The public transport network may be significantly reduced, bus and rail fees increased, and free bus passes restricted to pensioners only, as Translink struggles to deal with growing demand and decreasing funding.
Public transport campaigner Eamonn McCann said the future of critical services in the North were at severe risk after the Department of Finance (DoF) and Translink issued stark warnings over the state of the public finances.
Mr. McCann said: "A fundamental policy rethink is necessary if we are to retain a viable public transport system even five years ahead.
"The axe on some services could fall within months. There is a particular threat to rural bus routes and rail."
In a budget briefing, which is out for consultation until January 26, the DoF said that across all Stormont departments additional budgetary pressures of £1 billion by 2018/19 have been projected.
One of the areas where cost pressures exist is public transport.
"Due to reduced subsidy for bus and rail services since 2014-15, Translink has maintained the public transport network by sustaining annual losses of around £13 million," the briefing states.
"These losses have been covered by
drawing on reserves but there is limited capacity for this to continue beyond the 2019-20 financial year.
"There would be a requirement to
significantly reduce the public transport network to ensure financial viability going forward. This would require a reduction in service levels," it adds.
Mr. McCann said this will result in cuts to bus routes, rail links and jobs.
"Translink is suffering a £10 million annual shortfall on buses, two million on rail. This could be covered if Translink were still able to avail of the fuel duty rebate it was entitled to until this was withdrawn in 2013/14.
"We now have the bizarre situation whereby large private companies in Britain are subsidised through the rebate - but the only publicly-owned network in the UK is starved of support.
"As a result Translink has to draw a higher proportion of its revenue from passengers’ fares than is the case in any region across the water.
"Translink has warned that the heaviest impact of service cuts would fall on 'commuters, young people, older people, people with a disability and those on low incomes'.
“There would also be a disproportionate impact on services in rural areas, where public transport provides a vital lifeline for many to access local amenities including healthcare," he said.
The Derry activist - a founder member of the Into The West lobby group - said public transport spending here lagged well behind that in Britain.
"Proportionately, our spending is less than half of Scotland’s. There is no rational reason for this. The development of rail has been disproportionately affected.
"Whether or not there’s a working Assembly, public opinion must be mobilised to save our essential services.
"We are calling on all political parties, trades unions representing rail and bus workers, passengers', environmental and other groups to raise their voices in opposition to cut-backs which will hit hardest at those who depend on public transport day in and day out.
"The cut-off point for feedback to the Department of Finance is January 26th. We urge members of the public to make their views clear, via firstname.lastname@example.org," he said.