The quality of survey data: Telephone versus face-to-face interviews

Those designing surveys and producing data have always been concerned about its quality. The increasing stringency of the financial constraints which affect public authorities and the increased scope of involvement in the regulation of urban travel has led us to pay even greater attention to the quality of data. This issue is frequently covered in the literature on survey methods. However, comparisons between different survey methods are more rarely conducted. The decision to conduct such an analysis is partly the result of the development of telephone use to the detriment of other survey modes in many countries and also the development of Computer-Aided Telephone Interviewing (CATI) which facilitates the running and monitoring of the survey.This paper examines several aspects of this question in order to compare the performance of telephone and face-to-face interviews. The first aspect is the representativeness of the sample, and therefore relates mainly to the issue of nonresponses and the choice of a sample base. The second concerns the accuracy of the information and involves the choice of a survey area and the recording of all trips, including short-distance travel. Finally, the quality of data is obviously determined by the quality of the responses given by those interviewed.The answers we give frequently depend on the objective of the surveys, which leads us to put forward a table which summarizes the performance of telephone and face-to-face interviews on the basis of the main objective of the survey. Broadly, the telephone seems to be the favoured tool for surveys in the area of transport planning and surveys which aim to provide data for forecasting models, mostly on the grounds of cost. However, face-to-face techniques are often preferred for surveys which aim to discover and analyze the factors which explain individual travel behaviour.     

3D brush model to predict longitudinal tyre characteristics

A 3D tyre brush model, which aims to predict the longitudinal tyre characteristic under steady-state conditions by modelling the occurring physical effects in the tyre–road contact patch, is presented. The model includes an analytical method to describe the tyre footprint geometry, the pressure distribution, the slip due to the lateral tyre contour, the slip due to braking or traction and the longitudinal as well as the lateral shear stresses on a flattened tyre. The presented development tool offers a method to investigate different rubber friction data (caused by different tread compounds and/or surface textures) and to analyse its influence on longitudinal tyre characteristics. The tyre design is fixed (same casing, dimension and pattern). The results include the shear stresses as well as the different sliding velocities in the contact patch for different slip conditions. The model was developed for a standard summer pattern design and a standard tyre dimension (205/55R16). It can also be adapted to other tread designs and tyre dimensions. To offer a good comparability between model results and test bench measurements, the surface curvature of an internal test rig is considered.     

Strategies to achieve deep reductions in metropolitan transportation GHG emissions: the case of Philadelphia

ABSTRACT

This paper investigates strategies that could achieve an 80% reduction in transportation emissions from current levels by 2050 in the City of Philadelphia. The baseline daily lifecycle emissions generated by road transportation in the Greater Philadelphia Region in 2012 were quantified using trip information from the 2012 Household Travel Survey (HTS). Emissions were projected to the year 2050 accounting for population growth and trends in vehicle technology for both the Greater Philadelphia Region and the City of Philadelphia. The impacts of vehicle technology and shifts in travel modes on greenhouse gas (GHG) emissions in 2050 were quantified using a scenario approach. The analysis of 12 different scenarios suggests that 80% reduction in emissions is technically feasible through a combination of active transportation, cleaner fuels for public transit vehicles, and a significant market penetration of battery-electric vehicles. The additional electricity demand associated with greater use of electric vehicles could amount to 10.8 TWh/year. The use of plug-in hybrid electric vehicles (PHEV) shows promising results due to high reductions in GHG emissions at a potentially manageable cost.     

The impact of ignoring intrazonal trips in assignment models: a stochastic approach

Transportation - In transportation modeling, intrazonal trips are frequently omitted during trip assignment. These trips are not assigned to the network because their origin and destination are in...     

Book Reviews

The ever-changing environment in which ports operate has put strong pressure on the traditional role of public port authorities. Market developments have created the need for ports to be part of wider logistics networks and to provide value-added services. Powerful private players who are organised on a global scale, such as carriers, terminal operators and logistics service providers, struggle to gain control over port-oriented logistics networks whereas port authorities very often seem to remain local spectators with limited influence on these market-driven processes. Port authorities are on the other hand, the focal point of criticism from societal interests such as local government, NGOs and citizens for negative externalities related to port development and port operations even if these do not always fall within their direct responsibility. In 1990, Richard Goss questioned, albeit rather rhetorically, the need to have public sector port authorities. Since then scholars have demonstrated a true renaissance or renewed interest in the role of port authorities, recommending repositioning and development of new strategies. Parallel to the concept of the ‘renaissance man’, which is defined as a person who is well educated and excels in a wide variety of subjects or fields, a kind of ‘renaissance port authority’ is emerging from literature which may take on a variety of facilitating and even entrepreneurial tasks. The purpose of this article is to develop a conceptual framework for the various options at hand, based on an extensive literature review of port authority functions. The framework also identifies the principal governance-related factors that may in practice enable or prevent port authorities, particularly in Europe, from assuming the renaissance ambitions advocated by scholars. The hypotheses developed in this article form the basis of a wider empirical research agenda into reform of port governance in Europe and elsewhere in the world.     

