An article on ERA contribution to development of the TSIs. The article was published in a Polish railway magazine TTS – Transport Technology Systems (Technika Transportu Szynowego), both in Polish (issue 7-8/2015), and in the special English edition, published on the occasion of international conference titled Prospects of high-speed rail in Poland. The conference was held in Warsaw on 6 May 2015. Author: Andrzej Harassek.