The SrV standard
Table of contents
Scope
Since the target population of the SrV survey consists of the residents of a city or municipality, the mobility of the residential population constitutes the central subject of the study. It is assumed that the trips made by the residential population contribute significantly to the overall travel volume within a study area. Other relevant forms of transport, in particular trips by non-residential commuters, tourists, and visitors, are not considered in the SrV. Commercial transport is only recorded to a limited extent, as far as work-related passenger transport (work-related trips undertaken as part of professional duties; commuting excluded) occurs as part of residents' trips.
Survey characteristics
The survey collects structural characteristics of households and their members, as well as behavioral personal data and trip data for a given reporting day. The standard SrV questionnaire covers a wide range of characteristics relevant to transport planning. Many commissioning institutions use the possibility to adapt and expand the set of queried characteristics by means of additional questions. The complete list of questions of the last SrV iteration is documented in the SrV 2023 Methodology Report (Appendix II).
Survey design
The survey design is characterized by certain standard features to ensure a continuous and comparable time series:
|
Population |
Urban residential population |
| Questionnaire | Household, individuals, trips |
| Definition of trips | Change of location with exactly one purpose, can involve several means of transport |
| Main mode of transport |
Hierarchy of modes of transport |
| Sampling | Random sampling from the register of residents |
| Surveyed individuals | All household members |
| Surveyed trips | All trips on a randomly assigned reporting day |
| Reporting day | Mid-week working day (Tue, Wed, Thu, excluding school holidays, public holidays, and holiday-adjacent days) |
| Reference period | Mean annual transport volume |
| Field work period | 12 months |
| Weighting | According to sociodemographic as well as spatial and temporal characteristics |
| Results | City specific, city groups, city comparison |
Sampling
The target population consists of all residents of the respective SrV study area. The municipal register of residents forms the basis for random sampling. There are no restrictions regarding age, nationality, or main versus secondary residence.
Ideally, the sample size should be determined based on the required level of accuracy. At the same time, however, it is limited by the available financial resources. The sample size is therefore always a compromise between analytical requirements, accuracy, and cost. In the SrV standard case, the required sample size for a predefined level of accuracy is traditionally determined based on the number of trips (specific travel volume) and the modal split at the citywide level. The minimum SrV sample size for larger cities is based on the fact that 1,000 respondents are required, assuming unrestricted random selection, to estimate the specific travel volume for the entire city with a 95 percent confidence level and an accuracy of ± 4 percent. The same sample size also allows the modal split (share of private motorized transport) to be determined with an accuracy of ± 2 percent. Higher levels of accuracy or differentiated results for subareas within the city require larger samples. As a general rule, doubling the statistical accuracy requires a fourfold increase in sample size.
Transport relationships between subareas within a study area can generally not be represented with this data. However, SrV data are suitable for use in transport models, which are typically used to calculate such transport relationships.
Analysis
The analysis of the collected data is carried out in a standardized manner for each study area according to a catalog of indicators (as reflected in the standard tables 1.1 to 11.3 in the Tabular Report for the city group SrV Large Cities East). Maintaining this structure makes it easier to retrieve comparable indicators from different survey iterations. Nevertheless, the analytical framework is regularly reviewed and adapted to current requirements.
In addition, participating cities and municipalities may commission more detailed analyses of particular city-specific issues, within the limits of the respective sample.
Presentation of results
The results for each survey area always include the SrV Mobility Fact Sheet, the SrV Tabular Report, and a field report. If analyses for subareas have been commissioned, additional fact sheets and tabular reports are delivered. The results of the survey also include the Methodology Report, the SrV City Comparison, and the reports for the SrV city groups.
The reports for the city group SrV Large Cities East, i.e., the SrV 2023 Tabular Report (standard tables 1.1 to11.3) and the Mobility Fact Sheet, provide an overview of the contents of the city-specific reports.