Expert versus lay perception of the risks of motor vehicle-generated air pollution

We explore whether experts’ perceptions of risk differ systematically from those of the public. To do so, we examine whether experts and non-experts make different location decisions in response to ground-level ozone pollution, one of the byproducts of motorized transportation. Physicians are experts in the field of health, and thus may differ from their lay neighbors in their knowledge of and attitude toward pollution and its health risks. If so, it is possible that they value locations with cleaner air differently than their neighbors do. Here we use hedonic price models based on willingness to bear housing and commute burdens to examine the differential valuation of clean air by doctors and laypeople in the Los Angeles region between 1980 and 2000. We find no evidence that doctors are more or less more willing than comparable lay residents to trade off time or money to live in cleaner-air neighborhoods.     

Optimal distribution of financial incentives to foster off-hour deliveries in urban areas

The main objective of this paper is to develop mathematical formulations to gain insight into the best way to distribute financial incentives to receivers of urban deliveries to maximize participation in off-hour deliveries. The paper considers two different types of incentive budgets: exogenous, and endogenous. The exogenous case represents the condition in which an external decision maker determines the incentive budget that is to be distributed among potential participants in off-hour deliveries. In the case of an endogenous incentive budget, the entity distributing the incentives must raise the necessary funds using revenue generation mechanisms such as tolls and fines. The optimal incentives are obtained from the Karush–Kuhn–Tucker conditions of a mathematical program that maximizes the number of truck trips shifted to the off-hours as a function of the incentives. The mathematical models developed in this paper provide guidelines about how to optimally distribute financial incentives to foster off-hour deliveries.     

Evaluating the impact of spatio-temporal demand forecast aggregation on the operational performance of shared autonomous mobility fleets

Fleet operators rely on forecasts of future user requests to reposition empty vehicles and efficiently operate their vehicle fleets. In the context of an on-demand shared-use autonomous vehicle (AV) mobility service (SAMS), this study analyzes the trade-off that arises when selecting a spatio-temporal demand forecast aggregation level to support the operation of a SAMS fleet. In general, when short-term forecasts of user requests are intended for a finer space–time discretization, they tend to become less reliable. However, holding reliability constant, more disaggregate forecasts provide more valuable information to fleet operators. To explore this trade-off, this study presents a flexible methodological framework to evaluate and quantify the impact of spatio-temporal demand forecast aggregation on the operational efficiency of a SAMS fleet. At the core of the methodological framework is an agent-based simulation that requires a demand forecasting method and a SAMS fleet operational strategy. This study employs an offline demand forecasting method, and an online joint AV-user assignment and empty AV repositioning strategy. Using this forecasting method and fleet operational strategy, as well as Manhattan, NY taxi data, this study simulates the operations of a SAMS fleet across various spatio-temporal aggregation levels. Results indicate that as demand forecasts (and subregions) become more spatially disaggregate, fleet performance improves, in terms of user wait time and empty fleet miles. This finding comes despite demand forecast quality decreasing as subregions become more spatially disaggregate. Additionally, results indicate the SAMS fleet significantly benefits from higher quality demand forecasts, especially at more disaggregate levels.

     

Recent aspects of the EU maritime transport policy. A comment on the paper by Theo Kiriazidiz and George Tzanidakis

This paper provides a commentary on the paper by Kiriazidis and Tzanidakis which examined a very significant area of policy relating to the European Union and the Maritime sector. Whilst providing a stimulus for discussion, their paper leaves out far more from the policy framework, than it includes and as such contributes little to the broader debate.     

The Polish maritime sector under transition

This paper provides an analysis of the changes that have taken place in the Polish maritime sector between the demise of the Socialist state in 1989 and the current situation when the transformation process has had 10 years to develop. Examples are taken from the ports and shipping sectors and the conclusions provide an assessment of the structural implications of the transformation period for the overall maritime industry.     

Experimental Verification of Resistance Control, Semi-Active Damping

Electronically controlled vehicle suspensions offer substantial improvements in performance over conventional, passive suspensions but with the price of power, complexity, and actuating bandwidth. Low-bandwidth, semi-active damping addresses the problems of power and bandwidth by using low power modulation of controllable dampers at the frequency of the isolated mass. Resistance controlled, semi-active damping is experimentally verified to better sprung mass isolation while reducing suspension stroke, something that a passive system cannot do. It is also shown to compare reasonably well with computer simulation results. The experimental implementation is a 1/30 scale, two degree-of-freedom test bed that represents the standard quarter vehicle model.     

