What defines a cul-de-sac in urban planning?

A cul-de-sac is specifically defined as a street that is closed at one end, creating a dead-end that typically leads to a turnaround space. This design feature is prominent in residential areas and is intended to limit through traffic, thereby enhancing safety and reducing noise. It often encourages a more community-focused environment, as it discourages road traffic not related to local residents.

In contrast, a circular intersection refers to a type of junction where traffic flows around a central island, which does not describe a cul-de-sac, as there are multiple exits and traffic can continually circulate. A street with multiple exits indicates a more open road system that allows traffic to flow through, which opposes the function of a cul-de-sac. Lastly, a highway designed for through traffic serves to facilitate quick movement between longer distances, which is not applicable to the residential and localized nature of a cul-de-sac. Thus, the defining characteristic of a closed street at one end accurately reflects the functionality and purpose of a cul-de-sac in urban planning.