SP in Chatsworth CA

Does anyone know why the SP chose the circuitous route they did to cross the Sta Susanna mountains thru Chatsworth. I grew up in Chatsworth in the 70's and of course by then the area was pretty developped. But I'm sure when they built this the area was sparse. I know the grade would have been important but it seems they could have had a more direct route. Look at the below link to a hybrid photo map of the area. You can clearly see the RR and it seems rather than building a second tunnel (between the 2 parks) they could have sloped down to the valley thru what is now Chatsworth Park South and continued fairly straight down to Lassen St. The rest of the line thru the valley takes the most direct route from NW to SE so what was happening in Chatsworth at the time of building that caused the circuitous routing? Any insight appreciated.

http://maps.yahoo.com/;_ylc=X3oDMTExNmI ... 6&q1=91311

The Southern Pacific coastline, from what I understand to be true, was built thru Chatsworth as a more direct line into the Los Angeles area.

Yes, but my question is why does it come out of the pass, curve north, then east, before heading south again. Looks like they could have accomplished a direct route from where they exit the pass and cut diagonally to cross the valley without this circuitous approach.