At the same time the Institute participated in the process of upgrading and modernization of the rail network in Poland. Experience in high speed rail, gained as a result of international cooperation and basing on the effort to increase speed on railway lines in Poland (so far 200 km/h), is included in the monograph “Koleje Dużych Prędkości w Polsce” (High Speed Rail in Poland) published in 2015 for the benefit of the Polish reader. This monograph aims at reaching an international audience of experts so as to present Polish determinants of HSR implementation. In order to elaborate this monograph, apart from specialists from the Railway Research Institute, experts from other research and academic centres were invited. Not only presenting a wide range of problems connected with future construction of High Speed Lines in Polish conditions, but also a number of operational ones. The authors have created a reference work of universal character, solving problems in order to build and operate high speed rail systems in countries on a similar level of development as Poland. Features: Presenting these problems on the international arena will facilitate future cooperation and application of world experience to create HSR in Poland and integrate the Polish HSR network into the international one.