Akka Technologies is developing pods with detachable wings that would integrate aviation and public transit. The AKKA Group is an engineering and technology consulting company with 16000 employees.
The detachable wings would make for vastly more efficient boarding and improve the utilization of the engines and wings.
You go to a local train station and board the train-like tube. This pod takes you straight to the airport. The pod then moves onto the runway where a cockpit and wings are attached to the passenger train before taking off. Upon landing, the fuselage detaches from the wings and rolls out of the airport to local train stations to drop you at a convenient location.