What is prohibited when parking on a bridge?

Parking on a bridge is prohibited at any time primarily due to safety concerns. Bridges are designed to allow for the efficient flow of traffic, and any parked vehicle can create significant hazards. They may obstruct the view for other drivers, increase the risk of accidents, and hinder emergency response vehicles if needed. Additionally, parking on a bridge could create structural stress and potential damage to the bridge itself.

The other options do not reflect the safety regulations regarding bridge parking accurately. There are no specific time restrictions such as weekends, duration limits like over an hour, or night hour prohibitions that would apply instead of the outright ban on parking on bridges. Hence, the correct answer emphasizes the need for maintaining clear and safe travel routes over these critical infrastructure elements.