A Fact Sheet on RailMeasurement Ltd's RCA is available here.

RCA mounted under caboose of a reprofiling train. Alternative arrangements are possible, including direct mounting to bogie. Typical measuring speed of 3-15km/h.

RailMeasurement’s RCA (Rail Corrugation Analyser) is widely used to to monitor the results of reprofiling and to assess reprofiling requirements.  Several different designs of the equipment have been supplied to fit onto bogies, to small metro grinding trains, to hi-rail vehicles and as a self-contained measuring trolley.  Varieties of the RCA have been supplied to measure microns on a rail over the full speed range 0.5-50km/h at which milling trains, grinding trains, and hi-rail inspection vehicles operate.


The RCA provides accurate measurements of the longitudinal rail profile (in particular corrugation and residual irregularities after grinding) and is typically used by the crew on a reprofiling train to decide if irregularities have been brought within acceptable limits e.g. those specified in European Standard EN 13231-3 or an equivalent.  Every RCA is validated by undertaking tests of repeatability and by demonstrating that effects of measuring speed, direction of measurement and reprofiling during measurement are minimal.  A comparison is also made in situ with a CAT to assess accuracy.


RCA (Medium Speed)

RCA mounted on a hi-rail vehicle, and used to produce grinding programme for a large railway system. Typical measuring speed of 15-50km/h.

RailMeasurement Ltd not only produces equipment to measure irregularities of microns on a rail over a wide speed range but also provides a “traceable” validation procedure for our equipment.  There are few if any other instruments whose accuracy is comparable and whose accuracy has been demonstrated so comprehensively.  Examples of the validation procedure and of pre- and post-grind corrugation measurements are given in ref [1] and in the RCA Fact Sheet.

The RCA may also be unique in providing accurate measurements of corrugation over the full wavelength range of 10-1000mm that is commonly treated by reprofiling trains and of being able to do so both during reprofiling and on freshly reprofiled rail.  The inertial principle used in the RCA does not suffer from many of the intrinsic limitations of chord-based systems that are often used on reprofiling trains [2]. Although inertial-based equipment is not without problems, we appear to have found solutions to these.

The RCA is an excellent instrument for measuring long wave irregularities, which are important for ground-borne noise and vibration. Examples that demonstrate this are shown here.

Many RCAs have been used routinely for years with little maintenance on reprofiling trains.  These continue to provide reliable measurements of irregularities to an accuracy of microns.


  1. Grassie SL, “Rail corrugation: advances in measurement, understanding and treatment”, Wear, 2005, 258/7-8, pp1224-1234
  2. Grassie SL, “Measurement of railhead profiles: a comparison of different techniques”, Wear, 1996, 191, pp245-251



RCA Data Analysis

RCA measurements taken during grinding on the last grinding pass (green) and first grinding pass (red) of a 300m grinding site demonstrating that irregularities in the 30-100mm wavelength range have been brought within the requirements of EN I3231-3:2012.