You can do what I do and go to this thread and download your favorite version of RiB as an mp3/ringtone. Then you can play it on your phone's speaker as you make your way through the tunnel.

It's a bummer if it's truly gone. I always really liked the Eno-esque version in the Tunnel of Tomorrow and the sound of it always got me excited to fly, usually because all my big fun European flights left from C.