Actually, very recently I stumbled upon quite a few of these tracks in google. Los Angeles has a lot of odd shaped warehouses that are curved on the end. Not to hard to see that they all used to be spur lines.
http://g.co/maps/dj56y
The lines disregard the grid.
http://g.co/maps/dwjye
http://g.co/maps/99b4q
You can even see that they're using those same lines to build the new light rail lines on the same pathway (note the parallel cracks in the pavement).
http://g.co/maps/6sfcf