That appears to be a Penrod I see in that tube. I always get big static zaps when I go in those tubes, especially the slides - I could probably light a 30 watt bulb for 10 seconds after I'm done sliding. But enough of my ramblings:
Nicely composed and well executed! I really like the idea and you've done well with it. To pick nits I would almost say a snooted light +1/3ev on her face/eyes to make it pop a little, but I would have to see the final result because it may just make her fade into the greys of the tube, tonally speaking. My nit aside I say this deserves a place on your wall :)
Next time you use the tube it might be interesting if you brought some chickens and have them looking in all the holes on the sides. Although chickens can sometimes be unruly ... and they are the dickens to direct.
This is a great image with a perfect crop. The only thing I would do to change it would be to either have the subject hold her head up to block out the busy background, or drape a white sheet at the end of the tunnel.