Three years can pass quickly after a semi crash on I-75 near Flint, but the most useful evidence may be captured in the first few seconds before impact. An event data recorder is the electronic system in a vehicle that stores crash-related information such as speed, braking, throttle position, seat belt use, engine data, and sometimes sudden changes in motion. In a commercial truck, similar data may also come from the engine control module or other onboard systems.

After a wreck involving a big rig on I-94 in Detroit, US-131 near Grand Rapids, or the Mackinac Bridge in fog or ice, this data can help show what the truck and driver were doing right before the collision. It may confirm hard braking, speeding, failure to slow for traffic, or whether the truck kept moving without evasive action. That can support a claim against the driver, trucking company, or another party.

In Michigan, that matters because fault still affects recovery. The state uses modified comparative fault, and a person who is 51% or more at fault can be barred from recovering non-economic damages. In an auto case, Michigan's no-fault rules also limit lawsuits unless the injured person has a serious impairment of body function. Because recorder data can be lost, overwritten, or downloaded by the company, sending a preservation letter early can be critical.