Gauging, or demonstrating compatibility between train and infrastructure, covers techniques that ensure sufficient space exists around a moving train to provide safe operation. These techniques have evolved into a complex set of processes to manage the risk between moving trains colliding with infrastructure and other moving vehicles.
UK’s railway started life as many isolated routes with no real standardisation; the infrastructure was built and operated by small private companies with purpose built rolling stock and infrastructure to suit the individual route. Gauging was managed by ensuring a suitable gap remained between the infrastructure and static rolling stock—this gap was manually measured, usually with a physical gauge on site. The gap would allow for movement of the vehicles suspension when travelling, plus extra for any known and unknown tolerances.
Today, routes have been amalgamated and much of the network has been standardised, but the legacy of linking the non-standardised railways can still be recognised, especially when dealing with gauge capability.
Gauging covers a series of techniques that ensure sufficient space exists around a moving train to provide safe operation. This space is referred to as clearance. These can involve simple or complicated processes, the simplest uses gauges, but these are not appropriate to all circumstances. GERT8073 defines the standard vehicle gauges used in GB and how to apply them. If vehicles can be built to standard gauges, then this is the simplest and cheapest method of gauging, as most of the 'clearance' work has already been done.
Here we provide information prepared by the Vehicle / Structure Systems Interface Committee and present the processes available, explain their limitations and, perhaps most importantly, the reasons for such limitations.
The stages for gauge compliance are summarised in the flowchart ‘Appendix A-Route to Gauging Compatibility Demonstration'.
