(a) The responsible person(s) designated in accordance with this section shall bear the legal and financial responsibility for making a key station accessible in the same proportion as determined under this section.

(b) In the case of a station more than fifty percent of which is owned by a public entity, the public entity is the responsible party.

(c) In the case of a station more than fifty percent of which is owned by a private entity the persons providing commuter or intercity rail service to the station are the responsible parties, in a proportion equal to the percentage of all passenger boardings at the station attributable to the service of each, over the entire period during which the station is made accessible.

(d) In the case of a station of which no entity owns more than fifty percent, the owners of the station (other than private entity owners) and persons providing intercity or commuter rail service to the station are the responsible persons.

(1) Half the responsibility for the station shall be assumed by the owner(s) of the station. The owners shall share this responsibility in proportion to their ownership interest in the station, over the period during which the station is made accessible.

(2) The person(s) providing commuter or intercity rail service to the station shall assume the other half of the responsibility. These persons shall share this responsibility. These persons shall share this responsibility for the station in a proportion equal to the percentage of all passenger boardings at the station attributable to the service of each, over the period during which the station is made accessible.

(e) Persons who must share responsibility for station accessibility under paragraphs (c) and (d) of this section may, by agreement, allocate their responsibility in a manner different from that provided in this section.