The sign you mentioned, "other or multiple multi-track vehicles" (1049-12), indicates that drivers should expect a mixed traffic situation where various types of multi-track vehicles, such as buses, trucks, and trailers, may be present. This sign is typically placed in areas where there is a significant presence of larger vehicles on the road.

In practical terms, when you see this sign, you should be especially vigilant and cautious. Pay attention to your surroundings, particularly when changing lanes or making turns, as these larger vehicles often have different handling characteristics and may require more space to maneuver.

Also, be aware that these vehicles might obstruct your view of other road users, and give them the right of way when appropriate, especially at intersections or in tight spaces. Always ensure you are maintaining a safe distance from these vehicles to avoid potential hazards.