We enjoy rail trails including the WOW and the connected trail section in Belmont. We would like the see the expansion but not at the expense of existing rail use.
There is one example of mixed rail and trail use: the Cotton Valley Rail Trail in Wolfeboro.
https://www.conwaydailysun.com/outdo...53054b50c.html
http://www.cottonvalley.org/index.php
In this case the rail use is limited to small private rail cars. As both types of users support maintenance of the rail trail it appears to be a peaceful cooperative coexistence.
Walkers and bicyclers at times have to go between the rails which in these spots is filled in with packed gravel. In the winter most of the trail is open to snowmobiles and there are connections with state corridors.