Would it? Tunnels still require the same planning consents, particularly:And do people who aren't enthusiasts really care?
They care about getting to their destination quickly and with the minimum of fuss.
If it was all in a tunnel they would be closer to doing so as construction on Phase 1 would have started years ago.
-The impact of ventilation shafts/emergency tunnel access
-Tunnel construction/excavated material removal by road or rail