Improvements have been earmarked for Borders rail.
Recent complaints on capacity are set to be addressed in a Scotrail improvement package.
The Waverley line has suffered from overcrowding in recent months due to no extra carriages being put on in times of high demand.
Scotrail have planned a number of class 170 diesel trains to move over to the Borders line from the Edinburgh-Glasgow via Falkirk High route (to be replaced by electric class 380 trains), meaning an increased number of seats available to Borders passengers.
On weekdays 21 services will have more carriages (and therefore more seats).
On Saturdays, however 7 services are expected to have fewer carriages.
On Saturdays 28 services will have more carriages and 3 services will have fewer.
On Sundays 3 trains will have more carriages and 2 trains will have fewer carriages.
Last year Rachael Hamilton MSP raised the issue over of overcrowding on trains when major sporting events take place with the Transport Minister, Humza Yousaf. The Minister assured Mrs Hamilton the Scottish Government was doing its best to increase capacity.
The MSP for Ettrick, Roxburgh and Berwickshire also raised the issue with the First Minister, who agreed all Borders Passengers deserved a seat.
Rachael Hamilton MSP said: "I am pleased that Scotrail will make a number of improvements to the Borders Rail and help get every passenger a seat.
"It’s reassuring that Scotrail has listened to the criticism and will now work to put on more carriages and increase the number of seats.
"I will continue to keep an eye on Borders rail and fight for improvements to the line."
Alex Hynes, ScotRail Alliance managing director, said: “I was pleased to speak with Rachael Hamilton about the work we are doing to build on the success of the Borders Railway. From this week, the number of carriages on that route has significantly increased. This means there are more seats for customers, including during the busiest times.
“The Borders Railway has been a huge success, opening up a wealth of tourism and employment opportunities for the area. We will continue to work closely with local communities, businesses and others to support the vision of making the Borders a great place to visit, work, live and study. We are building the best railway Scotland has ever had - and that applies to the whole of Scotland."