Network Rail has tabled a new pay offer to RMT, Unite and TSSA unions. Talks continue but I'm told "deal could be close".
Negotiations with ACAS went on until 21:00 last night and resumed at 09:00 this morning.
I'm told the offer amounts to a pay rise in "real terms" something the unions have been insisting on. The earlier four-year offer that was rejected amounted to a cash payment of £500 this year followed by rises in-line with RPI inflation.
But I'm told a proportion of future increases in pay will be dependant on unions agreeing changes to working practices - a "red line" for the company which views some of them as outdated and inefficient.
So, after three days of talks, common ground has suddenly loomed into view but agreement between the negotiating teams is not enough. Any deal would need to be signed-off by the unions' executives, the sovereign decision-making bodies.
The clock is ticking. One source described today as "the point of no return". At some stage Network Rail will have to start cancelling engineering work and communicating timetable changes.
It's crunch time but there's a feeling of peace in the air.