In a recent collaboration with Martin Zero, we filmed the full course of the tunnel..

Overview from https://archaeologytea.wordpress.com/

Excavations outside the entrance of the second, eastern, tunnel revealed an in situ length of iron tramway track 2ft 4in wide and 5.40m long adjacent to an area of cobbles. Most of the south half of the trench was taken up by these tramway tracks. These were represented by two parallel sets of wrought iron rails which ran west to east for 5.40m. Each line comprised two rails.  click here for more images and clips