Which mandatory element in a city's general plan is directly related to transportation matters?

The mandatory element in a city's general plan that is directly related to transportation matters is the circulation element. This element specifically addresses the movement of people and goods within a city, which encompasses various forms of transportation including roads, public transit systems, pedestrian pathways, and bicycle routes. The circulation element is crucial for ensuring that transportation systems are effectively integrated with the land use and development patterns of the city, ultimately enhancing mobility and accessibility for residents and visitors.

In contrast, while the land use element discusses the distribution of various types of land and how they can be utilized effectively, it does not specifically focus on transportation. The housing element is concerned with the availability and distribution of housing within the city, and the environment element addresses ecological considerations and sustainability. These elements are essential for comprehensive urban planning, but they do not directly pertain to transportation infrastructure and services like the circulation element does.