How much of all fatal crashes occur on roads with what speed limit?

The assertion that half of all fatal crashes occur on roads with a speed limit of 55 mph or more is based on traffic safety statistics that indicate higher speeds increase the severity of crashes. Roads posted with speed limits of 55 mph or more often accommodate faster-moving vehicles, which can lead to a greater likelihood of crash incidence due to reduced reaction times and increased stopping distances.

Research has shown that the risk of fatalities in motor vehicle crashes rises significantly with higher speeds. This is due to the increased kinetic energy involved in collisions, which results in more severe impacts. Furthermore, driver behavior tends to differ at higher speeds, often leading to more aggressive driving and less margin for error.

Hence, the correct answer highlights a critical insight into the relationship between speed limits and the occurrence of fatal traffic incidents, emphasizing the importance of adhering to posted limits, especially on higher-speed roadways.