SUPERSTRUCTURE MODERNIZATION OF THE HEAVY GANTRY CRANE TRACK IN TPP REK BITOLA

Abstract

This paper presents a comprehensive engineering solution for the rehabilitation and structural modernization of a severely degraded gantry crane track at the Thermal Power Plant (TPP) REK Bitola. The investigated crane, a 383.4-tonne portal structure manufactured by Metalna in 1977, was withdrawn from operation due to significant geometric deterioration of the crane track. Long-term geodetic monitoring and recent levelling surveys identified vertical rail deflections exceeding 30–40 mm, far beyond the permissible operational tolerance of ±3 to ±5 mm. The investigation showed that the primary causes of deterioration were the structural decay of the existing wooden sleepers, ballast contamination and inadequate drainage, while the underlying platform exhibited excellent bearing capacity (CBR = 100%) and did not require rehabilitation. The proposed rehabilitation concept focuses on the complete modernization of the track superstructure, utilizing the high-bearing capacity of the existing subgrade. The existing wooden sleepers are replaced with pre-stressed reinforced concrete sleepers (type RAJS-K-B70) tailored for the 1500 mm track gauge, supporting S49 rails via an elastic Vossloh SKL 14 fastening system. Additionally, the configuration features an elevated ballast prism and a newly integrated longitudinal drainage system equipped with perforated Ø100 mm pipes. The structural design was developed in accordance with established railway track design principles to ensure adequate load transfer, improved track stability, efficient drainage and long-term preservation of the track geometry. The proposed solution provides a practical engineering approach for restoring the operational reliability of industrial gantry crane tracks and may serve as a reference for similar rehabilitation projects under comparable operating and environmental conditions.