It apears that ORS refuses to give driving directions on a road that has a gate on it (OSM tag barrier=gate), even if the gate has no access restrictions attached to it.
Here’s an example: directions from 45.32641,-121.66078 to 45.33181,-121.66399. This is the access road to a popular ski area. It has a gate which is almost never closed… but ORS refuses to route you past the gate if you’re driving a car. Walking and cycling directions work fine.
A lot of forest roads in this part of the world have open gates on them. They are included in OSM because they are landmarks, but they do not prevent access. I think ORS should ignore gates unless they have explicit restrictions.
That’s the intended way to deal with a barrier where the access rules are not defined.
If a barrier does not prevent access it can be stated with the access=yes tag.
For always open gates entrance can be considered as value as well (see wiki for barriers).
However, the workaround is rather useless and completely takes away all the benifits with a routing service, if I have to add all my via points manually.
If the user does not know that there is a barrier along the route, the user is guided another way and maybe thinks “oh well, maybe this detour IS the shortest way after all”.