Rail.co.uk Takes a Look at a Unique Train That Can Only Operate in Darkness

Published 19th March 2012

The Structure Gauging Train, the Most Important Train Running on the UK Rail Network?

DERBY - Safety is a primary concern for Network Rail, Britain’s track operator and they have a unique train based at Derby which only ever operates under cover of darkness.

It is always powered by two locomotives and has special operating instructions because of the intense light which is emitted in a thin strip in a 360 degree arc around the train.

What is the Train and Why Does it do This

Part of what Network Rail does is to ensure that the bridges, tunnels and other bits of rail infrastructure provide a safe clearance for passing trains. If, for example, something were to extrude into such a clearing area, the Structure Gauging Train would alert the local Network Rail area office, and they would rectify the issue.

The high tech laser and light technology provide a superb picture of such infrastructure. The laser beams reflect back to the train, and should the distance that the laser travels be too small, an alert is made.

The train also measures the distance between pairs of tracks ensuring that passing trains will not, in rail jargon, be affected by sub-optimal clearances. In plain English, this means collisions will be avoided!

A team of technicians man the train and sleep on it in a specially adapted coach. They monitor banks of computers and make sure recordings are safely made for scrutinising in offices.

The specially constructed light emitting coach is black on the outside and has a strip of lights inside which sends a continuous beam around the train. When this runs, it is often the only locomotive hauled train to visit the line so is of interest to those interested in railways.

For example, in October, the Structure Gauging Train covered lines in the vicinity of London’s Blackfriars and Cannon Street stations, where work on the Thameslink Programme, and redevelopment in the areas, means that the track and infrastructure will need to be re-examined. It was based at Grove Park, in South East London, for a fortnight – a rare visitor to the depot!

External Links


Have your say...

Please note: you have to be logged into the site before you can leave a comment

Liverpool street station in the UK at rush hour

Help and advice with train travel in the UK

Train travel in the UK should be a pleasure, not a headache. So if you’re taking a train on the UK railway, start your journey here. We’ve lots of hints, tips and advice to help you find your way around, travel smoothly and arrive in style by train.

Read more

eurostars passing at 375mph from the drivers seat in france


Welcome to our #railchat page. Our #railchat discussions take place over on Twitter, with our resident expert Phil Marsh. If you would like to get involved, please do join us, and use the dedicated hashtag #railchat. See our previous discussions below:

Read more

Old steam train in Shanty Town Museum

Locomotives & Engines

Our rail network would be nothing without them. From Stephenson's Rocket to British Rail Class 92 and beyond, explore the facts, information and anecdotes behind the steam, diesel and electric locomotives that built the age of the train.

Read more


Latest Tweets


Edinburgh Castle

Edinburgh to London Kings Cross by Train

Book in advance with redspottedhanky.com and save 85% advanced bookings.

From £21.00

Buy now

Millenium Dome, London

Birmingham New Street to London Euston by Train

Book in advance with redspottedhanky.com and save 92% on advance bookings.

From £6

Buy now

You may also like...



Follow us on Twitter and become part of our rail community!



redspottedhanky.com is the easy way to buy cheap train tickets online.



Control your business fuel costs with a supermarket fuel card – free to apply, no ongoing account charges and no monthly minimum spend.