For this test, an artificial test track, simulating an irregular ground is used. This test track consists of two parallel strips of steel mesh (6 m long and 400 mm wide), fastened in the reflecting plane approximately every 20 cm. The distance between the two strips is adapted according to the type of container, in order to allow the wheels to roll all over the whole length of the track. The mounting conditions shall ensure a flat surface. If necessary, the track is fastened on the ground with resilient material to avoid emission of parasitic noise.