If the terminal/stations/stops can be put in the basement levels of buildings, the tunnels between stops might not need to be four lanes. This would need to be a long-term "vision" to ensure that provision was made in any new buildings along the corridor, especially if there are not below-ground car parking anywhere nearby.1NEEDS2POST wrote: ↑Tue Aug 30, 2022 11:24 pmAlso, your point about an underground O-Bahn interchange in Hindmarsh Square could be joined up with an underground bus tunnel, like in Brisbane. The O-Bahn tunnel was cheap (for a tunnel) at $160 million. A cut and cover bus tunnel under Grenfell and Currie Streets would be a bit more expensive because it would have to be four lanes (so you can have bus stops and other buses can pass). Probably much cheaper than a rail tunnel, the current tunnel entrance in Rymill Park can be returned to the parklands and with multiple entrance/exit ramps, a large number of bus routes could go through the tunnel.
If the plan was to only need the road corridor, then just about boundary to boundary would be needed, as there also needs to be space for the passengers to queue and clear the bus, not just have it pull over against the wall. The current bus stops use the footpath space, not just the road to the kerb.