[6] Meanwhile, the section between Le Day and Croy on the Lausanne - Vallorbe line was doubled.

[7] As part of the plan to improve services on the RER Vaud network, it was decided to upgrade the line from Cossonay-Penthalaz to Vallorbe by renewing the signalling and, above all, moving the Day station 300 metres north of the old one.

Although the platforms for the new station were built in December 2021, they could not be used until 16 May 2022, when the new signalling system entered service[11] Since 7 August 2022, it has been possible to travel between Aigle and Vallée de Joux, via Lausanne, without changing trains.

The new railway station allows trains on the R4 line of RER Vaud to divide and serve Vallorbe and Vallée de Joux simultaneously every hour.

[12][13] As of the December 2024 timetable change,[update] the following services stop at Le Day:[14][15]