
Elisabete A. SilvaEmail:
Luis M. Martínez
is a Civil Engineer from the Instituto Superior Técnico, Technical University of Lisbon since 2004. After finishing his degree,
he started his work as researcher in the CESUR (Civil Engineering & Architecture Department—Instituto Superior Técnico) where
he has been working since. In 2006 he completed his Master Thesis at Instituto Superior Técnico on Traffic Analysis Zones
modeling and started his PhD studies on the theme: Metropolitan Transportation Systems Financing Using the Value Capture Concept.
José Manuel Viegas
is Full Professor of Transportation at the Civil Engineering & Architecture Department of the Instituto Superior Técnico,
Technical University of Lisbon. He has worked extensively in Modeling, Innovation and Policy in several types of Transport
Systems. He was founder and first Director General of Transportnet, a group of eight leading European Universities with Advanced
Studies in Transportation, and currently leads the Portuguese side of the Transportation Systems area in the MIT—Portugal
program.
Elisabete A. Silva
is at the University of Cambridge (University Lecturer in Planning at the Department of Land Economy and a Fellow of Robinson
College). With more than 100 contributions in peer review journals, books/books chapters, conference proceedings, and a research
track record of approximately 16 years, (both at the public and private sector), her research interests are centred on the
application of new technologies to spatial planning in particular city and metropolitan dynamic modelling through time. 相似文献
Transportation - Historically cities are formed to provide interaction and communication opportunities for communities. As cities become smarter, new forms of interactions are formed and the... 相似文献
Transportation - Developing economies are still in the stage of e-commerce deployment, unlike in developed countries, where online shopping is already a common purchase channel. This research aims... 相似文献
The ubiquity of personal cellular phones in society has led to a surging interest in using Big Data generated by mobile phones in transport research. Studies have suggested that the vast amount of data could be used to estimate origin–destination (OD) matrices, thereby potentially replacing traditional data sources such as travel surveys. However, constructing OD matrices from mobile phone data (MPD) entails multiple challenges, and the lack of ground truth hampers the evaluation and validation of the estimated matrices. Furthermore, national laws may prohibit the distribution of MPD for research purposes, compelling researchers to work with pre-compiled OD matrices with no insight into the methods used. In this paper, we analyse a set of such pre-compiled OD matrices from the greater Oslo area and perform validation procedures against several sources to assess the quality and robustness of the OD matrices as well as their usefulness in transportation planning applications. We find that while the OD matrices correlate well with other sources at a low resolution, the reliability decreases when a finer level of detail is chosen, particularly when comparing shorter trips between neighbouring areas. Our results suggest that coarseness of data and privacy concerns restrict the usefulness of MPD in transport research in the case where OD matrices are pre-compiled by the operator.
ABSTRACTTo date, relatively little is known about the nature of the demand for high-speed rail (HSR) soon after inauguration of the services, despite close to 50-year experience of HSR operation and 17 166?km of HSR network around the world. This is a real lacuna given the scale of HSR construction around the world, the amount of resources committed to it, the desired accessibility, economic and environmental effects associated with HSR development and the relatively poor track record of forecasting demand for HSR services. Focusing on mode substitution and induced demand effects, this review aims to fill the gap in knowledge about the ex-post demand for HSR services in order to facilitate a learning process for the planning of the future HSR network. Although there is not much evidence on the demand for HSR services and existing evidence is largely influenced by route-specific characteristics, a methodological limitation that must be acknowledged, the evidence presented allows a better characterisation of HSR as a mode of transport. The review shows that the demand for HSR a few years after inauguration is about 10–20% induced demand and the rest is attributed to mode substitution. In terms of mode substitution, in most cases the majority of HSR passengers have used the conventional rail before. Substitution from aircraft, car and coach is generally more modest. 相似文献
Abstract The increasing capacity of technological tools, as well as the advent of geographic information systems, has multiplied the ability to process large sets of microdata. At the same time, modeling concerns and the quest for a more in-depth understanding of individual behaviors is requiring more, and better, data. The gap between scientific modeling and informational tools for decision-making seems to be widening. In the Greater Montreal area, large sets of microdata have been available for more than 30 years. Along with the development of modeling and planning tools, particular attention has been given to the continuous enlightening of planners and decision-makers with respect to the outcomes of the various surveys. This has led to the development of particular interactive tools, specifically addressed at local planners, which present the most significant information regarding travel and demography, for geopolitically relevant areas. This paper presents the most recent interactive tool that has been developed for local planners in the Montreal area. It integrates information from both the most recent travel survey held in the region and the Canadian census. It offers both ease of use and relevant analytical means to assist in exploring the complex relations between spatial locations, demographic features, and activity-travel indicators. 相似文献