Snowplows have previously been mandated to require similar lighting to construction and public works vehicles, which included amber and blue strobe and rotator beacons and minor perimeter lighting. This resulted in trucks that were not as readily identifiable from other public works vehicles, and rear-end collisions on freeways and higher speed roads.
Quebec and Eastern Canada were updating their flashing arrow requirements for short and long term construction on public roads, which required the use of truck mounted and trailer mounted arrows with specific dimensional layouts. The new requirements involved the use of a round modular style layout while previously approved SWS traffic arrows use extruded aluminum housing with rectangular LED panels.
Traffic directors are usually a single long system comprised of 4 or more light elements that are “flashed” in a sequence as to convey the intent of the desired direction for traffic to divert. The issue is that they tended to be mounted high on the back of a vehicle to maximize visibility, but could block the center high mounted stop light (CHMSL or third brake light). Lowering the traffic director would minimize its effectiveness, so some users had to choose between having the CHMSL visible or maximizing the effectiveness of the traffic director.