Always known as Lab 5 the 2-car unit was based on a Park Royal Class 103 and numbered RDB 975089 & 975090

Lab 5 carried equipment which was used to develop the track recording technology for British Rail. It carried a series of sensors, processing instrumentation, tape and chart recorders. This allowed the monitoring of such information as rail heights (Profile), Gauge, Alignment, Cant, Curvature, Gradient, and ‘Track Corrugations’ every 9 inches, at speed up to 125mph.

For some time it also utilised quite a rare Analog Computer onboard, which was later replaced by digital computers which gave summary printouts or plots. The resultant data was analysed and also passed to the relevant civil engineers.

Lab 5 was trialled and calibrated at the Old Dalby Test Site, and made many trips along a series of routes in the UK, including regular Derby-York-Middlesborough-London-York-Derby runs, and some to the South West, and even toured Scotland and certain London Underground routes.

Once proven, each revision of the technology was then deployed on the Civil Engineer’s High Speed Track Recording Coach.

In October 1976 Lab 5 was shipped to Zeebrugge to carry out a track survey in Holland for an ORE project

Between December 1984 and January 1988, before the LUL Track Recording Vehicle entered service, Lab 5 was used to collect track data for those sections of LUL track over which the vehicle was in gauge. The unit was self-propelled and driven by a BR driver with a LUL pilot.

Look on Departmentals.com for a few more pictures http://www.departmentals.com/photo/975089975090-5

Lab 5 at Derby in the late 1980s

Paul Hadfield

47431 with Lab 5 in tow at Doncaster in the late 1980s

Jeff Pugh

On the murky morning of 6th February 1990, 47973 hauls Lab 5 north out of Derby,