SIEMENS Verkehrstechnik has signed a co-operation agreement with FA Porsche for the development of a design-led production concept to build modular metro vehicles. The MoMo concept has been under development for the last 18 months, starting with the technical features and then moving on to interior fittings and image.According to the Project Manager for heavy rail product development Dr Michael Paula, MoMo is not intended to offer standard vehicles as such. Instead the range will comprise a wide selection of components and fittings from which a design will be assembled. Porsche will be responsible for developing the overall look for all new orders, drawing on the best options from the standard components. Should the customer want to go outside the standard range, he would be expected to pay more.As the MoMo concept emphasises the individuality of design for each customer, Siemens has not produced any prototype trains. However, Paula says that elements of the concept are being incorporated in the new fleets on order for Wien and Puerto Rico. The first cars for Tren Urbano have been completed at the Siemens STS plant in Sacramento, and a prototype six-car set for Wien is due to roll out early next year.