The Scotsman understands there is a new willingness to look again at the plans amid concern the merger process could take years to get right.
Rail unions and staff associations have repeatedly called on the Scottish Government to scrap the integration, which would see the BTP’s operations north of the Border taken over by Police Scotland.
Earlier this year, a planned start date of April 2019 was postponed amid concerns over unresolved issues around the integration of IT systems and how the terms and conditions of officers transferring from BTP to Police Scotland will be protected.
A re-planning exercise is currently being carried out, and it was thought a new start date would be announced later this month.
However, a Scottish Government source said there was a new desire to “look at other options”. Insiders believe the merger is set to be scrapped.
Any alternative model would need to be accountable to both the Scottish Parliament and the Scottish Police Authority (SPA).
In February, Police Scotland said it had become clear the integration would not be achieved by next April without “compromising public safety”.
The national force is due to assume responsibility for railway policing under legislation passed last year by the Scottish Parliament, despite concerns from the railway industry, staff associations and trade unions.
But just last week a report prepared for the SPA warned that Police Scotland may not currently have the “capacity and capability” to absorb the work of the BTP. The devolution of railway policing was one of the recommendations of the Smith Commission, published in 2014.
However, the parties at Holyrood have been split on the best model to take forward, with rail unions accusing the SNP of putting “nationalist dogma” above public safety by seeking to replace BTP with Police Scotland.
Dr Kath Murray, a policing researcher at Edinburgh University, said looking at other options was the right thing to do.
She said: “Against a backdrop of major challenges, escalating costs and deep-rooted opposition, any move to consider alternative devolution options will be widely welcomed.
“A commissioned service model or similar could strengthen accountability, improve access to Police Scotland resources and retain existing specialist skills, without any of the operational or financial risks associated with full integration.”
Details of the plans emerged as pressure was put on Police Scotland’s new chief constable to call a halt to the merger.
Iain Livingstone, whose appointment was announced earlier this week, updated the Scottish Parliament earlier this year on the difficulties facing the project.
Yesterday, Manuel Cortes, general secretary of the TSSA union, said the merger process was “unworkable”.
He said: “This is a burden no incoming chief constable – or chief executive – would want. An unworkable and unnecessary merger which has been forced on the police forces against their own advice for purely political reasons.
“Nothing about this merger is straightforward.
“Over a year since the act was pushed through in Holyrood and the two forces haven’t been able to agree arrangements for IT, pensions, career development or terms and conditions after the merger.
“And if Livingstone does manage to square the circle and get the merger to go through he will face an unprecedented staffing crisis as a third of staff and officers are planning to leave BTP in the event of it becoming part of Police Scotland.”
He added: “Rail passengers and staff need to know their safety is assured.
“The merger has already experienced severe delays, time to put us all out of our misery and cancel it altogether.”
There are around 220 officers working for BTP in Scotland, with previous research suggesting many could leave rather than join Police Scotland.
Its operations in Scotland cost the rail industry £22 million in 2017/18.
The Scottish Conservatives’ shadow justice secretary, Liam Kerr, said: “There is concern right across the board about the prospect of this ill-judged merger.
“Iain Livingstone could use his newfound influence to ensure these plans are dropped.
“That way the SNP ministers could save face by not U-turning on their own ridiculous proposals.
“Iain Livingstone will have enough challenges without these new responsibilities. This is the perfect opportunity for this merger to be scrapped altogether.”
A Scottish Government spokesman said: “Devolution of BTP was recommended by the Smith Commission, reached through cross-party agreement, and integration will also ensure railway policing is fully accountable to the Scottish Parliament.
“There is a re-planning exercise currently taking place. Once that is completed, we will ensure parliament is updated on our next steps. We will never compromise the safety of the public.”