is this a viable solution for chicken?

I think they look a bit cramped best to 'alert' @Lolimac or @Beckie76 they know about chickens.

 

The idea is fine needs some larger areas at the ends of the tunnels and in the middle. I assume you will be moving the tunnels to fresh grass every so often. The runs will need to recover chooks destroy grass quite quickly

 

they look quite happy out and about and they have lots of space , just the moving about which you will have to do looks awkward , novel idea and better than them being crammed in to a small pen which most people do.

 

Hi Java&me, your girls are gorgeous.
I like the idea of the chicken tunnel & because of its length your girls have plenty of room, I'm just wondering about the height maybe isn't tall enough, my girls like to flap their wings to do this they stand very tall & stick their wings out! Perhaps as AndreM said you could incorporate some larger areas to enable them to flap etc. I'd also give them an area where they could shelter in the rain, mine have a covered run, greenhouse & under my conifers to shelter from the wind/rain etc. the area in the tunnel is going to get scrapped about & will turn into mud! It will also get really smelly especially in the summer, you will need to move the run around. When I first got my girls I kept them on the grass but it got totally trashed & stank, both my coops are on my patio now it makes it easy to clean & disinfect with poultry shield so I don't get the smell! Your girls could also do with an area or box of dirt & sand so they can have a dustbath! I hope that helps you, hopefully @Lolimac will soon help you too, Loli has lots of experience too.
Do let me know if I can be of any further help & I shall look forward to hearing more about your hens xx

 

It's nice to see them out and about but as has been suggested some wider areas would be better for them .Should any of the girls have a tiff they haven't quite got the space to get out of the way of each other.I'd also make the 'tunnels' straight sided as I've known similar situations where their combs have rubbed against the sides and got sore.As Beckie has said they do like to stretch their wings too