The city of Oakland is building a new elevated rail line to connect their BART station to the airport. It’s not a complicated line – like most airport shuttles, an unmanned train will simply shuttle back and forth every 5 minutes. I believe they’re using the cable technology common for the application.
Construction is moving along well, but this certainly caught my eye:
The connector will replace the Oakland AirBART buses, operated by the
Port of Oakland, that now take passengers to and from the airport using
local streets. Construction is expected to end late this year, and will
be followed by about a year of testing.