ASLEF, the train drivers’ union, said that escalating violence on lines to the west of Glasgow has given rise to concerns that it is only a matter of time before a rail worker or a member of the public is seriously injured.
It warned that, unless the threats are removed, its members were “ready to refuse to work” the affected services.
The union has urged transport minister Humza Yousaf to take action to protect people travelling on trains westbound from Glasgow Queen Street station.
It said there had been a “continuous rise in violence and anti-social behaviour” on services to Helensburgh and Balloch and said it was “imperative” Mr Yousaf took “urgent action”.
The union said the government should ensure every train has at least two members of staff on board, bolster the presence of British Transport Police on trains and at stations in Helensburgh and Balloch and “back restraining orders” for repeat offenders.
Kevin Lindsay, ASLEF’s organiser in Scotland, said: “We believe it is imperative that the transport minister takes urgent action to ensure that passengers and rail staff are safe.
“Our members are at the end of their tether. There are real concerns that a member of the public, or a rail worker, is going to get seriously injured or worse.”
The routes highlighted by ASLEF have seen a spate of incidents this year.
This month, British Transport Police appealed for information after a woman was racially abused on a late night train between Helensburgh and Dumbarton. In March, a male passenger travelling from Anniesland to Helensburgh Central was assaulted on a train.
Mr Yousaf said: “Anti-social behaviour at rail stations and violence or the threat of violence against those using and working on public transport is wholly unacceptable. Every worker and passenger has the absolute right to go about their business without the fear of verbal or physical assault.
“We work closely with the police, Scotland’s transport providers and the trade unions to raise awareness of this issue and I have already committed my support in terms of the Violence Against Transport Workers campaign.”