  Timed automata (TA) have been widely adopted as a suitable formalism to model
time-critical systems. Furthermore, contemporary model-checking tools allow the
designer to check whether a TA complies with a system specification. However,
the exact timing constants are often uncertain during the design phase.
Consequently, the designer is often able to build a TA with a correct
structure, however, the timing constants need to be tuned to satisfy the
specification. Moreover, even if the TA initially satisfies the specification,
it can be the case that just a slight perturbation during the implementation
causes a violation of the specification. Unfortunately, model-checking tools
are usually not able to provide any reasonable guidance on how to fix the model
in such situations. In this paper, we propose several concepts and techniques
to cope with the above mentioned design phase issues when dealing with
reachability and safety specifications.
