Thanks Shona. It is a fascinating question. Curiosity got the better of me this evening & I found this item from the Waze / Google folk. https://www.gislounge.com/connecting-gps-tunnels/
I mentioned to Bernice some time ago that it would be great to have this similar technology for underground car parks or multi-level shopping centre carparks.
Expanded to tunnels, where there are multiple exit points, I would think the Waze technology or developer of similar technologies would find a potentially large market globally. It would be a gold mine for a tech nerd entrepreneur or similar company. It’s something that Here should or could be thinking about for the future.
In a city like Sydney where it is now too expensive to acquire property to widen many roads, we have seen in recent years that the government is building more road & rail infrastructure underground. For underground roads, the GPS Navigation technology needs to adapt to keep commuters on the right path through tunnels.
Yes I’m aware of the mobile phone repeaters or transmitter nodes in the Sydney train tunnels & also FM radio stations are repeated in the harbour tunnel by a technology known as leaky coax cable for vehicle reception in the tunnel. The required technology for GPS in tunnels is entirely different.
My eyes are really straining with this faint small font………..