Technology Readiness Levels (TRL) were first defined by NASA in 1989 as a method of classifying the maturity of a technology or product during its development and acquisition. Originally seven in number, this was increased to nine in 1991 and the concept has since been adopted by other organisations.
In 2009, the European Commission published a paper entitled ‘Preparing for our future: Developing a common strategy for key enabling technologies in the EU’. This introduced the concept of Key Enabling Technologies (KETs) as foundational technologies on which industrial prowess depends. These were listed as nanotechnology, advanced materials, biotechnology, micro- and nano-electronics (including semiconductors), and photonics.
These KETs were already using the concept of Technological Readiness Levels, due to their contacts and contracts with the US Department of Defence, as a measure of how far a technology is from being ready for use in its intended operational environment.
A group of engineers, academic, business and commercial experts adapted the concept of technology readiness specifically for the British railway system. It retained the nine levels, but put them into a railway concept as Rail Industry Readiness Levels (RIRLs) as follows: