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What is Gauging?

What exactly is the discipline of gauging, and why is it safety critical for the railway?

It's all about clearance

Put simply, gauging is the measurement of trains and everything around it. It assesses the compatibility between the train and the network it runs on. Gauging contains a series of engineering decisions and parameters to lessen the risk of the train striking something when it is in service. It is a critical safety requirement, and any element of rolling stock, infrastructure and electrification schemes must all prove that the clearances have been considered and include safe distances.

Modern-day gauging challenges

At the inception of the railway, standardised sizes were used for trains and the infrastructure. This worked well, when infrastructure was larger than the train, there was little chance of any clashes. 

As the railway gained traction and train manufacturers became more sophisticated in production, larger trains were created to accommodate more passengers, toilets and increased freight. The challenge, however, was to ensure that these larger vehicles could still run on the railway which was widely built to the same standardised height and width. This challenge remains today.

A driving force in the digitalisation of clearance

D/Gauge's Technical Director, David Johnson started his journey as a Railway Engineer over 45 years ago with British Rail. Gauging was completed using a pole and a piece of wet string, then mapped using paper and scale drawings.

David's first challenge was to utilise the power of technology to make gauging a more universal skill. By creating a software programme, he was able to input the measurements from surveys and vehicle dimensions to create clearance figures.

As technology has developed, so have the datasets that are used in gauging. Point cloud data, LiDAR, enhanced survey measurement tools - the list goes on. Our challenge as D/Gauge is to use this data to maximise clearances for larger freight and passenger rolling stock whilst ensuring safety.

Technical Director
Probabilistic Pantograph Gauging

The future of gauging

A new methodology has unlocked more room on the network. Probabilistic gauging is a revolutionary method which assesses the factors of gauging on a probability scale. Find out more about our recent success with using probabilistic pantograph gauging.

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