Linking an activity-based travel demand model with traffic emission and dispersion models: Transport’s contribution to air pollution in Toronto

This paper describes the development of an integrated approach for assessing ambient air quality and population exposure as a result of road passenger transportation in large urban areas. A microsimulation activity-based travel demand model for the Greater Toronto Area – the Travel Activity Scheduler for Household Agents – is extended with capabilities for modelling and mapping of traffic emissions and atmospheric dispersion. Hourly link-based emissions and zone-based soak emissions were estimated. In addition, hourly roadway emissions were dispersed at a high spatial resolution and the resulting ambient air concentrations were linked with individual time-activity patterns derived from the model to assess person-level daily exposure. The method results in an explicit representation of the temporal and spatial variation in emissions, ambient air quality, and population exposure.     

Guidelines for samplers: measuring a change in behaviour from before and after surveys

This paper addresses the issue of using before and after surveys to evaluate behavioural changes in response to transport policies and investments, a procedure that, we argue is done far too rarely in this profession. Further, it demonstrates very clearly that, in almost all conceivable cases, there are considerable economies to be obtained by using a panel (again, under-utilised in our profession) to undertake evaluation, rather than successive independent cross-sectional surveys. The paper also addresses the critical issue of sample size requirements for measuring changes of a relatively small magnitude in travel behaviour; i.e., to state, with 95% confidence, that if there is a ∂ percent change in behaviour for the sample, there is a ∂ percent ± e percent change in the behaviour of the population, where e is the sampling error. In this paper, we present a method for calculating such sample size requirements from first principles and demonstrate the applicability both hypothetically and then empirically using data from the Puget Sound Transportation Panel. The formulation enables designers of before and after surveys to investigate the trade-offs between the statistical accuracy of their predictions and the sample size requirements systematically, without the need to specify ∂ a priori. This latter point is crucial, we argue, because we have limited information on ∂, yet, as we explain here, it drives the sample size requirements using alternative, well-cited approaches for calculating sample sizes to assess behavioural change. The results have important ramifications both for those implementing transport policies intended to produce behavioural change, especially when a cost-benefit evaluation of the policy is desired, and for those interpreting the results reported in previous studies.     

An inverse model for calculation of global volume transport from wind and hydrographic data

The P-vector inverse method has been successfully used to invert the absolute velocity from hydrographic data for the extra-equatorial hemispheres, but not for the equatorial region since it is based on the geostrophic balance. A smooth interpolation scheme across the equator is developed in this study to bring together the two already known solutions (P-vectors) for the extra-equatorial hemispheres. This model contains four major components: (a) the P-vector inverse model to obtain the solutions for the two extra-equatorial hemispheres, (b) the objective method to determine the Ψ-values at individual islands, (c) the Poisson equation-solver to obtain the Π-values over the equatorial region from the volume transport vorticity equation, and (d) the Poisson equation-solver to obtain the Ψ and depth-integrated velocity field (U, V) over the globe from the Poisson Ψ-equation. The Poisson equation-solver is similar to the box model developed by Wunsch. Thus, this method combines the strength from both box and P-vector models. The calculated depth-integrated velocity and Ψ-field agree well with earlier studies.     

Control of traffic in residential neighborhoods: Some considerations for implementation

The effect of motor vehicles upon older neighborhoods has received increasing attention as residents of these areas seek to preserve the quality of life in their neighborhoods. In order to reduce through traffic in residential neighborhoods, numerous techniques have been developed, ranging from turn prohibitions to physical barriers. Since these measures have negative impacts on previous users of the streets, there has been substantial opposition to them. This paper reviews the major areas of conflict as revealed through court challenges.Nine court cases were identified by the researchers. In four, the court decision supported the control measures; in five, the courts decided against the actions. Six of the nine cases are reviewed in this paper. Major legal issues which are identified include the appropriate use of municipal police power, reasonableness in the exercise of police power, the integration of control measures into an overall transportation plan, appropriate consideration of emergency vehicle needs and the rights of access to property, and public participation in the decision. The authors conclude that properly planned and executed diversion strategies can be implemented and can withstand challenges by negatively affected parties.The opinions, findings, and conclusions expressed or implied in this paper are those of the authors only. They are not necessarily those of the Federal Highway Administration.     

