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The Difference Between AOBRD & ELD: Mandates Explained


The recent legislation surrounding Hours of Service (HOS) reporting is causing some confusion. There are two key aspects to the ruling which are safety and compliance.  Trimble has provided a wide range of solutions to make drivers safe and compliant and many of our customers are asking what impact the new ruling will have on their business.   Although the compliance regulations are being rolled out in phases it is important to start the planning process now.

How did the mandate come about?

Every year, over 500,000 accidents occur on US roads. 5,500 of these result in fatality with 15% of drivers blaming driver fatigue for the accident. In response, the Department of Transportation developed new legislation which mandated that all driver’s hours of service be recorded electronically using an Electronic Logging Device (ELD) rather than the widespread paper logbooks.

What is in the mandate?

The legislation stipulates a number of rules that will affect commercial light vehicle operators, with the aim of ensuring their drivers adhere to safe driving practices. Relying on driver memory to complete logs and remember when to take a break will no longer be allowed. In fact, all US fleets with vehicles over 10,000lbs must start to electronically record HOS via Automatic On-Board Recording Devices (AOBRDs) or ELD by December 18, 2017, as per FMCSA 395.15.

AOBRDs are electronic devices that are able to record a driver’s duty status as required by FMCSA 385.15 since the 1980’s. The device must be linked to the vehicle to be able to report engine usage, road speed, miles driven as well as the time and date. An ELD is slightly different in that it must be capable of automatically recording driver time and HOS records. It can detect if the engine is running, whether the vehicle is moving, miles driven and offers accurate HOS, location information and driver identification in real-time. ELDs must be certified by the FMCSA as meeting their technical standards.



1988 AOBRD Rule

ELD Rule

Integral Synchronization

Required but not defined in the FMSCA rules.

Integral synchronization interfacing with the CMV engine electronic control module (ECM), to automatically capture engine power status, vehicle motion status, miles driven, engine hours. (CMVs older than model year 2000 exempted.)

Recording Location Information

Required at each change of duty status. Manual or Automated.

Requires automated entry at each change of duty status, at 60-minute intervals while CMV is in motion, at engine-on and engine-off instances, and at beginning and end of personal use and yard moves.

Graph Grid Display

Not required.

Must be able to present a graph grid of driver’s daily duty status changes either on a display or on a printout.

HOS Driver Advisory Messages

Not addressed.

HOS limit notifications are not required but “unassigned driving time/miles” warning must be provided on login.

Device “Default” Duty Status

Not addressed.

Status kicks in when the vehicle has not been in-motion for 5 consecutive minutes, and driver has not responded to a prompt within 1 minute.

Clock Time Drift

Not addressed.

ELD time must be synchronized to  UTC; absolute deviation must not exceed 10 minutes at any time.


It is important for organizations to understand the compliance regulations, as an example drivers must be able to immediately show information from the last 7 days on an AOBRD display when requested by a law enforcement officer. Failure to do so will result in large fines that can amount to $11,000 for some violations.


The legislation goes one step further. By December 16, 2019, all drivers subject to the rule must use certified and registered ELDs that comply with government regulations.