Dump trucks and aggregate haul units running out of a quarry yard spend much of their operating life under load in short cycles — loading, hauling a short distance, dumping, returning. That duty cycle stresses the engine and aftertreatment differently than steady highway running, but it does not change the legal inspection triggers or opacity limits. Duty cycle is relevant mainly to maintenance planning and vehicle readiness.
A heavy-duty diesel commercial motor vehicle with a Registered Gross Weight (RGW) over 4,500 kg needs an emissions test when it is being registered by a new owner and the vehicle is older than the current model year, or when it is at least seven model years old and the plate sticker is being renewed. Older aggregate and dump trucks remain in service, but the applicable inspection procedure must be confirmed for each vehicle using its model year and GVWR.
Many road-registered aggregate and dump trucks have an RGW above 4,500 kg, but the permit must be checked for each vehicle. RGW is the registered value on the permit — not a description of the load being hauled that day.
Ontario's DriveON program applies the SAE J1667 snap-acceleration (snap-idle) opacity procedure for heavy-duty diesel opacity testing, referenced under O.Reg. 169/22. The inspection is performed only by a licensed DriveON technician using approved equipment.
With the engine at normal operating temperature and idling, the throttle is opened fully while a light-extinction opacity meter records peak smoke density in the exhaust as a percentage. A pass means the vehicle is within its regulatory opacity limit at that time — not a full diagnostic of long-term DPF or SCR condition.
OBD is not a universal replacement for the opacity test. Eligible vehicles also receive an OBD system check or OBD data collection based on model year and GVWR under the current DriveON directive — including the 2007+ window up to 6,350 kg GVWR described on ontario.ca, and OBD data collection for newer heavier units where the directive requires it. Opacity still applies to qualifying heavy-duty diesels.
Before an authorized mobile DriveON visit, keep the unit accessible, at normal operating temperature when the technician is ready, and staged in a safe test location. Clear active faults that would block a valid inspection when possible. Related guides: Milton quarry & logistics hub and Hwy 401/25 industrial dispatch. Schedule through Piotr Service.
