Don't think I've seen this posted, but with the shutdown of the line west of Swarthmore just two weeks away, here are links to the project website:
http://crumcreekviaduct.com/index.html
And to the webcams:
http://crumcreekviaduct.com/webcam.html
They are basically constructing the new bridge to the south of the existing one and will then slide it over once the existing structure has been removed.