The time from the second half of the last century up to the present is characterised by a rapid growth of cities and urban agglomerations. Around 80 percentage of the total European population is currently living in urban areas (cf. EUROPAISCHER WIRTSCHAFTS- UND SOZIALAUSSCHUSS 2008, p.125).

In practice, however, the increasing prosperity is linked to high resource consumption and environmental damage. Climate change and resource scarcity pose global problems to the world, which, however, require locally responsible behaviour from each individual person, community, industrial sector etc. In this context, the cities and their transport systems are faced with major challenges. This thesis has the objective to develop and present an "urban comparative analysis" as an assessment and an orientation tool for passenger transportation systems of big cities.

The aim of this urban comparison is to define the transport system's potential for improvement and thus to serve as a support instrument for targeted measures. It should be shown and explained how to conduct and organize the comparisons of transportation systems in passenger transport of big cities in order to achieve the goals of the comparison. A regularly conducted urban comparison can help to recognize changes in the system early and thus avoid negative impacts or potential wrong turns in planning.

The starting point of this thesis is the realization that comparison as a type of human thinking is already an instrument for gaining knowledge. Sustainability, defined as the lasting preservation of an intact system, is a central assessment factor in this urban comparison. This includes:

• lasting preservation of intact ecosystems,

• lasting economic stability and security both of the entire system as well as of its subsystems (e.g. private households),

• lasting social security, fair livelihood opportunities and quality of life.

This thesis primarily focuses (focuses primarily) on public transport's relative contribution to sustainability. The comparative method is presented in an urban comparative analysis of three Western European cities: Vienna, Berlin and Madrid.

This work also answers questions on the selection of the compared cities, of valuation method and of the indicators. It also provides additional tips required to apply the instrument "urban comparative analysis" most effectively.