Which of the following does NOT decrease a danger zone?

Heavy loads do not decrease a danger zone; in fact, they can increase the danger by affecting the handling and braking capabilities of the tractor-trailer. When a vehicle is loaded heavily, it can take longer to stop and may be more challenging to maneuver, which increases the risk in potentially hazardous situations.

In contrast, clear visibility helps drivers see obstacles and hazards well in advance, allowing them to react appropriately and safely navigate their environment. Proper signaling is crucial for communicating intentions to other road users, which enhances safety and reduces the likelihood of accidents. Increased speed can enlarge a danger zone since higher speeds reduce reaction time and increase stopping distances, making it harder for the driver to respond to changes in the driving environment swiftly. Therefore, heavy loads indeed contribute to a larger danger zone rather than reducing it.