Observed trains at 11:15, 11:20, 11:28 on non electrified track.
Appears to be used only for frieght.
Alot of diesel fumes and noise when train passed tunnel.
Very little clearance when train passes.
Would be extremely dangerous if not in refuge when
Noted that tunnel becomes clear of fumes after 5 minutes
on breezy day.
11:42 entered tunnel.
Noted refuges every 30m.
Counted paces to know when next refuge would be.
Tunnel is 750 meters long.
Used torch to illuminate floor for safe footing.
12:00 exited tunnel.
Noted more trains at 12:00, 12:08, 12:16, 12:26.
Walked to Aachen.