John Smith and Alan Sherratt have provided the pics for today's blog (3rd October 2010), both based on railway measurement trains.
The first pic is John's - two DRS class 37s are shown with the yellow-liveried overhead wires measurement coach, Mentor, (provided by Serco*) sandwiched between them. Mentor ensures that the overhead lines are in specification to supply power to electric trains. The locomotives are 37208 in front and 37069 at the rear. The pic is dated 11th October 2010; the location was Winwick.
Alan's shot is of a yellow- liveried Network Rail Test Train. A class 31, 31285 and class 97, 97303 passed through Winwick on Saturday 30th October 2010 with the a Serco* Structure Gauging Train (SGT). The working was Mossend-Derby RTC.
*Serco Rail Operations is a licensed train operator, specialising in measurement trains on behalf of Network Rail, to ensure that the UK rail infrastructure is managed as a safe transport environment. The Structure Gauging Train (SGT) uses light and laser technology to measure the distance between the track and structures to ensure that there is sufficient clearance to operate trains.