I only took the SL2 route, from Boston’s Black Falcon cruise terminal to South Station, and that branch doesn’t use the Ted Williams tunnel, and only makes a few stops on surface streets.
I found its operation fascinating. The Neoplan Dual Mode articulated bus ran like any other bus on the street, with the operator collecting fares as passengers all boarded thru the front door.
When the bus pulled into the”Silver Line Way”, the HVAC blowers shut off, then the engine shut down, then the blowers started back up, and the bus quietly started forward, now powered by its trolley poles which had raised at the stop.
It then entered a gate-protected ramp down into a tunnel, and then made its remaining stops in subway-like stations . The driver opened all three doors for passenger entry and exit, as the stations used fare control access to the platforms.
Arriving at South Station gave free access to all connecting subway lined.
