Validation consists of an appraisal of the requirements proposed during the definition phase, in an operational environment and under the critical eye of the operational experts.

ADV practiced various validation techniques, having each one their own interest:

• Expert judgment i.e. a critical review of the requirements by a panel of operational peers, for instance through surveys, interviews, expert groups, dedicated workshops, user forums, prepared and organized by ADV;
• Analytical and macro modelling i.e. a simplified, high-level representation of the systems’ behaviour to infer trends and macroscopic results in representative situations;
• Simulations i.e. the virtual and automated emulation of the future system powered by IT means. They may range from fast-time simulations (quick but rough) to real-time simulations (time-consuming but accurate) through gaming (involving live interactions of operational actors);
• Shadowing in which the system prototype is run in the background, parallel with the current operational systems;
• Live trials in which the new system takes over from the current one, under restricted, well-defined operational conditions.