Flo and Blakset tunnels were to be built as two independent projects, but were merged into one. According to project manager Jon Harald Huseklepp in Vestland County Municipality, the Flo Tunnel was NOK 140 million cheaper than budgeted.

Interesting article. I am afraid it is in Norwegian but I think you should read it if you are in project management of tunnel construction.

https://www.bygg.no/slo-sammen-to-tunnelprosjekter-sparte-140-millioner/1497135!/