MONITORING OF THE TRACK GEOMETRY QUALITY AROUND THE PORTALS OF NEW TUNNEL CONSTRUCTION TURECKY VRCH - PRELIMINARY RESULTS MONITORING OF THE TRACK GEOMETRY QUALITY AROUND THE PORTALS OF NEW TUNNEL CONSTRUCTION TURECKY VRCH - PRELIMINARY RESULTS

concrete or asphalt substructure (slab). The structure of slab track proved to be practical and preferred structural system of railway superstructure in many railway reports, which has led to its spread practically all over the world. The essential reason for building the structure of slab track is the fact that its construction gives high stability of the track which is associated with a smooth movement of vehicles and at the same time with driving comfort for the passenger and the operator with significantly lower maintenance requirements and thus the possessions and finance. This high driving comfort can be obtained, in the case of the application of standard structure of railway superstructure, only with the connection with very high operating costs. In general, the structure of slab track currently applies mainly to high-speed lines and lines that have high line tonnage where the cost of maintaining the track with the standard structure At the beginning, the contribution deals with the characteristics of conventional structure (track skeleton placed in the ballast) and unconventional structure (slab track) of railway superstructure. The trial section is characterized in the next part where measurements of relative track geometry are made at regular intervals (spring and autumn) using continuous measuring device (manual measuring trolley KRAB TM - Light). There is made the analysis of measurements made between 2012 - 2013 at the end of the contribution; with a view to asse-ssing the quality of track geometry during particular sections monitored with in-built conventional and unconventional structure of railway superstructure. It also includes transition areas between these structures and an analysis of possible causes of variations in track geometry of modernized railway sections monitored.


Introduction
Considering the railway operation, a standard structure of railway superstructure has been proven for many decades which is historically also known to be capable of ensuring a relatively long period of operational capacity of the railway line. From a structural point of view, such a railway track with the standard structure of railway superstructure is referred to as a railway track whose track skeleton is stored in railway ballast. In the case of high line tonnage and axle load, increasing track speeds which are associated with the high quality requirements for track geometry, it appears that such a structure has its operational (in terms of guaranteeing the long-term safety and reliability of the track) and economical (in terms of the cost of track maintenance) limits. Standard structure of railway superstructure is characterized by "floating" placement of track skeleton, which causes the growth of dynamic horizontal and vertical forces during each passage of a rail vehicle or a train. They may and usually cause gradual degradation of track geometry which subsequently leads to restless driving of rail vehicles. The elimination of irregularities in track geometry -the quality of the track -forces the operator in a period of time to remove irregularities of track diagnosed by time and costly maintenance works. This phenomenon grows with increasing track speed and thus increases the cost of maintaining and share of track possessions, which reduce the attractiveness of the track for a passenger. It is sufficient, however, if only the weakest structural element of the standard railway superstructure is replaced in railway track, and the track ballast is another, more appropriate structural element which shows no plastic behaviour. Such replacement is a structure in which the track skeleton is concreted (monolithic structure) or placed on a concrete or asphalt substructure (layered structure), thus the design of railway track which is referred to as unconventional superstructure. Currently, thus conceived railway track is referred to as a slab track in which the required flexibility of the railway superstructure system for the wheel/rail is ensured using the flexible structural elements, disposed between the rail and the sleeper and/or under the sleeper.
The term slab track, as defined in [1], refers to such a structure of railway superstructure in which a spread function of railway ballast is replaced by reinforced materials, and which is placed on a concrete or asphalt substructure (slab). The structure of slab track proved to be practical and preferred structural system of railway superstructure in many railway reports, which has led to its spread practically all over the world. The essential reason for building the structure of slab track is the fact that its construction gives high stability of the track which is associated with a smooth movement of vehicles and at the same time with driving comfort for the passenger and the operator with significantly lower maintenance requirements and thus the possessions and finance. This high driving comfort can be obtained, in the case of the application of standard structure of railway superstructure, only with the connection with very high operating costs.
