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Comparative experimental application of alternative travel diaries in Cape Town and Dar es Salaam
| Content Provider | Semantic Scholar |
|---|---|
| Author | Behrens, R. Jun. Masaoe, Estomihi N. |
| Copyright Year | 2009 |
| Abstract | Internationally, travel diaries of various forms have served as the principal means of collecting revealed preference travel data. Household interview travel survey experiences in African cities, however, have demonstrated that the collection of travel diary data is problematic for both respondents and interviewers. This paper reports on the development of a travel diary instrument for use in a planned 24-hour recall home interview survey in Cape Town, Dar es Salaam and Nairobi. As part of the development of this survey instrument an experiment was undertaken to assess the appropriateness and feasibility of different travel diary forms. In other parts of the world travel diaries have taken three main forms: trip-based, activity-based and place-based diaries. Variations of these three basic diary forms include: the recording of trips in either tabular or sequential question format; the prospective or retrospective request for respondent recall; and the use of memory joggers. The paper describes the impact of alternative travel diary forms on respondent burden, trip and trip stage recall rates, interviewer cognition and item recording or nonresponse errors, and respondent cognition and item recording errors. On the basis of the experiment findings, it is concluded that place-based diaries in sequential question format, with associated memory joggers, are likely to yield highest rates of trip recall and lowest rates of measurement error and item non-response in city contexts with respondent populations similar in socio-demographic nature to those in Cape Town and Dar es Salaam. INTRODUCTION A travel diary survey is planned in the cities of Cape Town, Dar es Salaam and Nairobi in 2009 (n = ±3,000 household). A travel diary is an instrument designed to record all the movements of a person over a prescribed period of time, typically accompanied by a ‘person instrument’ recording person specific information, a ‘household instrument’ recording relevant information relating to the household, and a ‘resource instrument’ recording relevant details concerning the means of travel and communication available to the household (Axhausen 1995). Travel diaries enable relatively rich data on travel behaviour to be collected fairly efficiently, and enable relative measurements of all trip purposes across the entire day, by all travel modes. This data comprehensiveness and richness, however, comes at the cost of greater complexity and respondent burden. For this reason many travel surveys in Sub-Saharan Africa have tended to omit them in favour of simpler instruments concentrating on a limited set of trips or types of passengers regarded by the commissioning agency to be of greatest importance. For example, work and education trips in the case of the South African Department of Transport’s National Household Travel Survey of 2003, and work, business, education and social trips in the case of the household travel survey carried out in Dar es Salaam in 2007 as part of the development of the city’s transport master plan). Nevertheless, travel diaries have become a fairly standard feature of representative sample national household travel surveys or city-wide origin-destination studies elsewhere in the world, and the African practice of omitting them in survey instruments is somewhat atypical in the field. In contexts where diaries are commonly applied, growing concerns about the completeness and quality of the travel data collected, particularly through telephonic interviews and self-completed mail-back surveys, have led some authors to argue that they may one day be replaced by data collection methods using remote observation technologies (e.g. global positioning systems) that reduce respondent burden and potentially eradicate trip underreporting (see, for instance, Stopher and Greaves 2007, Stopher 2008 and Wolf 2000). It is argued here, however, that the need to collect travel data through diary methods is likely to remain, at least in the short term, particularly in developing world countries with relatively less data collection resources and capacity. Hence research directed at improving their reporting capability and reducing respondent burden is deemed to remain important and necessary. The purpose of this paper is to report on a travel diary experiment undertaken in Cape Town and Dar es Salaam as part of the preparation for the planned survey, and to draw conclusions with respect to which travel diary format is best suited to these city contexts. The paper is divided into six sections. The next section describes alternative travel diary formats. Section 3 discusses common problems reported in the application of travel diary surveys, particularly in Sub-Saharan African contexts. Section 4 explains the experiment’s objectives and method, section 5 discusses findings, and section 6 draws conclusions. ALTERNATIVE TRAVEL DIARY FORMATS Travel diaries can be categorised into three main groups, on the basis