New Measurement Trains
What is it
The New Measurement Train (NMT) is Network Rail’s flagship high‑speed infrastructure monitoring train, a converted InterCity 125 High Speed Train used to assess track and related assets on the main line network. It consists of two Class 43 power cars and typically five or six Mark 3 coaches re‑equipped internally with measurement, processing and staff facilities. Affectionately known as the ‘Flying Banana’ because of its yellow livery, it is part of the wider ‘yellow fleet’ of specialist monitoring trains.
Why it matters
The NMT enables high‑speed, repeatable measurement of track geometry and other parameters at up to 125 mph, using sensors including AIVR FFV cameras. This allows inspection to be carried out in traffic without taking possessions. The data captured by the NMT supports early fault detection, reduces the risk of derailments and underpins condition‑based maintenance and renewals planning while saving Network Rail millions of pounds in avoided unnecessary work.
Strengths include very high route mileage (around 115,000 miles a year), coverage of around 4,800 miles every two weeks and integrated systems for geometry, PLPR, OLE and GSM‑R, giving a rich multi‑modal dataset along the same run. Weaknesses include dependence on a limited number of high‑value train paths, focus on plain line rather than all complex assets, and ageing high speed train (HST)‑based vehicles that require specialist maintenance and eventual replacement.
When it operates
The NMT entered service in 2003, following conversion of HST vehicles for dedicated measurement duties. It has been in continuous use since then.
It typically works on a four‑weekly cycle, surveying most main lines and some secondary routes within each cycle, an increase in frequency from earlier 13‑week patterns after PLPR deployment. Atypical operation includes special runs for new or upgraded infrastructure (e.g. ETCS or OLE projects) and occasional timetable changes during industrial action or major blockades, when paths may be compressed, diverted or deferred.
Where it operates
The NMT operates across Britain’s principal Network Rail‑managed routes, including the West Coast, East Coast and Great Western main lines, plus selected secondary and diversionary routes. It is diagrammed to maximise coverage of the circa 20,000 route‑miles of Network Rail infrastructure, with stabling and maintenance centred at the Railway Technical Centre, Derby.
On electrified routes such as the West Coast Main Line, particular emphasis is placed on monitoring OLE clearances and geometry for tilting and high‑speed stock. Non‑electrified and mixed‑traffic routes are covered primarily for geometry, rail surface and visual asset condition using the same consist.
How it works
Core systems include a track geometry measurement system using lasers, LVDTs, gyroscopes and accelerometers to derive gauge, alignment, twist and cant at line speed. Complementary devices include laser track scanners, longitudinal level sensors, a roof‑mounted OLE height and stagger measurement system, GSM‑R radio survey equipment, and Plain Line Pattern Recognition (PLPR) cameras that generate long, high‑resolution image strips for automated defect recognition.
Data from these devices is processed on board in dedicated development and production coaches, then transferred to Network Rail back‑office systems where engineers review exceptions, validate algorithm outputs and integrate results into maintenance planning tools. Geometry, PLPR and ancillary data are shared via central databases and decision‑support systems, allowing route asset managers, maintenance delivery units and project teams to access consistent condition information for their sections of railway.