Think of it like a truck driver's built-in timecard and GPS trail rolled into one. The part that catches people off guard is this: after a semi crash, that data can disappear faster than most people expect if nobody sends a preservation letter right away.

An Electronic Logging Device or ELD is the system many commercial drivers must use under FMCSA rules to track driving time, on-duty time, rest breaks, vehicle movement, and engine hours. In a wreck on I-80, I-35, or a wind-blown stretch of highway near Des Moines or Council Bluffs, the ELD can help show whether the driver was pushing past hours-of-service limits, driving during a required rest period, or changing the log after the crash. That matters when the trucking company says the driver was alert, careful, and fully legal.

Practically, this is evidence you want locked down early. Ask your lawyer to demand the ELD data, backup logs, dispatch records, Qualcomm or telematics messages, and the truck's black box data before the carrier overwrites anything. In Iowa, fault fights get ugly because the state uses modified comparative fault under Iowa Code section 668.3. If the trucking company can pin 51% or more of the blame on the injured person, recovery can be barred. ELD records can help shut down excuses about speed, fatigue, delay pressure, or who was really making bad decisions before impact.