Locating and sizing park-ride lots with interactive computer graphs

Two alternative methods for conducting a preliminary analysis of the problem of locating and sizing park-ride lots for an urban bus transit system are examined. These alternative methods are tested using a large and complex street network representing the northern half of the City of Seattle, Washington. Four design criteria are identified and an overall measure of system performance is devised. The problem is to determine the size and location of three park-ride lots that will maximize the performance of the system. The first method utilizes a computing system called LOCATOR II in an interactive graphic mode. In an experimental setting, five students use LOCATOR II to locate three park-ride lots and their solutions are found to exhibit a very high average level of performance. The second method does not involve a direct interaction with the computing system but does use LOCATOR II in a batch mode. Several students participate in three rounds of the batch mode experiment and the performance of their designs is somewhat poorer than the designs found in the interactive graphics experiment. Overall, the experimental results show that relatively inexperienced persons can find a high performance design for a reasonably complex problem quickly and inexpensively. These designs can provide a good starting point for the detailed consideration of many of the other aspects of the problem of providing a high performance bus transit service in an urban area.     

The application of cost-benefit analysis to transport investment projects in Britain

This paper explains the need for the application of cost-benefit analysis to the evaluation of alternative projects for investment in the transport field and outlines briefly the historical development of the technique. The results of a comparative survey of a number of cost-benefit studies which have been carried out in Britain and some conclusions as to their thoroughness and comprehensiveness (or otherwise) are presented. The article concludes with a number of specific and detailed recommendations to remedy apparent methodological weaknesses. Six of these recommendations seem to merit particular attention:

1. The viewpoint of most studies should be extended so as to avoid confinement, for example, within an arbitrary local government boundary, and a wider range of “externalities” should be considered. Intangibles should be included explicitly in all such evaluation exercises.
2. The actual incidence of costs and benefits should be examined in order to indicate the directional impact of the project and its implications in terms of equity. The elimination of transfer payments and double-counting should be postponed until the latest possible stage in the evaluation.
3. Equity considerations should be investigated in any transportation plan, since most projects have considerable equity implications for particular areas or socio-economic groups.
4. Discounted cash flow techniques, which are still used only in a minority of transportation studies, should become standard practice. Most evaluations are based on a single-year rate of return, or at best on simple trend forecasting. More resources should be devoted to proper evaluation of alternative plans which give due importance to the cost and benefit streams through time.
5. Sensitivity analysis should be used in all transportation evaluations. Knowledge of the impact of different assignments, shadow prices, and discount rates are essential information for any decisionmaker.
6. Last, but not least, much greater communication should exist between analyst and decisionmaker than has existed in the past.

     

Are we there yet? Assessing smartphone apps as full-fledged tools for activity-travel surveys

Transportation - Given the limitations of traditional methods of data collection and the increased use of smartphones, there is growing attention given to using smartphone apps for activity-travel...     

Reliable route guidance: A case study from Chicago

Reliable route guidance can be obtained by solving the reliable a priori shortest path problem, which finds paths that maximize the probability of arriving on time. The goal of this paper is to demonstrate the benefits and applicability of such route guidance using a case study. An adaptive discretization scheme is first proposed to improve the efficiency in computing convolution, a time-consuming step used in the reliable routing algorithm to obtain path travel time distributions. Methods to construct link travel time distributions from real data in the case study are then discussed. Particularly, the travel time distributions on arterial streets are estimated from linear regression models calibrated from expressway data. Numerical experiments demonstrate that optimal paths are substantially affected by the reliability requirement in rush hours, and that reliable route guidance could generate up to 5-15% of travel time savings. The study also verifies that existing algorithms can solve large-scale problems within a reasonable amount of time.     

铁路私有化席卷非洲大陆

非洲铁路实施特许权转让已经有10多年的历史。加拿大CPCS Transcom公司曾帮助非洲9个国家铁实施了路私有化改造。今天的经验来自历史的教训。