X-ray vision courtesy of the PLPR train

Is it a bird? Is it a plane? No, it’s the super-powered Plain Line Pattern Recognition (PLPR) train, which ran on the Dartmoor Line in January 2021.

The PLPR train scans every clip, sleeper and component for defects, basically like an X-ray. It carries out a full check on track geometry. It performs laser scanning of ballast depths, profiles and takes a full video recording of the train path, all linked into GPS for real-time defect identification / location on site.

The train also tested the track for Top, Alignment, Twist and Dip angle faults. As would be expected for a mixture of railway components on an old line having been managed to different track standards, there were many faults to fix prior to allowing engineering trains to operate. These faults confirmed the importance of the planned renewal work and condition of the track. Network Rail had previously tested the track with static measurement systems, however the Track Recording Unit (TRU) provided greater safety assurance in the dynamic loading and assessment of the line for engineering trains to work on safely.

Behind the scenes to allow the train to run Network Rail had to gauge clear all the structures to ensure the train could safely pass on the line. This information needed to be approved by the route asset engineers who will eventually be responsible for managing the route. The TRU data is invaluable to the track maintainers as it helps them to understand the existing geometry, all of the assets on the line and generally having a clear line of site for future maintenance regimes prior to them taking on the responsibility of the line.

From a design point of view, Network Rail could understand the worst geometry locations to ‘design out’ poor track alignments to allow the designed line speed the project is aiming for and to really appreciate areas of poor formation where this isn’t so obvious through manual track inspections.

All this negates the need for many manual inspections. Thanks PLPR train!