Complex systems are systems composed of different components that interact with each other. A well-known example of complex systems are the so-called intelligent transportation systems (ITS). In such systems, amongst others, the environment is highly dynamic. Complex systems often manifest rich, non-trivial and unexpected behaviours. Examples of transportation-related complex systems are: road traffic, traffic sensors, autonomous/automated cars, smart cities, smart sensors, virtual sensors, traffic control systems, smart roads, logistics systems, smart mobility systems, etc.

There are several challenges that constitute very interesting research problems, which should be solved appropriately. For example, the increasing number of vehicles and inhabitants, the low support of secondary infrastructure, the costs and the safety requirements, etc. are challenges that lead to a trade-off to balance between the engineering solutions, costs, environment, and safety. However, to master the efficient operation of various transportation-related complex systems, a series of sensor/sensing, data quality, online simulation, and modelling- and optimization-related issues are of extreme high actual interest. Additionally, solving the previous problems lead to efficiency, for example, w.r.t. public transport, private transport, travel comfort, ticketing systems.