PKP Polish Railway Lines S.A.   PKP Polish Railway Lines JSC Company (PKP Polskie Linie Kolejowe SA - PLK) is a State-owned company, run along commercial lines, responsible for managing the railway network in Poland. The main functions of the Company are:   construction and maintenance of rail infrastructure,   handling the rail traffic on railways lines,   maintenance of rail infrastructure in the condition ensuring safe handling of rail traffic,   allocation of train paths on railway lines and providing relevant services,   management of real estates belonging to the railroad infrastructure.   The railway network infrastructure functions managed by PKP Polish Railway Lines JSC are: permanent way (tracks, turn-outs), level crossing, civil engineering structures (bridges, viaducts, subways, culverts, line tunnels, footbridges, retaining walls), platforms, signaling towers and all other structures necessary for railway operation. PLK also manages train operation and signaling systems together with low-voltage power supply.   The investments carried out by PKP Polish Railways Lines JSC mainly concern demands faced in connection with the European integration processes. One key challenge is to provide accessibility to all areas within the European Community, i.e. within all 25 Member States of the European Union.    With relations to Poland’s merge into the European Union (EU) and by its assistance aiming for a modernization of the railway lines located on the TINA network. In this work PKP PLK S.A is responsible for:   preparation of projects, carrying out of tenders, signing of contracts with contractors, supervision of work of engineers (with relation to investment projects) and consultants (with relation to technical assistant projects), making of payments to contractors, submitting of payment claims to the Ministry of Infrastructure, recovering of undue payments from Contractors,  keeping of the books of the projects co-financed by the EU.    Participation in Project „Sustainable Bridges” is one of the activities, which are expected to bring Polish railway system to highest European quality level.