What is an ELD (electronic logging device)?
An ELD is the FMCSA-mandated device that automatically records a truck driver's hours of service (HOS) — replacing paper logbooks. It connects to the truck's engine, captures driving time, location, and engine status, and is required on virtually every commercial motor vehicle running interstate since the December 2017 mandate.
Before December 2017, drivers tracked HOS on paper logbooks — easy to falsify, hard to audit. The ELD mandate replaced paper with hardware that connects to the truck's engine control module and records drive time, on-duty time, and location automatically. The device displays the driver's HOS status to roadside inspectors via a single button or Bluetooth handoff to the inspector's tablet. Federal HOS rules limit a driver to 11 hours of driving in a 14-hour duty window after 10 consecutive hours off, with a 60-hour or 70-hour cap over 7 or 8 days. Once the ELD logs the driver into duty status, the clock runs whether the driver wants it to or not. The mandate created two structural shifts: (1) detention pay disputes got documented because the ELD records exact in/out times at every facility, and (2) the average loaded-miles-per-driver dropped by 3-7% because drivers can't fudge the logs to push past their limits. ELDs cost $150-$500 hardware plus $20-$40/month per truck for the software; most fleet ELDs are bundled with telematics (vehicle diagnostics, geofencing, IFTA mileage reporting, driver scorecards). Owner-operators and small fleets typically use lower-cost stand-alone ELDs that meet the FMCSA spec without the full telematics suite. Roadside ELD violations are out-of-service offenses — a driver caught without a working ELD parks the truck until it's repaired or a paper backup is approved.
- Who is required to use an ELD?Almost every commercial driver subject to federal HOS rules — interstate carriers running CMVs over 10,001 lbs, hauling 9+ passengers, or hauling placarded hazmat. Exemptions are narrow: drivers using paper logs no more than 8 days in any 30-day period, driveaway-towaway operators, pre-2000 model year engines (because they predate the engine control module the ELD connects to), and some short-haul drivers who stay within 150 air miles and return to base within 14 hours.
- How are HOS limits structured?Three primary limits for property-carrying drivers: 11 hours maximum driving time, 14 hours maximum duty window after 10 consecutive hours off, and either 60 hours in 7 days or 70 hours in 8 days (depending on the carrier's election). A 30-minute break is required after 8 cumulative hours of driving. The driver can split the 10-hour off-duty period into a 7+3 or 8+2 sleeper berth combination under certain conditions.
- What happens if a driver runs out of hours?They have to park immediately. ELDs lock out drive mode when the driver hits 11 driving hours, 14 duty hours, or the weekly cap — no override exists. Running past the limit shows up as a violation on the next roadside inspection or on the carrier's CSA score. Brokers and shippers near 'no parking' deliveries (urban DCs, no truck-friendly facilities) sometimes face avoidable detention because the driver has to find legal parking before the clock runs out.