Train operator ScotRail is set to reach the end of the line when it changes hands at the weekend.
ScotRail has been shunted into the sidings in favour of FirstGroup
National Express will pass control of the franchise to transport giant FirstGroup early on Sunday morning.
An official launch, featuring the company's new look, will take place on Monday.
The new operator is called First ScotRail and is promising millions of pounds of investment and a boost in punctuality from 85% to 92%.
The company is promising a handful of early improvements followed in the next few years by a boost to stations, trains and services.
Investment of £7m is promised in an effort to tackle reliability problems and passengers are on track for 6,000 extra seats during the rush hour.
It's absolutely right that National Express has done pretty well for the Scottish rail travelling public
Rail Passengers' Committee
A major clean-up operation is under way on trains and stations, new customer information services are being provided, staff will wear freshly-designed uniforms and rolling stock, over time, will appear in new colours.
The service has received a subsidy of £1.9bn over seven years.
Rail union Aslef, which won a package worth a 22% increase from National Express, is poised to open a new round of pay talks with First ScotRail.
Bosses have promised a new service for Inverness commuters and another link which will cross Glasgow between Larkhall and Milngavie.
But Mike Lunan, of the Rail Passengers Committee for Scotland, warned: "Many of the improvements that have been put in the headlines are improvements that National Express was already in the throes of bringing into operation.
"FirstGroup has obviously put some of its own into that. But it's absolutely right that National Express has done pretty well for the Scottish rail travelling public."
He added: "After a rather hesitant start and one or two hiccups on the way - a big problem with the unions a couple of years ago which obviously held performance back - they've recovered extremely well."
The rail company's managing director Mary Dickson said: "First ScotRail has committed to invest £40m throughout the duration of the franchise in our stations
and various other improvements.
"We've also committed to improving performance - a year on year improvement of 2% on delays."
FirstGroup says it is keen to develop integrated travel. It will control up to 70% of bus and rail services across Scotland and 90% in Glasgow.
The Competition Commission has insisted on undertakings that the transport giant will not abuse its position.