Evaluation of the degree of deterioration by curvature had been investigated to make maintenance and management of the deck of road bridge. In the evaluation, the degree of deterioration was evaluated by Young's modulus aiming at the fact that the coefficients of the equation between Young's modulus and curvature can be represented by a simple curve. The results of the impact vibration test used as a simple test were evaluated by the curvature to check the soundness of the deck. It has become clear that the value of the Young's modulus is different from the obtained magnitude of the load is different It has been shown that rational optimization of the magnitude of the load is necessary.
