If all relationships with the ROUTE_ID property have a specific relationship type, say 'ROUTE', then you can do this:
START n=node(5), m=node(45)
MATCH p=shortestPath(n-[:ROUTE*..1000]->m)
RETURN p,length(p);
Otherwise, you can do this:
START n=node(5), m=node(45)
MATCH p=shortestPath(n-[r*..1000]->m)
WHERE all(x IN r WHERE has(x.ROUTE_ID))
RETURN p,length(p);
The former approach should be much faster.