The problem of the impact of a mass on a beam of infinite extent is first examined within the context of Bernoulli-Euler beam theory and it is shown that this lead to an infinite deceleration of the mass at the moment of impact. This result arises from the fact that the simple beam theory predicts an infinite velocity for waves of vanishingly small wavelength. Thus the use of the Timoshenko beam equations which predict finite wave velocities may be expected to lead to more realistic results. It is shown that a finite value of teh initial; deceleration is obtained by using these equations. Certain conclusions of interest in the design of bean type highway guardrails are drawn from the results.