YouTube member azumatakeshi just posted two zenmen tenbou videos of the double-tracking project on the Tōbu Noda Line, now known as the Tōbu Urban Park Line:
Sakasai east to Mutsumi:
Umesato west to Shimizu-kōen, including construction of elevated tracks:
This is a pretty amazing and ambitious project, especially since much of the original right of way was designed for only a single track.