Data included in the World Roads Statistics (WRS) is collected by conducting an annual survey sent to IRF-Geneva’s exhaustive network of local and official primary statistics sources in over 200 countries.
This annual survey uses a questionnaire, in four different languages (English, French, Spanish and Russian), to collect data on the nine sections of the WRS and for the last years. The survey is initiated in January of each year and completed in August of the same year.
The data collected from the survey is complemented by using national statistics from secondary sources such as official yearbooks.
The validity of the data is checked in several ways; comparisons with data from various sources, comparison with historical data, reconciling the definitions of indicators, and by checking the validity of questionable data by going back to our network of national contacts.
One of the most important aspects of producing these statistics is to ensure that the data needed for specific indicators is consistent across countries and over time.