According to Enno Reinsalu (as published  on an Estonian Internet site - link below), Professor Emeritus of the Tallinn University of Technology (TUT) Mining Institute, the 57km long Gotthard railway tunnel is a prestige project.

In his opinion, whether to spend more than $12 billion to save an hour of driving time is a side question compared to project being a prestige one. He thinks 17 years is not a long time to build such a tunnel. As a rule of thumb, he says you should calculate extra one year for every 10 meters a tunnel depth. And for 200 meter depth, 17 years is OK.

He also says that any Gotthard tunnel experience will not be any useful when it comes to a future Gulf of Finland tunnel (FinEst between Helsinki and Tallinn) because in Gotthard, it was very hard rock and for the Finland and Estonia it would not be that hard.

https://majandus24.postimees.ee/3717253/ttu-emeriitprofessor-maailma-pikim-tunnel-on-eelkoige-prestiizirajatis