A large number of existing reinforced concrete slab bridges are found to be insufficient for shear when calculated according to the governing codes. Seeking improved methods, for example, based on new experimental evidence, to assess the residual shear capacity and prolonging their service life can avoid large economic, environmental and social costs. Experimental results are combined with Monte Carlo simulations to quantify the increase in shear capacity in slabs as a result of transverse load redistribution. As a result, a larger number of slab bridges can remain in service.