A carrier device including a reinforcement arrangement (9) including: at least two adjacent reinforcement hollow portions (24, 25) both being traversed by the side wall (3) of the carrier device (2) and each made of an inner reinforcement hollow section (26, 27) of the inner reinforcement piece (14) and an outer reinforcement hollow (28, 29) section of the outer reinforcement piece (19), both reinforcement hollow sections being at least partially facing each other, and a longitudinal reinforcement fastening portion (30) located between the adjacent reinforcement hollow portions (24, 25), secured to the side wall (3), and made of an inner reinforcement fastening section (31) of the inner reinforcement piece (14) and an outer reinforcement fastening section (32) of the outer reinforcement piece (19), both reinforcement fastening sections (31, 32) being at least partially facing each other.