Portable platform for use, for example, as a temporary road, comprising a flexible plastic material in which is embedded a composite reinforcement comprising two layers of parallel transverse metal cords and sandwiched between the two layers a layer of textile reinforcement and a layer of longitudinal parallel metal cords, the layer of longitudinal cords lying between the textile reinforcement and the load-bearing surface of the platform so that ''''one way'''' longitudinal rigidity is achieved.