Transport Survey Methods: Keeping up with a Changing World

At the 2008 International Conference on Transport Survey Methods in Annecy, France, transport survey methodologists and practitioners shared their experience with keeping abreast of the data needs of a rapidly changing world. Over the past decade, this has translated into the need for: an expanded travel survey toolkit; methodological innovation for surveys of freight and public transport operations; a growing use of data collection and processing technologies; a need to align surveys with other data streams; and an increased interest in the comparability of international datasets on personal travel and commodity movements in an era of globalisation. We discuss how these guided the choice and scope of the five themes around which both the Annecy Conference and this book were organised.

The purpose of this chapter is to provoke thinking about the directions in which the travel survey toolkit should move in the near future based on the author's personal experience and as an outcome of the Travel Survey Methods conference. The chapter begins with a brief historical review that attempts to show some of the major elements of change that have occurred in travel survey methods over the past 40–50 years. A more detailed review is provided about developments over the past 10–15 years. The chapter then explores a number of emerging challenges, including telephone contact of potential respondents, computer-assisted surveys, Internet surveys, mixed-mode surveys, the impacts of language and literacy and the potentials of mobile technologies. Based on this, the chapter then considers future directions that should be pursued. The chapter suggests that it has been changes in survey methodology that have, in the past, sometimes enabled and at other times led to changes in modelling paradigms, and that this may be an appropriate time for travel survey methodology again to enable changes in modelling paradigms. A speculative specification of a new household travel survey that makes use of a number of these developments is then offered. The chapter ends with some concluding remarks that issue a challenge to the travel survey community to think ‘outside the box’ and foster change and improvement in the accuracy and representativeness of travel surveys.

The increasing prominence of environmental sustainability as an objective of transport policy, and in people's thinking about their travel-related decisions, brings new challenges for data collection because, uniquely in the transport sector, it brings three issues to the fore: firstly, the difficulties associated with gathering data and opinions on a topic which is socially and morally charged; secondly, the fact that the resulting adjustments to behaviour may be in dimensions (such as choice of vehicle characteristics and mode choice for infrequent trips) which are not traditionally covered very fully in travel surveys; and thirdly, the likelihood that any change in behaviour may emerge only slowly over an extended period of time (as and when the opportunity arises for the individuals' behaviour to be adjusted to fit their aspirations).

It is argued that, because the topic is socially charged, data on sustainable travel behaviour is particularly prone to social desirability bias and other related biases. The nature and implications of these biases are addressed and it is concluded that individuals will tend to exaggerate the likelihood of behavioural change in response to sustainability concerns and policy initiatives. Methods, which might be used to study the emergence of sustainable patterns of behaviour in general, and responses to sustainability orientated policy initiatives in particular, are discussed and attention is given to ways of minimising bias in the data.

Increasing interest in ‘soft’ policy approaches to travel demand management, poses the question of how to measure the effectiveness of interventions. Much of the focus has been on statistical reliability of measured change where sample surveys are the primary means of estimating change. Sample surveys also pose issues of non-sampling errors, especially when the ‘measure’ is the difference between ‘before’ and ‘after’. This paper outlines the principles and pitfalls in measuring behaviour change. It draws on voluntary travel behaviour change (VTBC), using a number of approaches, including but not limited to Individualised Marketing (a method developed by the authors). A key issue in VTBC is the extent to which repeated experience can validate the effectiveness of voluntary behaviour change interventions in general, despite statistical errors of individual measurements. Measurement is fundamental to evaluation of outcomes. It can also aid the selection of locations with high potential to achieve change through identification of key success factors. In the specific case of travel behaviour change, there is now a substantial body of research that potentially allows outcomes to be related to other factors. To date, no strong relationships have been identified, but this would be a useful area for further research. Experience does demonstrate, however, that the scale of the intervention is important. Interventions with more than 5000 households are consistently more successful than small ones, even allowing for the greater statistical variability of measurement for smaller projects. Large scale also offers opportunities for intervention design to benefit from the potential for diffusion beyond those directly involved in the project.

Surveying hard-to-reach groups is difficult but necessary to prevent selection effects and biased sampling. Their diversity makes it difficult to recommend efficient solutions because they bring challenges that are specific to each group. Among these are limited ability in official languages, literacy problems, physical or mental disabilities or the particularities of subgroups such as ethnic, religious and cultural minorities, adolescents and the elderly. Drawing notably on lessons from migration research, this paper reviews the contemporary issues associated with five sets of circumstances that may result in groups being unreached by transport surveys.

