What area is in? Is it remote or in a more developed area? I would think that it would be on some historic preservation list.
This is in the English Midlands in a quiet rural area with a low population density. However, there are fairly large towns about 8 miles north and south and this is a popular footpath and cycle track connecting them. I hardly saw anybody when I was there 10 or so years ago, but there are more people about now, especially at weekends.
I ran into the side of the tunnel while riding through a particularly dark section. Humans have little to no proximity sense in the dark. I ended up with a scraped right arm.
I'm glad it's not just me who has trouble keeping my balance in this situation. I thought being able to see daylight at the end of the tunnel would serve as a reference point, but it didn't. It was too small and too distant.
Tony