Does the accessibility measure influence the results of residential location choice modelling?

Transportation - Accessibility is essential in land-use transport interaction frameworks. For residential location choices in particular, it has always been important at the theoretical level. At...     

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.     

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...     

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.     

Combining web and face-to-face in travel surveys: comparability challenges?

Response rates for household travel surveys are tending to fall, and it seems unlikely that this trend will be reversed in the future. In recent years, travel data collection methods have evolved in order to obtain reliable data that are sufficiently detailed to feed increasingly complex models, and in order to integrate new technologies into survey protocols (Internet, GPS??). Combining different media is an obvious low-cost way of improving data quality as it increases the overall response rate. But the question of the comparability of data over time and between different survey modes remains unresolved. This paper makes a comparative analysis between the travel behaviours of web-based survey respondents and respondents to a face-to-face interview. The data were obtained from the 2006 Lyon conurbation household travel survey. Our analysis shows that the Internet respondents reported fewer trips per day than the face-to-face respondents (3.00 vs. 4.04 daily trips), and that the differences between the two groups varied according to the travel mode and trip purpose. While part of this difference can be explained by socioeconomic disparities (the Internet respondents had a specific profile) we cannot exclude the possibility of under-reporting due to the web medium.     

An application of activity-based travel analysis to simulation of change in behaviour

People are liable to exaggerate their future use of new transport facilities when they are interviewed about it before it is in operation. This is often due to the fact that they have no real frame of reference for the study. In order to overcome this, we have tried to perfect an original behaviour-change simulation method (Section 1). It has been tested on a town on the outskirts of Lyons (France) and has provided interesting results. However, to use it as a forecasting tool, we have to make sure that the assertions by potential users when interviewed are consistent with actual behaviour when the new facilities become available (Section 2). This test was carried out when a new light rail line was introduced in Grenoble (France). A first survey was undertaken before the opening of the new line, and people's actual (new) behaviour was surveyed after the new line opened. It is therefore possible to analyse the validity of the simulation (Section 3).     

A data-driven approach for origin–destination matrix construction from cellular network signalling data: a case study of Lyon region (France)

Transportation - Spatiotemporal data, and more specifically origin–destination matrices, are critical inputs to mobility studies for transportation planning and urban management purposes....     

Intérêt du modèle ? Hurdle ? pour la comparaison des comportements de mobilité déclarée dans un protocole d’enquête mixte

Due to decline in response rate to household travel surveys, it is essential that survey methods research explore the use of mixed-mode surveys. With this in mind, the Laboratoire d??économie des transports (Transport Economics Laboratory) conducted a web-based survey on non-respondents to a face-to-face household travel survey administered in the Lyon urban area in 2005?C2006. Comparative analysis of the figures shows that, overall, face-to-face respondents travel more than web-based respondents. This difference is partly explained by a high proportion of individuals who did not travel on the survey reference day and also by a lower trip level for those who travel. Classical regression methods can explain the individual mobility level with individuals socioeconomic characteristics, but do not take account of individuals who did not travel during the survey reference period. Using two econometric methods (simple Poisson and Hurdle Poisson regression) we examined factors affecting the decision to travel on one hand and the level of mobility on the other hand. This involves estimating the average daily mobility of individuals as a function of their socioeconomic characteristics while taking into account the fact that for a considerable part of the survey population, daily mobility is nil. Our approach intends firstly to define the causes of immobility better and secondly to characterise the mobility level with the help of a Hurdle model, so as to compare the results obtained in the web-based and faceto-face samples.