EUROPA XXI Vol. 28, 2015, pp. 33-52 http://dx.doi.org/10.7163/Eu21.2015.28.2 Institute of Geography and Spatial Organization Polish Academy of Sciences www.igipz.pan.pl NEW INVESTMENT PROJECTS IN THE ROAD CORRIDORS AND THE IMPROVEMENT OF THE POTENTIAL ACCESSIBILITY IN POLAND Tomasz Komornicki, Marcin Stępniak Institute of Geography and Spatial Organization Polish Academy of Sciences Twarda St. 51/55, 00-818 Warsaw, Poland t.komorn@twarda.pan.pl, stepniak@twarda.pan.pl Abstract. The purpose of the study, whose results are reported in the present paper, was to assess the changes in the spatial accessibility, resulting from the realisation of large road investment projects in Poland in the period 2004–2013. Attention was primarily focused on changes in overall accessibility and on investment projects, constituting three chosen case studies. The method, selected for the measurement of the level of spatial accessibility and of its changes, was based on the indicator of potential accessibility. Each analysis was carried out in parallel in three dimensions: European, national, and regional. It was stated that the improvement in the international and national accessibility, which took place in Poland due to the road projects, was highly uneven in space. It was determined by the location of the routes constructed and the distribution of the demographic potential in space. The resulting distribution of accessibility became more polarised, this being inevitable in the situation of undertaking numerous projects within a short time. The projects realised served more the international and inter-metropolitan connections, while their influence on the improvement of the situation within the provinces was smaller. The study confirmed the earlier apprehensions that the motorways might produce the “tunnel effect” (understood as limitation of the service to uniquely the long-distance connections). This sort of threat is decidedly smaller in the case of the expressways. It was also demonstrated that the correct location of the nodes might have a perceptible impact on the spatial reach of the positive effects from the projects. Keywords: potential accessibility, Poland, road projects. Introduction The purpose of the study, whose results are reported in the present article, was to assess the changes in the spatial accessibility, being the effect of the realisation of large road projects in Poland in the years 2004–2013. The study was performed in the framework of the research project Multicriteria assessment of the influence of selected road corridors on the natural environment and on the socio- economic development of the adjacent areas (no. N N306 564940) financed with the resources from the National Science Center. Attention was mainly concentrated on the changes in accessibility in general terms and on the investment projects, constituting three selected case studies: