"If there is any case for sustainable rail capacity investment Napier-north, Napier-Wairoa cargo opportunities are likely to comprise proportionately much more throughput than those from a Gisborne origin," Mr Bain wrote.
"In other words, Napier-Wairoa cargo opportunities may more readily meet return on investment criteria whereas the addition of Wairoa-Gisborne coverage may not."
Mr Bain said yesterday one factor that needed to be considered was that the cost of repairing the line was believed to be less significant on the Napier-Wairoa section than on the Wairoa to Gisborne section.
Alan Dick, the chairman of the council's regional transport committee, said he remained confident that re-opening the entire length of the line was viable.
Last week regional leaders met in Wairoa and agreed to support the regional council's proposal to secure a lease on the rail corridor.
A possible alternative option for the line - using it as a tourist cycle trail - also got up a head of steam last week when Havelock North man Malcolm Eves asked Parliament's Transport and Industrial Relations Committee to look into the possibility of funding a feasibility study into the idea.
The cycle trail feasibility investigation was pushed by National's Napier candidate Wayne Walford and Tukituki MP Craig Foss during the election campaign.