A complete rederivation of CRASH, with confirmation of its theoretical basis, elimination of many of its actual or supposed restrictions, and additions to its useful outputs. Furnished algorithms are readily user-programmed in handheld or desktop computers.In the trajectory solution, means for re-evaluation of the empirical spinout coefficients are furnished. In the impulse solution, the Common Velocity Check is eliminated so that more cases can be treated, and the coefficient of restitution is found from the impact data. In the damage solution, delta-V accuracy is improved by better fits to crash test data, better treatment of oblique impact, and inclusion the energy of restitution and inter-vehicular sliding. Yaw rates and impact forces are found from the impulse solution and again from the damage solution; these and other paired output comparisons indicate the quality of the reconstruction and facilitate its refinement.