Link to the video of the UTC bridge work is at the bottom of the SANDAG story abpve.
Some browsing at SANDAG with "Del Mar" as a search term ... lots of stuff, but not much related to the railroad at the bluffs or the tunnel. There's some, though.
Several bluff stabilization projects. Here are links to some items that turn up on the first page.
Bluff Stabilization Project (2007): [
www.sandag.org]
Bluff Stabilization Project (more 2007): [
www.sandag.org]
Bluff Stabilization Project (2011-12): [
www.sandag.org]
Bluff Stabilization Project, some pictures (2017+): [
www.sandag.org]
Del Mar tunnels and other work - 2050 RTP project list (search for Del Mar - 4 hits in 2 project listings, one apparently preliminary work, the second the actual construction): [
www.sandag.org]