Geodetic survey and track recording vehicle data combined for the accurate setting out of rails on slab track

Track geometry quality is a critical factor for the safety of modern railway systems. It is achieved through a number of track surveying parameters that, in essence, characterize the quality of the absolute and relative rail locations. Nowadays, two methods are widely used for acquiring accurate track surveying data; standalone geodetic surveys and kinematic track measuring systems. Despite the rapid growth in the use of track recording trolleys in the past few years, it has become clear that, depending on the special features of a construction project, the combineduse of both systems can increase the reliability of track geometry quality with profound effects on construction costs and operational safety. This paper presents the basic concept of track geometry surveying, describes the surveying techniques and compares the rail laying quality measures obtained from the implementation of the two methods during the construction of the modern tramway of Athens.