Line 51 (Amsterdam Metro)

Line 51
Line 51
	A M7 series train coupled at Heemstedestraat
Overview
Native name	Metrolijn 51 / Ringlijn
Owner	Amsterdam Metro
Locale	Amsterdam
Termini	Amsterdam Centraal; Isolatorweg;
Stations	19
Color on map	Orange
Service
Type	Rapid transit
Operator(s)	GVB
Rolling stock	Serie S3 (2 cars); Serie M5 (6 cars); Serie M7 (3 cars)
History
Opened	1 December 1990; 33 years ago
Technical
Line length	18.7 km (11.6 mi)
Number of tracks	Double-track
Track gauge	1,435 mm (4 ft 8+1⁄2 in) standard gauge
Electrification	750 V DC (third rail)
Operating speed	70 km/h (45 mph)
Route map
Route map
	Legend
	This diagram: view; talk; edit;

Metro Line 51 (Dutch: Metrolijn 51), also known as the Ring Line (Ringlijn), is an Amsterdam Metro line running from Amsterdam Centraal station to Isolatorweg metro station, almost creating a full circle through Amsterdam. It was opened in December 1990 as a metro/tram hybrid line named sneltram ('express tram') and served the suburb of Amstelveen. Using special rolling stock, the Amstelveen Line ran as a metro on 750 V DC third rail from Amsterdam Centraal to the Amsterdam Zuid station, where it would switch operation modes and utilize 600 V DC overhead lines and end at Poortwachter. An extension to Westwijk was completed in 2004. In Amstelveen, the line partially ran on the same track as tram line 5 and had many level crossings.

The express tram was the result of a compromise between the municipalities of Amsterdam and Amstelveen. A full metro line for the suburb was proposed in the original 1968 plan of the system along with three other lines throughout the city, but the majority of these lines were cancelled due to protests against the demolition of houses caused by the metro construction in the city centre of Amsterdam. Amstelveen still wished to continue with the plans for a metro as it would not require any demolition, but the topic was too controversial in Amsterdam. The Amstelveen Line had problems following its opening as it suffered from a lack of capacity due to the lack of trains. It was temporarily shortened from Centraal to Zuid for 7 months in February 1991. Many collisions occurred at the level crossings, leading to additional safety measures.

Studies in the 2000s showed that Line 51 was unreliable due to the switching of operation modes, its level crossings and because it ran alongside a regular tram line. It was proposed to upgrade the section in Amstelveen to a full metro line as part of the new North–South Line, but this was deemed to be too expensive and was made impossible due to the developments at Zuid. In 2015, it was decided to convert the line into a high-quality and low-floor tram. Line 51 got its current route on the Ring Line as a full metro in March 2019 and was replaced by tram line 25 in Amstelveen.