Question: The Coast to Vines rail trail open to pedestrians and cyclists, runs for how many km through the southern suburbs of Adelaide from Marino to Willunga, a town south of Adelaide, South Australia in the City of Onkaparinga local government area 47 km from the Adelaide CBD?

Context paragraphs:
Willunga railway line: The Willunga railway line ran through the southern Adelaide suburbs from Adelaide railway station to Willunga, over 45 km long (longer than the current Gawler line, 42.2 km ).  The line was opened in Willunga by the Governor of South Australia Sir Henry Galway on 20 January 1915, and initially had 16 stopping places between Adelaide and Willunga.  It closed beyond Hallett Cove in 1969 and was dismantled in 1972.  The Seaford railway line continues from Hallett Cove along a different alignment before rejoining the route of the old line between Seaford Road and Griffiths Drive.

City of Onkaparinga: The City of Onkaparinga is a local government area (LGA) located on the southern fringe of Adelaide, South Australia.  It is named after the Onkaparinga River, whose name comes from "Ngangkiparinga", a Kaurna word meaning women's river.  It is the largest LGA in South Australia, with an estimated population of 164,800 people in both urban and rural communities and is also geographically expansive, encompassing an area of 518.3 km².  The council is headquartered in the Noarlunga Centre with area offices situated in Aberfoyle Park, Woodcroft and Willunga.

City of Playford: The City of Playford is a local government area of South Australia in Adelaide's northern suburbs.  The name 'Playford' comes from the recognition of Sir Thomas Playford, who played a part in the development of the area, and was South Australia's premier from 1938-1965.  The City covers an area of 346 km, and is home to approximately 88,000 residents.  Playford is the fastest growing local government area in South Australia.  s of 2016 the city motto is: "a great place to live, work and play".

Willunga South, South Australia: Willunga South is a town south of Adelaide, South Australia in the City of Onkaparinga local government area.  Willunga South is established in the Sellicks Hill Range and is located at the base of Delabole Hill.  It is 6 km south of the wine growing region of McLaren Vale and is approximately 48 km from the Adelaide CBD.

Patrick Jonker Veloway: The Patrick Jonker Veloway (formerly known as the Adelaide Southern Veloway) is a sealed bikeway for the exclusive use of cyclists that runs continuously alongside the Southern Expressway for a distance of 7 km — from Marion/Main South Road to the Panalatinga Tunnel.  South of the Panalatinga Tunnel, the bikeway becomes a shared track for the remaining 12 km of the Southern Expressway.  It provides important links to other cycling facilities in the area, notably the Sturt River recreational trail at the Veloway's northern end, and the Coast to Vines rail trail at both Panalatinga Road and Southern end of the shared track.  The Northern end of veloway links to the Sturt River shared path, providing an almost non-stop bicycle route between Glenelg and Willunga.

Marino Rocks Greenway: The Marino Rocks Greenway is a 15 km cycling route in Adelaide, South Australia.  It follows the Seaford railway line from the southwestern corner of the Adelaide city centre to Marino Rocks railway station.  The route leads into the Coast to Vines Rail Trail which continues along the alignment of the former Willunga railway line.

Coast to Vines Rail Trail: The Coast to Vines rail trail open to pedestrians and cyclists, runs for 34 km through the southern suburbs of Adelaide from Marino to Willunga.  Much of the trail has been constructed on the disused Willunga railway line.

Capital City Trail: The Capital City Trail is a shared use path for cyclists and pedestrians, which circles the Melbourne city centre and some inner eastern and northern suburbs of Melbourne, Victoria, Australia.  It is 29km in length, and mostly consists of sections of other trails, such as the Merri Creek Trail, Main Yarra Trail, Moonee Ponds Creek Trail and Inner Circle Rail Trail.

Willunga, South Australia: Willunga is a town south of Adelaide, South Australia in the City of Onkaparinga local government area 47 km from the Adelaide CBD.  Sometimes considered a part of the Adelaide metropolitan area, it is located within the famous McLaren Vale wine growing region.  At the 2011 census , Willunga had a population of 2,416.

Moana, South Australia: Moana is an outer coastal suburb in the south of Adelaide, South Australia.  The suburb is approximately 36.4 km from the Adelaide city centre.  It lies within the City of Onkaparinga local government area, and neighbours the suburbs Seaford, Maslin Beach, Seaford Rise and Port Noarlunga

Supporting paragraphs: Coast to Vines Rail Trail Willunga, South Australia
Answer: 34