Network Rail chief executive Mark Carne visited Northamptonshire to see rail upgrades being made as part of a wider investment to deliver improved and more reliable services. 

One of the group's High Output Ballast Cleaners, which renews the crushed rock on which the tracks and sleepers are laid, has been working on rail lines between Euston, the West Midlands and the north. 

Potential track problems are expected to be reduced as a result of this work - and Mr Carne praised the machine as being among the most modern on the railway. 

"This work is part of a significant investment programme to deliver a better service to passengers on what is the busiest passenger and freight line in Europe," he commented. 

The machine is half a mile long and will continue to work overnight in the area, before moving onto the West Coast Main Line.