The authority is this week expected to demand total control of fares, timetabling, rolling stock and service quality on ScotRail services after privatisation as part of its passenger service requirements for the franchise.
'What we are doing is trying to give effect to ministerial assurances that we wouldn't be financially disadvantaged by the Railways Act and that we wouldn't suffer loss of service,' said Charles Gordon, chair of the PTA.
He denied that the authority, which provides ScotRail with £112 million funding a year, was seeking to prevent privatisation or was playing political games.
He also said he would use Friday's special meeting of the authority to ask that the Office of Fair Trading examine at least five of the prequalifying companies for the ScotRail franchise. Any bids they made should be referred to the Monopolies and Mergers Commission on the strength of their local bus interests.
Merseyside has already presented potential bidders in its area with its service requirements.
The progress of the two passenger transport authorities is being watched keenly by the five other English rail authorities.
They have been called to a meeting with transport minister John Watts on 16 September to discuss franchising progress to date.
Andy Elmer, transport assistant secretary at the Association of Metropolitan Authorities, said the meeting was intended 'to determine the likelihood of there being significant amounts of franchising ahead of a general election'.
It is also expected to examine the funding implications of widespread franchising, in particular the need to set up a block grant system enabling PTAs to buy the rail services.