Here you will find a summary of the terms used within this website and the project as a whole.

cant

The vertical difference in height of the two rails of a track system, used to give stability to vehicles running on curves. This can also be referred to as superelevation.

cascading

Cascading is the process by which resources are handed from one sector of the rail network to another as they are replaced by newer stock. The movement is always from stretches of line requiring higher quality (such as higher safety-tolerances) to areas of lower requirements. This process often includes rails and rolling stock, but can also refer to the movement of other resources.

fishplates

This is the name given to the bolted metal plates used to connect separate lengths of rail.

flange climb

This refers to the mechanism of the wheel flange rising up over the profile of the rail head and resulting in the wheelset leaving the permanent way.

flange

This is the portion of rail vehicle wheels that steers the wheelset and prevents rolling stock from leaving the permanent way.

formation

Refers to earthworks such as cuttings and embankments on UK railways.

heritage railway

Heritage railways are those lines not part of UK mainline railway operations (primarily under the control of Network Rail) and run as a tourist attraction, often by volunteers. These are typically managed to emulate railway operations of the past.

photoelasticity

This modelling technique relies on the principle that some transparent materials such as Perspex, celluloid and some epoxy resins display patterns along lines of equivalent stress when exposed to cross-polarised light, allowing the identification of stress distributions. By constructing miniature two-dimensional models in these materials then exposing them to working stresses it is possible to highlight areas of likely weakness and failure. The phenomena were first described by Scottish physicist David Brewster in the early 1800s.

residual stress

This is an inherent property of manufactured steel elements and refers to the stress in a component not being exposed to any external loading.

route availability

In the UK Route Availability refers to the maximum at-axle vehicle tonnage permitted along a stretch of railway line. This is usually limited by the capacity of bridges and earthworks, and is identified by using a number from RA1-RA10 (low to high tonnage with a maximum of 25.4 tonnes), with the associated axle tonnages being defined by the Rail Group Standards.

serviceability limit states

These design limits are determined by the point at which a structural element is no longer fit for purpose. In the case of rail, this usually means that the rail profile is likely to result in flange climb or excessive wheel wear.

sleepers

This is the name given to the transverse supports that distribute the load from rolling stock and transfer it into the ballast and substrate, whilst maintaining the distance between the running rails.

sorbitic and pearlitic steel

Sorbite and pearlite are crystal structures of steel. The formation of these intermediate structures can be induced in the manufacturing process and heavily contribute to the surface resistance of steel rails. The Sorbitic treatment of rails through quenching rolled rails in steam to achieve a critical cooling speed was developed by Christer Peter Sandberg in the early decades of the twentieth century (Sandberg & Sandberg, 1938).

standard gauge

Standard gauge is the name given to the most commonly used rail layout in the UK and refers to the distance between steel running rails, in this being case 1435mm (4ft 8½in).

substrate

In the case of railway engineering this usually refers to the support immediately underneath the rail sleepers, and is usually in the form of limestone or granite ballast of a specified dimension.

track modulus

The resilience of the track system to loading. If a high loading is required to generate a given vertical deformation in the height of the running surface then the track modulus will be high.

track system

The track system refers to the structural arrangement of rail, fixings, sleepers, ballast and associated mechanical components that permit the movement of rolling stock on railways.

ultimate limit states

In design this refers to the point when any element has exceeded its structural strength. In the case of steel rails, this may refer to a brittle rail break, fraying at the rail joint or buckling failure under compressive load.

If you are unfamiliar with a term used in this website and it is not defined above, please feel free to contact the author by going to the contacts page here.