Don't do freight!! ... Rubber & Thumbs - ok... Exceptional training, required... Dogs can be trained to a variety of signals... Left & Right, Stop, Slow, Up, etc... Audio commands & leash training... As long as you're not trying to catch out with them & the dog is now showing sign of distress "travelling" itself should be fine... Dogs like humans can be extremely resilient.
... Railroads however, do damage their hearing... Blind & doesnt hear well - probably not a good combo... & limits your ability to see for them & communicate (audio commands) if they can't hear what you're asking them to do...
So, as stated above, depends on how you're planning on travelling. & how willing you guys are to work on/with training pup...
Blind dogs still make good herding dogs - because they're following commands of their masters & can hear what the herd does... If a blind dog can still be an outdoors working dog, personally, if they've got good owner, & arent doing rail travel, i see no reason blind dog wouldnt be just as good of a companion... If human & dog are properly trained.