Health scientists and urban planners have long been interested in the influence that the built environment has on the physical activities in which we engage, the environmental hazards we face, the kinds of amenities we enjoy, and the resulting impacts on our health. However, it is widely recognized that the extent of this influence, and the specific cause-and-effect relationships that exist, are still relatively unclear. Recent reviews highlight the need for more individual-level data on daily activities (especially physical activity) over long periods of time linked spatially to real-world characteristics of the built environment in diverse settings, along with a wide range of personal mediating variables. While capturing objective data on the built environment has benefited from wide-scale availability of detailed land use and transport network databases, the same cannot be said of human activity. A more diverse history of data collection methods exists for such activity and continues to evolve owing to a variety of quickly emerging wearable sensor technologies. At present, no “gold standard” method has emerged for assessing physical activity type and intensity under the real-world conditions of the built environment; in fact, most methods have barely been tested outside of the laboratory, and those that have tend to experience significant drops in accuracy and reliability. This paper provides a review of these diverse methods and emerging technologies, including biochemical, self-report, direct observation, passive motion detection, and integrated approaches. Based on this review and current needs, an integrated three-tiered methodology is proposed, including: (1) passive location tracking (e.g., using global positioning systems); (2) passive motion/biometric tracking (e.g., using accelerometers); and (3) limited self-reporting (e.g., using prompted recall diaries). Key development issues are highlighted, including the need for proper validation and automated activity-detection algorithms. The paper ends with a look at some of the key lessons learned and new opportunities that have emerged at the crossroads of urban studies and health sciences.

We do have a vision for a world in which people can walk to shops, school, friends' homes, or transit stations; in which they can mingle with their neighbors and admire trees, plants, and waterways; in which the air and water are clean; and in which there are parks and play areas for children, gathering spots for teens and the elderly, and convenient work and recreation places for the rest of us. (Frumkin, Frank, & Jackson, 2004, p. xvii)

Surveys of the public have been conducted to document and explain evacuation behaviour in a wide range of threatening events during the past half-century. Many of the behaviours are directly applicable to transportation modelling and management: whether people evacuate, when they depart, where they go, the routes they employ and the number of vehicles they use. Data have usually been collected by telephone interview or mailed questionnaires. Traditional survey methods should be supplemented by Internet surveys, traffic counts and GPS tracking. More real-time data collection should be employed to document a wider range of behaviours during a threat more accurately and to better understand the dynamics of evacuation decisions.

The importance of tourism for France's economy and society means that proper knowledge of tourism flows is essential. But designing a measuring system and periodic gathering of statistical data raise several difficulties. First, tourism is, by definition, based on movement, and all phenomena involving movement are difficult to measure. Second, there are many different forms of tourism, including holidays and business trips, short and long stays and so forth. Third, the notion of tourism flows has different meanings for those in charge of road, rail or air traffic management, and for those in charge of tourist visits.

This paper first discusses the ambiguities of the notions used in tourism studies. It emphasises the distinction between tourist flows along transportation routes and those in specific places. It then reviews the proper calculation rules for each of the geographical objects used for measuring tourism phenomena, which are primarily lines and areas. It also addresses some of the problems raised by the failure to comply with these rules in published information.

Third, this paper presents the various systems used to measure tourist flows and inflows, and discusses their usefulness and limitations, before discussing some new developments in the field.

Finally, it examines the potential value of modern communication technologies for mobility studies. More specifically, it raises the issue of striking the right balance between statistical accuracy and individual freedom.

This paper provides an extensive review of surveys and data-collection programmes focused on urban goods movement (UGM). Surveys investigating passenger urban travel have a decades-long tradition. The same is not true for UGM. The first specific UGM surveys appeared about 10 years ago in response to the rapid growth of car traffic, congestion, pollution and lack of space. Most of the time, these surveys have been carried out to resolve specific, local problems concerning traffic. Only a few of them have taken a global approach to urban logistics by including all logistics operators (own-account and carriers), all delivery vehicles (heavy and light vehicles), all deliveries and pickups (from express to full payload) and an entire metropolitan area and surroundings. Due to various European programmes, an inventory has been created to analyse urban goods data collection according to spatial level and methodology of capture. With this inventory, European urban freight indicators can be described, along with the units in which they are measured and their purposes. The relevance of urban goods transport surveys lies in their capacity to give decision-makers an account of urban freight transport functioning, ratios and data, so as to help in formulating planning, regulation and forecasting. It appears that focusing on the movement (delivery/pick-up), as the unit of analysis in establishment-driver surveys is the most efficient approach to describe the generation of vehicular flow in the city. This fact is revealed in the French UGM surveys, which take into account the complexity of urban logistics.

