The monograph contains the results of research devoted to determining the vulnerability of passenger road transport in Poland by identifying the nature and scale of changes in transport accessibility and changes in the network traffic load in the event of a flood (with different probabilities of occurrence), conducted under the project number 2018/29/B/HS4/01020, financed by the National Science Center in Poland. In the course of the implementation of such formulated main goal of the study, an attempt was made to achieve a group of specific objectives of a cognitive, methodological and application character. The research was conducted mainly on the basis of data on the extent of flood risk areas in Poland and their development, as well as the road network and the development of its neighborhood. The publication may be of interest to researchers dealing with the geography of transport or – more broadly – with socio-economic geography and spatial management. It can also be helpful material for students of study programs that relate to the geography of transport, transport accessibility or spatial mobility in their curriculum. The content of the thesis covers issues that can be used by specialists in crisis management or road infrastructure management in crisis situations related to the occurrence of a flood.