At hrs the road board is road only, you can't get off that board unless you loose your med cert, they can't bid jockey,or dock like some barns allow.
The local cartage board is one line seniority that includes dock, dock jockeys, linehaul jockeys, and city drivers, the local board is free to bid to any of those jobs he can hold and is qualified to do.
Now if someone on the road board loose their med card they can go to the local side but end tail in at the bottom of the seniority list.
If a qualified local employee wants to go to the road side he end tails in on their board but can't come back less he looses his med cert.