This chapter examines the systems used to collect data on the long-distance movement of freight by road for modelling, market research and other purposes. It begins by listing the features of an ideal long-distance freight data set that would fully meet the needs of policy makers, business analysts, academic researchers and freight operators. It then reviews the existing data-collection systems in Europe, highlighting their shortcomings and how they might be overcome. The third section analyses the strengths and limitations of several alternative approaches to collecting and analysing road freight data, some of which are at an early stage of development.

More than ever before, public transit must compete in the transport market. This competition is, on the one hand, against steadily increasing car traffic; and on the other hand, between public transit operators. This, in turn, leads to new demands regarding the type, content and quality of data needed for planning and management. Frequently, traditional travel behaviour surveys do not provide sufficiently accurate and detailed information about public transit demand. To plan public transit, frequently a precise description of all trip stages, including the first and the last mile, is necessary. To achieve this, an adaptation of the traditional survey methods is necessary. In many countries, public transit associations have been established to integrate services offered by individual public transit operators with the help of through-ticketing and a coordination of lines and timetables into what looks, to the user, like a single system. To distribute revenue among the operators involved, detailed surveys of passengers are needed. Measuring the quality of public transit service and surveying customer satisfaction are new tasks. Such data are the basis for quality assurance and are essential for gaining and keeping customers of the public transit system. New technologies such as the Global Positioning System, automated passenger counts and Smart Card Payment Systems offer new possibilities to collect data more efficiently and cost-effectively. This article covers essential aspects of surveys and the collection of data that are crucial for the planning and management of public transit; it points to state-of-the-art methods and offers potential solutions.

In the recent past, mobile technologies that track the movement of people, freight and vehicles have evolved rapidly. The major categories of such technologies are reviewed and a number of attributes for classification are proposed. The willingness of people to engage in such technologically based surveys and the reported biases in the make-up of the sample obtained are reviewed. Lessons are drawn about the nature of the samples that can be achieved and the representativeness of such samples is discussed. Data processing is addressed, particularly in terms of the processing requirements for logged data, where additional travel characteristics required for travel analysis may need to be imputed. Another issue explored is the reliability of data entered by respondents in interactive devices and concerns that may arise in processing data collected in real time for prompting or interrogating respondents. Differences, in relation to the data user, between data from mobile devices and data from conventional self-report surveys are discussed. Potentials that may exist for changes in modelling from using such data are explored. Conclusions are drawn about the usefulness and limitations of mobile technologies to collect and process data. The extent to which such mobile technologies may be used in future, either to supplement or replace conventional methods of data collection, is discussed along with the readiness of the technology for today and the advances that may be expected in the short and medium term from this form of technology.

Over the past decade, transportation researchers have leveraged global positioning system (GPS) technology to improve the accuracy and increase the depth of spatial and temporal details obtained through household travel surveys. While earlier studies used GPS as a supplement to traditional household travel survey methods, measuring the accuracy of trips reported (Wolf et al., 2006), studies are now underway to identify the methods and tools that will allow us to do away with paper diaries entirely and simply rely on GPS to obtain trip details. This paper finds that while GPS clearly helps to improve participation among some groups, it decreases participation among others. Thus, it should be considered a tool in the household travel survey toolbox and not “the” solution to non-response issues in household travel surveys.

In this chapter, we address the question if and how modern technology can be used to design questionnaires, diaries, web sites, and experiments to improve the validity of reliability of active data collection instruments. In particular, it discusses the history of computer-assisted activity diary data, reenactment sessions, stated preference methods, and interactive computer experiments with a special focus on the design of these instruments in terms of respondent support and user interfaces. Empirical evidence and experience suggests that although fascinating instruments may increase respondent motivation and involvement and therefore improve the reliability of the measurements, there is also the danger that respondents' answers are influenced by features of the electronic instrument that are not essential, reducing validity and reliability.

New computer-assisted techniques for visualizing data are evolving in a number of areas in transportation. For example, in engineering, 3D visualization and microsimulation techniques are being applied for the identification and evaluation of geometric and operational solutions for improving visually impaired pedestrian access to roundabouts and channelized turn lanes. For planning, visualization is being used for corridor analysis. Data visualization is being used as a tool for improving decision-making within transit agencies, as well as a tool for understanding truck trip generation on highways. Many of these new techniques take advantage of archived intelligent transportation systems (ITS) data. Examples of other innovative data sources include global positioning systems (GPS), geographic information systems (GIS), computer-aided design (CAD), and a variety of visualization tools available for use with travel survey data. As these various techniques and software applications move forward, consideration needs to be given to how the “lessons learned” from these applications can facilitate the use of data visualization techniques for travel survey data analysis and decision-making.

