This is clearly a Big Deal to the Niles Canyon Railway, as until now they've mainly only been able to run excursion trips that take you from A to A. Now they actually have a platform at the other end of the line, so you can ride from A to B, get off, do things, and come back again.
The Niles Canyon Railway is actually the last piece of the original transcontinental railroad. The railroad completed at Promontory Summit, Utah (not "Promontory Point") didn't reach the Bay Area until later, via an extension over Altamont Pass and Niles Canyon. This segment of the railroad (eventually part of Southern Pacific) was later abandoned and taken over by the railway preservation group.
Assuming I can drag myself out of bed that morning rather than sleeping in as I usually do, I hope to turn out for this event.