of their principal object of recall: trip-based diaries; place-based diaries; and activity-based diaries. The earliest form of travel diary, the trip-based diary, was developed in association with the early American city-wide transport planning studies in the 1960s and 1970s. Early trip-based diaries were completed by an interviewer in a face-to-face retrospective home interview (see Stopher 2008:5 for an illustrated example). The development of the earliest self-completed trip-based diary, the so-called Kontiv survey, is attributed to Socialdata in Germany in the late 1970s (see Brög et al 1983). Trip-based diaries essentially ask respondents to report each origin-to-destination movement they undertook over the diary period, without explicitly requiring that this reporting of trips is ordered chronologically. The information requested about each trip can vary, typically including, as a minimum, origin, destination, purpose, departure time, travel time, modes used, and main mode. A variant of the trip-based diary is the stage-based diary, in which each trip stage (as opposed to each trip) is reported. The next form of travel diary, developed in the 1980s, was the activity-based diary. Pioneering studies into activity-based travel behaviour analysis were undertaken by Oxford University’s Transport Studies Unit in the late-1970s and early-1980s (see Clarke et al 1981). Jones et al (1983:60) illustrate an early example of an activity diary applied in Banbury, Oxfordshire. In this survey seven-day activity diaries were collected from all household members. The premise of this and other studies was that it is not possible to understand how travel behaviour might respond to changes in the transport system, without a much deeper understanding of the everyday lives and activities within which travel decisions are embedded. In the activity-based diary, therefore, instead of asking first what trip was made, and later what the purpose of the trip was, the diary begins by asking the respondent what the next thing was that he or she did, and follows this by asking (if the respondent was not already there) how the respondent travelled to the place where this activity occurred. Importantly, the recall of activity participation is requested in chronological order for the entire diary period. Stopher and Greaves (2007) note that the trip rates derived from these diaries are around 20% higher than those found from trip-based diaries (corroborated by Behrens (2003) in an activity-based diary survey in Cape Town). The reason for this improved recall is argued to be that in activity-based diaries the respondent is required to account for his or her time continuously and is therefore forced to recall past events more rigorously, and that recounting activity participation (as opposed to trip-making) matches more closely the way people think and function. The most recent innovation in travel diary surveys, developed in the 1990s, is the place-based diary. This is essentially a hybrid of a trip-based and an activity-based diary, in which the respondent is asked where he or she went to next in chronological sequence across the diary period, and is then asked how he or she got there. Wolf (2000) reports that this diary format has also been found to improve trip recall relative to trip-based diaries. As in activity-based diaries, the place-based diary is an attempt to align the respondent recall process to a more intuitive way of thinking about, and recalling, daily travel. A variation across the main diary types, is the presentation of questions in either tabular or sequential question format. The rationale for the latter is that some respondents (and interviewers in the context of Cape Town at least) have been found to have difficulty in understanding table cells as a set of intersecting columns and rows. By presenting the questions sequentially the likelihood of recording information in the incorrect cells is reduced. A further variation is the use or not of ‘memory joggers’, typically in association with prospective diaries in which a future diary period is indicated at the time of respondent recruitment. The memory jogger is an abbreviated version of the actual diary that allows respondents to record the duration and nature of each trip or activity as it is undertaken. More detailed information on each trip or activity is then recorded in a dairy booklet later in the day when it is more convenient to do so in the case of self-completed diaries, or during a subsequent home or telephonic interview. COMMON PROBLEMS IN TRAVEL DIARY SURVEYS IN AFRICAN CITIES Before discussing the problems commonly encountered in administering diary surveys, it is perhaps useful to first clarify selected travel measurement concepts applied in the experiment. Figure 1 illustrates the following definitions: a trip is a movement between two activity stations; a trip stage is a part of a trip in instances where more than one travel mode is used; the travel mode covering the long |
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| Alternate Webpage(s) | https://repository.up.ac.za/bitstream/handle/2263/11902/Behrens_Comparative(2009).pdf?isAllowed=y&sequence=1 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