Large-scale continuous mobility surveys have some advantages over less frequent (usually every 10 years), even larger-scale cross-sectional surveys; these advantages have been well documented in previous papers (Ampt & Ortúzar, 2004).

In this paper we first define what we mean by ‘ongoing mobility surveys’. We then describe the state of practice in this context, briefly reviewing the state of affairs in all the cases that we are aware of. We then discuss some problems encountered in practice and offer ideas for improvement. In particular, we discuss a wide range of issues that are likely to act as barriers to a high quality and sustainable implementation and suggest approaches for improvement. Issues covered include sampling frames and sampling methods, survey methods, respondent burden, weighting processes and expansion, and the increased importance of developing and maintaining field staff motivation. We also touch briefly on the practical/political issue of securing ongoing funding. Throughout, we advance some thoughts to try and explain why this method has not gained wider acceptance, particularly in the Northern Hemisphere where there are more examples of travel surveys in general.

The paper also raises some ideas and issues about the way in which ongoing mobility surveys can best collect data for the environmental accounting of travel. Finally, we raise questions about the environmental impact of the survey methods themselves as a stimulus for further consideration.

Across Europe, on average more than 95% of all passenger cars and half of all light commercial vehicles are permanently available to a household. This includes both privately owned vehicles and company cars. The profiles of vehicle use can be specified as average annual distance driven per vehicle and for the fleet as a total, purpose of travel (trip destination), infrastructure use (urban, interurban or motorway road transport) and also fuel consumption together with data on CO₂ emissions. Indicators on vehicle use can be tracked in various ways:

• self-administered panels of households, which permit their vehicles to be followed for several years;

• national or local household travel surveys (with a seven-day trip diary);

• official vehicle inspection and vehicle registration files;

• ‘vehicle surveys’ based on vehicle registry data;

• traffic counts;

• data collected for road-charging purposes.

self-administered panels of households, which permit their vehicles to be followed for several years;

national or local household travel surveys (with a seven-day trip diary);

official vehicle inspection and vehicle registration files;

‘vehicle surveys’ based on vehicle registry data;

traffic counts;

data collected for road-charging purposes.

The paper will present a review of mainly vehicle-based survey methods used in France, Germany, Finland, the United Kingdom, the United States and Canada, describing existing sampling frames to their scope, advantages and limitations, as well as their costs. Issues addressed in this context will be further examined in terms of their methodological challenges as well as their purpose.

The leading questions underlying this paper as well as the corresponding workshop are: why is it necessary to have data on passenger travel or transportation; and, looking at international experience, how good are vehicle-based surveys in delivering the required information? In discussing problems experienced in the different countries with data collection and evaluation methods, emphasis will be put on potential strategies for methodological and technological improvement and problem solving. One example is the potential use, benefits and constraints of new survey technologies presented by vehicle tracking techniques.

Data fusion and the combination of multiple data sources have been part of travel survey processes for some time. In the current context, where technologies and information systems spread and become more and more diverse, the transportation community is getting more and more interested in the potential of data fusion processes to help gather more complete datasets and help give additional utility to available data sources. Research is looking for ways to enhance the available information by using both various data collection methods and data from various sources, surveys or observation systems. Survey response rates are decreasing over the world, and combining survey modes appears to be an interesting way to address this problem. Letting interviewees choose their survey mode allows increasing response rates, but survey mode could impact the data collected. This paper first discusses issues rising when combining survey modes within the same survey and presents a method to merge the data coming from different survey modes, in order to consolidate the database. Then, it defines and describes the data fusion process and discusses how it can be relevant for transportation analysis and modelling purposes. Benefiting from the availability of various datasets from the Greater Montréal Area and the Greater Lyon Area, some applications of data fusion are constructed and/or reproduced to illustrate and test some of the methods described in the literature.

This chapter summarizes some of the results from the Working Group “National Travel Surveys” in COST Action 355. All 50 presentations could not be reviewed here; thus, we focus on three crucial topics:

• the periodicity of data collection, but also its longitudinal aspects (advantages of continuous surveying, repeated cross-sections vs. panel surveys, etc.),

• new technologies for improving the efficiency and accuracy of mobility surveys (computer-assisted telephone, Web-based, interviews, GPS, GSM, RDS, etc.),

• innovative approaches, exemplified by qualitative surveys combined with conventional quantitative ones, and by biographical approaches.

the periodicity of data collection, but also its longitudinal aspects (advantages of continuous surveying, repeated cross-sections vs. panel surveys, etc.),

new technologies for improving the efficiency and accuracy of mobility surveys (computer-assisted telephone, Web-based, interviews, GPS, GSM, RDS, etc.),

innovative approaches, exemplified by qualitative surveys combined with conventional quantitative ones, and by biographical approaches.