 In 1940 the section in the neighbourhood of Fuorigrotta was reconstructed and put underground, with the new stations of "Fuorigrotta" and "Mostra" built in rational architecture style.In the same year the SFN give the line to the SEPSA, a branch of the EAV.In 1962 the electrification was elevated from 1,2 to 3 kV, and the new ET 100 EMUs were put into service.