"The certification of a rail vehicle according to European regulations, Technical Specifications for Interoperability, European Standards and national safety rules represents a significant element of both vehicle cost and time to market. Indeed, a large part of vehicle certification mandates testing for safety, performance and infrastructure compatibility. AEROTRAIN will help meet the business scenarios listed in the ERRAC SRRA 2002 and 2007 by aiding the spread of European homologation and acceptance procedures to speed up interoperable product approvals while squeezing out risk through improved safety management. In the field of aerodynamics a recent EN focuses on common definitions and descriptions of the aerodynamic phenomena and measurement procedures. Due to the application to all types of rail traffic it has not converged yet to one method per phenomenon but allows variations arising from national rules. The focus of the project is therefore on using the TSI route to consolidate the methodologies allowing the free exchange of certification data.The project is part of the TRIO-TRAIN cluster (Total Regulatory Acceptance for the Interoperable Network) which comprises 3 related projects dealing with key railway interoperability issues: Aerodynamics (AEROTRAIN), Railway Dynamics and Track Interaction (DYNOTRAIN) and Pantograph/Catenary Interaction (PANTOTRAIN) all submitted under the 2nd Call of the FP7. The objective of these projects is to propose an innovative methodology via a computer simulation/virtual homologation that will allow multi-system network and route approval in Europe to become a faster, cheaper and better process for all involved stakeholders. Therefore the success of the TRIOTRAIN cluster will lead to a time reduction for relevant parts of the certification process from 24 to 6 months; an 80% saving in effort for the acceptance of a new vehicle already accepted in an other country and an estimated financial saving of €20-50 Million/year."