that seems to be unreasonably long. In germany, both the city I am studying at and the city I was born are undertaking big changes in their transportation infrastructure, and both don't take that long. In munich, building just started and is expected to last unit 2026 [1]. And we always complain that it's taking too long to plan and build!
40 years seems to be crazy! You would have to start repairing the old stuff when the whole project is finished.
Or are you talking about the whole process, including the financing? Then it's more understandable, many big project here also stall for 20 years until everyone has enough money and the political will to follow through. But I thought the financing is covered due to the sales-tax increase.
While it's easy to complain about projects not moving for 20 years, the sums are often quite enourmus and i am not sure whether inefficiencies are to blame, or whether gathering enough money just takes a long time.
[1] https://en.wikipedia.org/wiki/Trunk_line_2_(Munich_S-Bahn)