Track-recording techniques used on British Rail

Accurate and consistent data on railway-track quality is required from which track-maintenance action can be scheduled. In recent years two recording vehicles have been designed by British Rail: a high-speed track-recording coach (HSTRC) to provide maintenance data for the Civil Engineering Department, and a self-propelled diesel multiple unit used by the Research and Development Division for investigative work. For HSTRC a measuring system was needed which would be reliable under intensive running conditions, and which could be fitted to a standard coach with the minimum of mechanical modification. Conventional multiwheel or multiprobe systems were rejected because of the considerable mechanical complexity of the undergear, in favour of a single-point system using inertial techniques and measuring in the vertical plane through the running wheels and in the horizontal plane through noncontacting optical-scanning equipment. The inertial measuring system uses transducers, including accelerometers, rate gyroscopes and displacement transducers which provide inputs to special-purpose electronic processing networks which provide the required profiles. Onboard computer systems analyse the data to form track-quality estimates which are listed and recorded on magnetic tape for transfer to a central mainframe data bank. Operation of the track-recording coach is controlled by an automatic route-definition procedure using data stored on a central track-route data bank.