I have been paying extra to ride Acela because of the assigned seating. After almost a year of assigned seating many passengers still do not get it. I have, however, never had a problem when I tell someone that he/she is sitting in my seat and point to the assigned seat on his/her ticket. Conductors will usually help with this.Of course reserved seating only works if the reservation can be indicated somehow such as by a light, and other passengers and crew actually respect/enforce the reserved seat system. What happens when someone reserves from say PVD to PHL and someone getting on in Boston to ride to NYP sees the empty seat, ignores the light or whatever, does the crew enforce this, if they won't even deal with seat hogs?