The Department of Transportation manages much of the city's transportation infrastructure, including city streets, highways, sidewalks, and bridges. DOT is responsible for installing and maintaining street signs, traffic signals, and street lights, resurfacing streets, repairing potholes and other street defects, installing and maintaining parking meters, managing municipal parking facilities, and operating the Staten Island Ferry.

DOT supervises the city's franchise agreements with seven private bus companies, oversees private ferry operations on city-owned piers, manages the city's contracts with companies that provide transportation to pre-kindergarten special education children, issues parking permits to people with disabilities, not-for-profit agencies and governmental entities, and commercial vehicle permits for trucks, issues construction permits for work in city streets, and manages the city's Adopt-a-Highway program. DOT also promotes safe travel by bicyclists and pedestrians, and offers programs to foster traffic safety education.