What would be the resultant CMF for two installed crash countermeasures with CMFs of 0.69 and 0.78?

To determine the resultant Crash Modification Factor (CMF) for multiple installed countermeasures, the correct approach is to multiply the CMFs of the individual countermeasures. This method reflects the way that each countermeasure impacts the risk of crashes independently. When combining their effects, rather than simply adding their values together, which could misrepresent the total impact, the multiplication accounts for the combined effectiveness of these safety measures, leading to a more accurate representation of how they work together.

Calculating the resultant CMF using the provided values of 0.69 and 0.78 through multiplication results in a product of 0.54. This signifies a reduction in the expected number of crashes, highlighting the cumulative benefit of implementing both countermeasures simultaneously. Thus, the correct approach acknowledges the multiplicative nature of risk reduction when evaluating the performance of multiple safety interventions.