The experience of the implementation and execution of several surveys of travel behaviour of the members of two Zurich universities are described. Today around 50000 people work and study at the institutions based in a central area of the city. As part of the planning process the Municipality of Zurich encouraged an assessment of the impacts of the expected 20% increase in employee and student numbers following the construction of a 150000m2 additional gross floor area. A variety of survey protocols was tested, as the comparative efficiency and selectivity of the different protocols is an under-researched area. The surveys for the different groups of users in the study area were conducted with different methods over the time period from November 2006 to December 2007. The protocols differed along two main criteria: the surveys were conducted via a browser based survey application and by pen-and-paper questionnaires. Some of the surveys were full travel diaries (in different variants), others only recorded the respondents' trips to and from the institution, but for a weekly reporting period. The surveyed included all students and employees of the universities as well as all employees, and samples of the patients and visitors of the University Hospital. The aim was to provide a sample of all traveller categoriesrelevant to the assessment of travel demand to and from the major institutions, as well as enough variability in the population in order to assess the differences in response behaviour based on socio-demographic characteristics and the different protocols and contents. The allocation to the different methods resulted on the one hand from the accessibility of the interviewees and their access to the web. For some subgroups the impact was ofselected administrative variables on selectivity in their participation. Difficulties that were experienced during the execution of the surveys were also discussed. Special consideration will be given to the technical problems with the online surveys, their impact on data quality and the continuous attempts at resolving them. Thus, the scope of the paper will be to explain the differences in response behaviour for the varying survey methods based on assessments of response burden and accounting for the structural differences between the user groups. Data quality issues resulting from the survey designs, such as non-response to single items, aborted interviews and incomplete questionnaires, will also be discussed. A brief description of the main findings is presented. It is shown that a large portion ofthe existing travel demand in the area is indeed generated by the three institutions under examination, and that the expansion could potentially lead to overloads of the transport system. This holds especially for public transport, which accounts for an exceptionally large share of trips to theperimeter. For the covering abstract see ITRD E145999
Samenvatting