Around a quarter of the system has been used for urban rail transport since 1877, when the route between the city centre and Ouchy opened as Switzerland's first public funicular railway.

The line was however always nicknamed La Ficelle (literal translation: "The String") by its users due to its funicular past and circulation above ground in the greenery for more than half of its run.

The line serves an important purpose as it goes through the Lausanne campus, making it a crucial transport method for students accessing their university.

[9] An additional 2 kilometres (1.2 mi) of track is contained within the depot at Vennes, along with the signalling, security and information facilities.

This means that it is cheaper to operate[4] than a traditional system with drivers, and more flexible[dubious – discuss] during peak hours.

In contrast with line 1, trains also run on a totally separate right-of-way, meaning there is no conflict between the surface traffic and the metro, enhancing safety and reliability compared to a tramway.

All new sections of the route were built as double track, plus the reused Lausanne-Ouchy alignment was also rebuilt as double-track, with the exception of the tunnel under the CFF station due to high costs.

[12] The new vehicles, which are due to arrive in Lausanne by mid-2017,[12] are an interim solution to raise capacity on the central section of the line.

On 28 July 2008, a high-level manager for Alstom who had responsibility for the security system for the new lines was found hanging in the stairwell at the entrance to the Vennes station of the M2.

[13] The state has granted funds for major development of the Métro system, with plans in place for improvement work until 2025.

Capacity improvement is currently limited to the central and northern sections of the line, because the tunnel under the main railway station is only single-track.

[7] As of October 2019, a further public scrutiny project is underway, and work to build the new tunnel and platforms is due to start in 2022, with the new route expected to be operational in 2027.

[14] The end station Les Croisettes has been designed to allow a future extension of the line to the north[4] towards Epalinges-Village, or even Le Chalet-à-Gobet.

A Line M3 is proposed to serve the new development area of La Blécherette[15] and the west of Lausanne (Malley, Renens Bussigny).

[16] However, this issue has subsequently been clarified: while new platforms will be built at Lausanne Gare, a second tunnel will be constructed from there to Grancy, underneath the main railway station.

[19] In 2014, it was reported that the first stage of construction would be between Lausanne-Chauderon station, Lausanne-Gare and Ouchy, as a total of 47 million francs have been given to the project by the Federal Council.

[17] Public inquiries into the first construction project have now opened,[14] covering the initial stretch to reroute line 2 between Grancy and the current Lausanne-Gare platforms.