Longer trains and extra seats will be a boost for commuters travelling into London.
Work is underway to lengthen platforms at Haddenham and Thame Parkway and Princes Risborough stations.
Chiltern Railways chiefs say that longer platforms will allow nine-carriage trains to stop at the stations from summer 2015 following the opening of the Oxford to London Marylebone rail link.
The new route, additional trains and longer platforms will provide more seats for passengers on the increasingly busy route.
Rob Brighouse, managing director for Chiltern Railways, said: “As the number of passengers travelling by train on this route continues to rise, it’s important that we work together and invest in the network to meet the increasing demand.
“Longer platforms will allow longer trains to call at the stations, providing passengers with more space and more seats.
“The nature of the work means there will be some disruption while it is carried out but we continue to work closely with Chiltern Railways to minimise this as much as possible.”
The works will take place until Thursday 31 July either overnight or during weekend possessions which will mean amended services for passengers at certain times.
Information is available at www.nationalrailenquiries.co.uk or www.chilternrailways.co.uk.