Network Rail managers will step in today to keep services running on the Wolverhampton to Shrewsbury line following a walkout by signalmen.
Members of the RMT union are protesting at what they say are unsafe manning levels at the Madely signal box. An RMT official warned last night that the dispute could escalate into an all-out strike across the region.
The union is balloting for industrial action among its members at all signal boxes in the West Midlands.
The result of the ballot will be announced on November 30.
RMT West Midlands spokesman Ken Usher said he was confident members would vote to strike and he warned of "total disruption" in the run-up to Christmas.
The dispute is over new computer-based systems at signal boxes. Mr Usher said Network Rail had cut staffing at the Madely box to one, which would make it impossible to take a VDU screen break every 20 minutes.
Mr Usher said: "We have asked for an extra man but Network Rail have imposed rosters. Other signal boxes operating this system have double manning but management in the West Midlands have decided to introduce single manning.
"This is nothing about wanting extra money. We see this as a safety issue."
Today's 24-hour strike will begin at noon.
A Network Rail spokeswoman said: "There are some local issues at Madely signal box which we are trying to resolve. The good news for passengers is that services will not be affected. The signal box will be fully operational and operated by experienced, competent Network Rail managers."