The first part of the paper gives a definition of positioning in the context of road worksites and stresses the advantages brought by the new positioning systems. A logical classification of these systems is also proposed. One technique in particular which seems to be more promising at the moment : the Global Positioning System (GPS), is detailed. Then the new test facility for positioning systems, existing at the Laboratoire Central des Ponts et Chaussees (Central Laboratory of Bridges and Roads) is described, our Laboratory having decided to play a major play in the evaluation and development of systems adapted to road construction. At last, some results from recent tests performed on a Ultra Precise Differential GPS on a kinematic mode are given. These tests have already produces some interesting results that would have been hard to obtain without the test facility.