At the eastern end of the Fullerton Transportation Center – the city’s Amtrak and Metrolink station – is Fullerton Junction. At this point, BNSF’s triple-track San Bernardino Sub reduces to just two mainlines, and two mainlines split off to become Metrolink’s Orange Sub, heading to Oceanside (where it then becomes San Diego Northern’s San Diego Sub to San Diego). As BNSF train S-LBELPC1-22, with ET44C4 3877 up front and ES44C4 8179 on the rear, passes through the Junction, it switches from Track 3 to Track 2, as here is where Track 3 becomes Metrolink’s Track 2. BNSF’s Track 2 splits here as well to become Metrolink Track 1. It’s like a math word problem! And there will be a test later… (Fullerton, California – February 24, 2021)