What is the purpose of a no entry sign?

A no entry sign serves to clearly indicate that entry into a particular area is prohibited. This sign is often found at the entrances of roads or zones where traffic should not enter for safety reasons, such as in one-way street situations where entering from the wrong direction could create dangerous conditions. The purpose is to prevent vehicles from mistakenly entering an area that could lead to accidents or confusion.

The other options address different traffic situations. Signals for one-way streets guide drivers on the correct flow of traffic but do not inherently prohibit entry. Parking signs provide instructions and regulations regarding where a vehicle can legally stop and park, which is unrelated to entry restrictions. Road hazard signs warn drivers about potential dangers ahead, but they do not indicate access permissions. Therefore, the no entry sign specifically fulfills the role of prohibiting access to certain areas, making it crucial for maintaining roadway safety and order.