national rail passenger system, provides service to Atlanta via the Crescent train (New York–New Orleans), which stops at Peachtree Station. In 2014, the Atlanta Streetcar opened to the public. The streetcar's line, which is also known as the Downtown Loop, runs around the downtown tourist areas of Peachtree Center, Centennial Olympic Park, the Martin Luther King Jr. National Historical Park, and Sweet Auburn. The Atlanta Streetcar line is also being expanded on in the coming years to include a wider range of Atlanta's neighborhoods and important places of interest, with a total of over of track in the plan. Hartsfield–Jackson Atlanta International Airport is the world's busiest airport as measured by passenger traffic and aircraft traffic. The facility offers air service to over 150 U.S. destinations and more than 75 international destinations in 50 countries, with over 2,500 arrivals and departures daily. Delta Air Lines maintains its largest hub at the airport. Situated () south of downtown, the airport covers most of the land inside a wedge formed by Interstate 75, Interstate 85, and Interstate 285. Cycling is a growing mode of transportation in Atlanta, more than doubling since 2009, when it comprised 1.1% of all commutes (up from 0.3% in 2000). Although Atlanta's lack of bike lanes and hilly topography may deter many residents from cycling, the city's transportation plan calls for the construction of of bike lanes by 2020, with the BeltLine helping to achieve this goal. In 2012, Atlanta's first "bike track" was constructed on 10th Street in Midtown. The two lane bike track runs from Monroe Drive west to Charles Allen Drive, with connections to the Beltline and Piedmont Park. Starting in June 2016, Atlanta received a bike sharing program, known as Relay Bike Share, with 100 bikes in Downtown and Midtown, which expanded to 500 bikes at 65 stations as of April 2017. According to the 2016 American Community Survey (five-year average), 68.6% of working city of Atlanta residents commuted by driving alone, 7% carpooled, 10% used public transportation, and 4.6% walked. About 2.1% used all other forms of transportation, including taxi, bicycle, and motorcycle. About 7.6% worked at home. The city has also become one of a handful of "scooter capitals", where companies like Lime and Bird have gained a major foothold by placing electric scooters on street corners and byways. Emergency services The city is served by the Atlanta Police Department, which numbers