Nice tunnels folks, but my favorite is the Paw Paw Tunnel on the C&O canal towpath trail. It's 3118 feet long, without lights and you share it with the canal. You have to stay on a narrow path alongone side of the tunnel. Most people walk their bikes through it, it can be ridden.
It's along a very scenic trail that runs 185 miles between Cumberland MD and Washington DC.
I can't seem to attach any pictures, but it's worth the journey