Toll Gates in France

Four toll gates of this type have been erected along the Amiens-Boulogne motorway. The swift assembly of the prefabricated modular roof elements meant a minimum impediment to traffic. The precast concrete masts are anchored in sleeve foundations. A 17 ? 17 m square frame, consisting of trussed girders with diagonal bracing, is suspended from the tip of each mast by four rods. The Teflon-coated, self-cleaning, polyester membrane is spanned between the frame and a lower steel ring. The seams between the segments of the membrane are reinforced with strips that bear most of the radial tension loads. Connected to the foot of the pylon by rods, the ring serves to tension the membrane and stabilize the structure.