Transport reviews prize

The transport problems that urban centres now face (as regard congestion, the environment and public deficits) have led to an examination of competition in the sector. Some countries have moved towards the deregulation or privatization of urban public transport, influenced by developments in the theory of contestable markets. These analyses could potentially provide a means of increasing the efficiency of public services and, hence, public transport. However, the authors do not feel that they can deal with the full extent of the problem. Particularly in urban areas, there is a need nowadays to examine the issue of competition between the passenger car and public transport, especially from the pricing angle. In France, decades of policy strongly influenced by a preference for the car have prevented this problem from being a central concern for researchers and decision-makers. The approach to the problem has mainly been centred on increasing urban supply to meet demand better. However, a failure to consider pricing, and the subsidization phenomena that can occur as a result, affects the shape of supply systems. Pricing, through its action on demand, acts on supply by increasing or reducing its potential profitability. 'Snowball' effects can, therefore, mean that slight underpricing results in the domination of one transport mode. These effects have been revealed in particular by work in the new field of network economics. The example of the Lyon conurbation shall be used to illustrate the case, which is that car travel is underpriced. The basis of the exposé will be a detailed analysis of the externalities associated with the car, i.e. the costs of car use and the revenue it raises for the community. The second part of the paper is a study of several urban travel policies in Europe (France, UK, Switzerland, Italy) to show the 'effects' of this underpricing. Where supply has followed the pressure of demand, the dominance of the car has been reinforced. However, in cities, particularly in Switzerland, where supply has been restricted, this dominance has been considerably moderated. On the other hand, it can be seen from the French example that taking strong action to improve public transport is not in itself sufficient to increase usage. Several lessons can be learnt from this work. First, it is shown, if it was still necessary to do so, that the problems of urban travel require a comprehensive and coherent approach. Modal policy must, therefore, be assessed with reference to the entire transport system. Next, in connection with the issue of regulation, it is important to consider the issue of competition in urban areas, and not only competition between public transport operators, but also (and even above all) competition within the entire system of personal and public transport. Finally, with regard to pricing, the ratchet effects that benefit the car as a result of its underpricing in urban areas need to be studied.     

Discussing the “positive utilities” of autonomous vehicles: will travellers really use their time productively?

ABSTRACT

Autonomous vehicles (AVs) are expected to reshape travel behaviour and demand in part by enabling productive uses of travel time—a primary component of the “positive utility of travel” concept—thus reducing subjective values of travel time savings (VOT). Many studies from industry and academia have assumed significant increases in travel time use and reductions in VOT for AVs. In this position paper, I argue that AVs’ VOT impacts may be more modest than anticipated and derive from a different source. Vehicle designs and operations may limit activity engagement during travel, with AV users feeling more like car passengers than train riders. Furthermore, shared AVs may attenuate travel time use benefits, and productivity gains could be limited to long-distance trips. Although AV riders will likely have greater activity participation during travel, many in-vehicle activities today may be more about coping with commuting burdens than productively using travel time. Instead, VOT reductions may be more likely to arise from a different “positive utility”—subjective well-being improvements through reduced stresses of driving or the ability to relax and mentally transition. Given high uncertainty, further empirical research on the experiential, time use, and VOT impacts of AVs is needed.     

Coastal and Ocean Management in Canada: Moving into the 21st Century

The experience in coastal management in the tropics that is presented in this special issue is considered in light of other coastal management initiatives worldwide. The major challenges confronting those working to promote cross-sectoral, participatory approaches to the management of coastal areas are discussed. Emerging conceptual frameworks are considered. Several factors critical to the design of coastal management projects and programs are identified. The article concludes with a reflection on priorities for furthering the practice of coastal management in the next decade.