Yesterday was the 60th birthday of the Squirrel Hill Tunnel, and to celebrate, Pittsburgh PBS affiliate WQED aired this special episode of
IT'S PITTSBURGH & A Lot Of Other Stuff. Some of the same pictures of the construction and dedication can be seen on my Interstate 376 (http://www.pahighways.com/interstates/I376.html) page.
Some more information and photos were featured in Post-Gazette's digs today:
http://pgdigs.tumblr.com/post/53919960487/june-1953-the-squirrel-hill-tunnel-opens-this