Abstract: Tunnel liner plate assembly comprising a tunnel liner plate comprising an outer wall and inwardly extending side and end flanges, each having bolt holes therein, and a longitudinally extending plate metal reinforcement extending from end flange to the other and comprising a center section which abuts the outer wall of the liner plate, a pair of upstanding side section which are integrally joined to the center section along respective side edges, and laterally projecting flanges which project laterally from the upper (or inward) edges of the respective side sections. The center section and the side sections together provide a U-shaped configuration and the laterally projecting flanges, which are spaced from the outer plate of the outer wall of the tunnel liner plate and are parallel thereto, afford a marked increase in moment of inertia and section modulus with very little increase in mass.