No bicycle should ever be on a track, not only because of damage but its relative lack of maneuverability and takes up too much space.
Walkers should never be in any lane other than 8, and preferably outside lane 8. That has been the convention since forever. They should especially never walk side by side.
Lane 1 is not the "fast lane," for all the people indignant about that. If you haven't started using outer lanes for speed work, you should before you permanently screw up your biomechanics. If you're doing reps of more than one lap, you shouldn't be on the track any more than the walkers should, you should be out on the roads or paths.
Priority always goes to spikes, that's what the track was built for. Doing long repeats in trainers is like doing laps in scuba gear at a pool.