Fallow land in old docks: Why such a slow take-up of Britain's waterside redevelopment opportunities?

The recent experience of Britain's derelict port areas indicates that the process of renewal and reuse is slow and is often restricted to arbitrarily few options. Successful schemes tend to be flexible, small-scale and piecemeal, while continued dereliction is generally associated with land set aside for the ambitious large projects. The political climate for dockland renewal tends to restrict opportunities for experimentation and immediate beneficial use. However, it is unwise to see old docks as too special. They are a peculiar part of the wider process of urban land use change. Successful operation or reuse depends on good relations with this wider social and economic environment.     

Private tollroads in urban areas

Governments of all persuasions are increasingly seeking the participation of the private sector in the supply of transport facilities and services. Private sector participation in the financing, construction, operation and maintenance of infrastructure is considered a serious option in a number of countries in the search for ways of providing much needed investment which would otherwise be deferred. This paper considers some economic and financial problems in the private sector provision of major road infrastructure within urban areas. The main issues are attaching prices (i.e. tolls) to the provision of the service, the value of government rights which are being given up either permanently or temporarily, and the identification required by the promoters of the cost of capital which is essential information in establishing the risk. Broader environmental and equity issues are not addressed. If the approach to establishing a private presence in a previously public supply context is handled properly from the outset, the benefits can be significant. Contrarily however, the prospects could be quite undesirable if badly managed, despite the presence of an extended public purse.requests for offprints     

A probabilistic framework for weather-based rerouting and delay estimations within an Airspace Planning model

In this paper, we develop a novel severe weather-modeling paradigm to be applied within the context of a large-scale Airspace Planning and collaborative decision-making model in order to reroute flights with respect to a specified probability threshold of encountering severe weather, subject to collision safety, airline equity, and sector workload considerations. This approach serves as an alternative to the current practice adopted by the Federal Aviation Administration (FAA) of adjusting flight routes in accordance with the guidelines specified in the National Playbook. Our innovative contributions in this paper include (a) the concept of “Probability-Nets” and the development of discretized representations of various weather phenomena that affect aviation operations; (b) the integration of readily accessible severe weather probabilities from existing weather forecast data provided by the National Weather Service; (c) the generation of flight plans that circumvent severe weather phenomena with specified probability threshold levels, and (d) a probabilistic delay assessment methodology for evaluating planned flight routes that might encounter potentially disruptive weather along its trajectory. Additionally, we conduct an economic benefit analysis using a k-means clustering mechanism in concert with our delay assessment methodology in order to evaluate delay costs and system disruptions associated with variations in probability-net refinement-based information. Computational results and insights are presented based on flight test cases derived from the Enhanced Traffic Management System data provided by the FAA and using weather scenarios derived from the Model Output Statistics forecast data provided by the National Weather Service.     

Metadata-based Needs Assessment for Emergency Transportation Operations with a Focus on an Aging Population: A Case Study in Florida

In the aftermath of disasters, evacuating aging victims and maintaining an optimal flow of critical resources in order to serve their needs becomes problematic, especially for Gulf Coast states in the USA such as Florida, where more than 6.9 million (36.9%) of the population are over age 50. Scanning the literature, there is no substantial prior work that has synthesized the requirements for a multi-modal emergency needs assessment that could facilitate the safe and accessible evacuation of aging people, and optimize the flow of resources into the affected region to satisfy the needs of those who remain. This paper presents a review of the aging population-focused emergency literature utilizing a knowledge base development methodology supported with a geographic information system-based case study application set in Florida. Importance is given to both ensuring the resiliency of the transportation infrastructure and meeting the needs of aging populations. As a result of this metadata-based analysis, critical research needs and challenges are presented with planning recommendations and future research directions. Results clearly indicate that transportation agencies should focus on clear and fast dissemination of disaster-related information to the aging populations. The use of paratransit services for evacuating aging people, especially those living independently and/or in rural areas, is also found to be of paramount importance.