The tunnel scheme was briefly resuscitated in 1965 but was deferred once again in 1966.
Work was eventually resumed in 1974 and included the remodelling of the lower section of the deviation between De Doorns and Osplaas stations as well as the construction of tunnel no.
1, the twin tunnels.
This was completed in 1976, at which point financial constraints resulted in yet another postponement.
Authority to proceed was only given once again in late 1979.

The twin tunnels bored through a hill that was skirted around the western and northern sides by the original alignment to Osplaas.
When completed, the south-eastern of the twin tunnels became part of the new alignment of the De Doorns-Osplaas section.
The north-western of the twin tunnels was initially used for construction trains working on the rest of the tunnel system and became part of the new route when the tunnel system opened.
The south-eastern of the twin tunnels eventually fell into disuse along with the old Hex River Railpass.
The tunnel scheme was briefly resuscitated in 1965 but was deferred once again in 1966. Work was eventually resumed in 1974 and included the remodelling of the lower section of the deviation between De Doorns and Osplaas stations as well as the construction of tunnel no. 1, the twin tunnels. This was completed in 1976, at which point financial constraints resulted in yet another postponement. Authority to proceed was only given once again in late 1979.
The twin tunnels bored through a hill that was skirted around the western and northern sides by the original alignment to Osplaas. When completed, the south-eastern of the twin tunnels became part of the new alignment of the De Doorns-Osplaas section. The north-western of the twin tunnels was initially used for construction trains working on the rest of the tunnel system and became part of the new route when the tunnel system opened. The south-eastern of the twin tunnels eventually fell into disuse along with the old Hex River Railpass.
Hex River Tunnels