Their drivers are often not used to the limited vision they have to the sides and rear of the truck. In winter, vehicles with frosted, ice covered, or snow covered windows are hazards. Vehicles may be partly hidden by blind intersections or alleys. If you only can see the rear or front end of a vehicle but not the driver, then he or she can't see you. Always be prepared to stop.
Delivery trucks can present a hazard.
The driver's vision is often blocked by packages, or vehicle doors. Drivers of step vans, postal vehicles, and local delivery vehicles often are in a hurry and may suddenly step out of their vehicle or drive their vehicle into the traffic lane. Parked vehicles can be hazards, when the people start to get out. Or, they may suddenly start up and drive into your way. Watch for movement inside the vehicle or movement of the vehicle itself that shows people are inside.