Hundreds of managers at Network Rail have been told that they are being made redundant as part of cost-cutting plans.
The 650 job losses - about 15% of the not-for-profit firm's management staff - were announced last month.
Managers were told during the morning who would lose their jobs by 31 December in a move criticised by union officials.
A spokesman for Network Rail said: "It was always known that there were going to be job losses, and those affected have now been told."
They continued: "A full redundancy package has been negotiated for each employee with counselling and work placement schemes in place to help ex-employees find new jobs and careers."
Those losing their jobs include contract managers, finance managers, signalling operations employees and station managers.
John Munday of the Transport Salaried Staffs Association, said: "The damage that this has done to company morale will have a long-lasting effect.
"This is a sad day for those who are leaving and a sad day for those who are left.
"Remaining staff will be forever looking over their shoulders wondering if they can trust this company again."
'Expensive consultants'
Network Rail is attempting to cut costs in order to increase the amount that can be spent on maintaining the rail network.
It has already announced plans to close its final salary pension scheme to new members to save money - another plan which has angered unions.
Mr Munday said shedding management posts could backfire on Network Rail in the future, especially given its recent decision to take control of all rail maintenance work.
"If Network Rail is looking to control costs it should not be sacking people now who it will have to re-employ as expensive consultants
later," he said.
"Morale among key managers is now at an all-time low, which is worrying at a time when the company is planning to take 18,000 employees from infrastructure and maintenance companies in-house."