I live about half a mile from the Oceanside - Escondido branch, home to the Sprinter light rail service and a tri-weekly freight train.
The Sprinter service uses Siemens VT642 Desiro diesel railcars. They mostly run as single sets, except during rush hour when the trains are made up of two units.
I think the freight trains are mostly run by some company called Pacific Sun or something. They use older geeps for that.
I'm not sure how often BNSF actually runs trains along the branch.
About 20 miles west of here is where the branch starts, Oceanside. It's a busy station, serving as NCTD's Sprinter's western terminus, NCTD's Coaster's northern terminus, Metrolink's southern terminus, and a through stop for Amtrak's Pacific Surfliner. The Coaster, Surfliner, and Metrolink own F59PHI's. Coaster owns mostly F40PHM-2C's, Metrolink has mostly F59PH's, and the occasional P42DC heads up the Surfliners, along with an F40PH NPCU on the end of the extra single-level Surfliner set made up of Amfleets and Horizons.
At night, after the passenger trains stop running, several BNSF frieght trains take advantage of the open tracks to run north and south through the station.
I'll find some pics to post when I've got the time.
EDIT (finally):
Here's a southbound (loco facing north) Coaster train awaiting its departure on track one next to a northbound (loco facing south) Metrolink train on track two. The Metrolink's cab car is one of their nifty new Hyundai-Rotem "Guardian" fleet cars. This pic might be slightly dated, since most Metrolink trains now have less Bombardier bi-levels in use.
Here's a Sprinter train waiting at its own separate stub-end light rail platforms, while a Coaster sits at the through tracks maybe twenty feet away. The little Sprinter trains are scheduled to meet NCTD's Coaster trains for fast and easy transfers between them, along with many of the Surfliners.
A Sprinter train its own dedicated elevated loop line in San Marcos, either heading for or away from the California State University San Marcos station.
Inside the Sprinter maintenance facility in Escondido: