A system for automatically detecting an operational event for a bulk material hauler vehicle. The system includes a sensor mounted on the bulk material hauler vehicle, which is adapted for hauling a bulk material such as an aggregate. The system further includes a telematics system provided on the bulk material hauler vehicle. The telematics system includes a processor running software (or executing instructions or code) for detecting the operational event (e.g., providing functions of a load and unload detection module or discriminator as described herein). During vehicle operations, the sensor transmits sensor data to the telematics system, and the detecting of the operational event includes retrieving a signature definition for the operational event and then verifying the sensor data meets requirements of the signature definition. In some embodiments of the system, the operational event is loading the bulk material on or unloading the bulk material from the vehicle.