- Tread for a heavy vehicle tyre of width W, this tread having, when new, a tread surface intended to come into contact with a roadway, this tread comprising: - over at least a first axial part of the tread at least one wavy groove (2, 4) with waviness in the thickness of the tread and continuous in a first direction and a plurality of wavy grooves (6, 7) with waviness in the thickness of the tread and continuous in a second direction, each of these continuous wavy grooves extending between a first level corresponding to the tread surface when new and another level in the thickness of the tread, these wavy grooves comprising a plurality of open parts (21, 41, 61, 71) opening onto the tread surface when new and a plurality of closed parts (22, 42, 62, 72) underlying the tread surface, the closed parts being connected to the open parts and arranged in alternation, each closed part being spaced away from the tread surface when new by a bridge of rubber, the wavy grooves (6, 7) in the second direction being connected to at least one wavy groove (2, 4) in the first direction, - over at least a second axial part of the tread at least one wavy groove (1, 5) with waviness in the thickness of the tread and continuous in a third direction and a plurality of wavy grooves (6, 7) with waviness in the thickness of the tread and continuous in a fourth direction, each wavy groove comprising a plurality of open parts opening onto the tread surface when new and a plurality of closed parts, the closed parts being connected to the open parts, these open and closed parts being arranged in alternation, each closed part being spaced away from the tread surface by a bridge of rubber, the wavy grooves (6, 7) of this second axial tread part oriented in the fourth direction being connected to at least one wavy groove (1, 5) in the third direction, this tread being characterized in that: - when new, the open parts opening onto the tread surface of the first axial part are connected to one another to form a continuous surface network and in that the open parts opening onto the tread surface of the second axial part are disjointed from one another, - and in that beyond a part-wear condition, the open parts opening onto a new tread surface of the second axial part are connected to one another to form a continuous surface network and in that the open parts opening onto the new tread surface of the first axial part are disjointed from one another. - over at least a first axial part of the tread at least one wavy groove (2, 4) with waviness in the thickness of the tread and continuous in a first direction and a plurality of wavy grooves (6, 7) with waviness in the thickness of the tread and continuous in a second direction, each of these continuous wavy grooves extending between a first level corresponding to the tread surface when new and another level in the thickness of the tread, these wavy grooves comprising a plurality of open parts (21, 41, 61, 71) opening onto the tread surface when new and a plurality of closed parts (22, 42, 62, 72) underlying the tread surface, the closed parts being connected to the open parts and arranged in alternation, each closed part being spaced away from the tread surface when new by a bridge of rubber, the wavy grooves (6, 7) in the second direction being connected to at least one wavy groove (2, 4) in the first direction, - over at least a second axial part of the tread at least one wavy groove (1, 5) with waviness in the thickness of the tread and continuous in a third direction and a plurality of wavy grooves (6, 7) with waviness in the thickness of the tread and continuous in a fourth direction, each wavy groove comprising a plurality of open parts opening onto the tread surface when new and a plurality of closed parts, the closed parts being connected to the open parts, these open and closed parts being arranged in alternation, each closed part being spaced away from the tread surface by a bridge of rubber, the wavy grooves (6, 7) of this second axial tread part oriented in the fourth direction being connected to at least one wavy groove (1, 5) in the third direction, this tread being characterized in that: - when new, the open parts opening onto the tread surface of the first axial part are connected to one another to form a continuous surface network and in that the open parts opening onto the tread surface of the second axial part are disjointed from one another, - and in that beyond a part-wear condition, the open parts opening onto a new tread surface of the second axial part are connected to one another to form a continuous surface network and in that the open parts opening onto the new tread surface of the first axial part are disjointed from one another.