Modelling of 3D structures using a CAD like pre-processor including definition of project axis in plan and elevation. The 3D structure is analysed allowing the simulation of any erection procedure linking the erection with to the time axis in the calculation (4D). There are no limitations regarding bridge type and erection sequence. 14 international design code are currently incorporated and the program carries out specific SLS and ULS design code checks in accordance with these standards. The program is in use by many international consultants and a few thousand bridges worldwide have been designed using this powerful engineering tool.