The aim of the case study collection report is to gather, evaluate and comment on international expertise related to maintenance and traffic management in highly trafficked urban road tunnels. A large number of cases were collected, which were particularly suitable for providing an insight into the implementation of these special requirements for urban road tunnels.

It became apparent that it was useful to divide the cases into 3 categories, which pursued similar goals.

·Implementation of the "quick responders" concept with different approaches

·Measures to organize work and to reduce nuisance to users during the renovation of tunnels

·New tools for maintenance and operation

The quick responders approach is generally considered to be an appropriate measure. However, local requirements must be carefully considered. Specially equipped motorcycles are recommended as suitable responding vehicles.

In the second category, various approaches are possible, and these should be tailored as closely as possible to the renovation project in question. Public information campaigns can be just as important as technically sophisticated traffic guidance installations and design adaptations.

New tools such as BIM (building information modeling) and CAFM (computer aided facility management) derived from it are future methods of viewing tunnels like "machines" that can be calculated as digital twins. The maintenance status of the components is continuously monitored and measures are derived from this. Probabilistic approaches, e.g. on the basis of the RAMS ISO-standard (reliability, availability, maintainability, safety), can be used to take failure probabilities into account. Such methods are already in use in some cases, but are particularly effective if the methodology can already be deployed during the initial design and construction phase.