In general, the structure of slab track currently applies mainly to high-speed lines and lines that have high line tonnage where the cost of maintaining the track with the standard structure and implemented according to the technical specifications for interoperability for conventional lines. It is convenient to the latest trends in tunnel and railway construction and should become a model for all future tunnels which will be built in Slovakia in terms of the modernization of railway lines. Doubletrack railway tunnel Turecky vrch is designed to structure gauge UIC C with the track-centre distance 4 200 mm. The total length of the tunnel is 1 775 m, while the tunnel tube of the section excavated has the length of 1 738.5 m and thereon pierced sections of the south portal length of 25 m and northern portal length of 10 m. There is a single cross-section of double-track tunnel with a radius of tunnel tube of 6.1 m throughout the entire length of the tunnel, including portal sections; there are only two chambers in the middle of the tunnel for tensioning mechanism spring for the overhead lines with advanced cross-section. Doubletrack in the tunnel is designed for the speed of 200 km.h -1 with the reverse curves of the radii 2 000 m.
The structure of the slab track was designed, as already mentioned, due to the reduction in the slope area and also due to the durability and fixation of the track geometry and its minimum maintenance in the operation. The structure of the ST of the RHEDA 2000 ® system applied passes through the different types of subgrade. It starts before the south portal and passes through entire tunnel. Then, the structure of the slab track continues on the bridges and earthworks behind the north portal. It is clear from the previous text that the structure of the slab track of RHEDA 2000 ® system applied is not structurally the same on the modernized track section due to differences in the stiffness of the subgrade (tunnel bottom, bridge and railway substructure of earthwork), but is modified, which is reflected in the thickness of the concrete structure and also its reinforcements. The structure of the slab track is divided into 3 basic structural types in the track section in question as follows [2] and [3] and, in particular, to the tunnel clearance gauge, as there are required properties of the subgrade which do not show settlement of foundation. Furthermore, the use of the slab track structure has a positive impact on the size of the investment costs of tunnel realization, due to the smaller tunnel clearance gauge, in the case of new tunnels, or excluding economically demanding reconstruction of tunnel, in the case of its electrification on the existing tracks. The structures of slab track and bridges offer the application of subgrade without the settlement of foundation, and therefore, the application of this structure is also possible in these track sections.
In connection with the modernization of the trans-European corridor V. Venezia -Trieste / Koper -Ljubljana -Budapest -Chop -Lvov; with a branch Va, passing through the territory of the Slovak Republic in the section of Bratislava -Zilina -Kosice -Cierna nad Tisou -Chop was, under the construction of Railways of the Slovak Republic (ZSR). Modernization of railway track Nove Mesto nad Vahom -Puchov, in track section Nove Mesto nad Vahom -Trencianske Bohuslavice, designed by the construction contractor (REMING Consult, a. s.) and the purchaser (DG Slovak Railways -DG SR) and approved the structure of slab track type RHEDA 2000 ® . After analyzing alternative solutions of routings around Turecky vrch in the current track of railway line and a new route -tunnel variant -the purchaser decided for the tunnel variant. It is considered that the change of routing of a railway line through the tunnel will increase the current track speed while minimizing adverse impacts on the protected landscape area where the track is led through. Another advantage of the tunnel variant in the decision making process of routing was that the construction of a tunnel did not restrict railway traffic because the tunnel was pierced outside the axes of original track.
In the view of the fact that in the case of necessary maintenance, or future repair and reconstruction works, the implementation of these works in the tunnel is complex. Moreover, due to the reduction of the amount of rock mined from the tunnel profile, which did not have further use, the structure of slab track, which has a lower structural thickness as in the case of using a standard structure of railway superstructure, was the appropriate solution. The critical point of the slab track structure is its completion and transition to the standard structure of railway superstructure -Figs. 7 and 8. In terms of dynamic effects, this is a place with the change of stiffness and, hence, this place was given special attention. The concrete bed of the length of 20 m was designed where it is expected that the relevance of the implementation of the slab track is shown in this track section modernized and, at the same time, the above mentioned advantages of the operation of the structural system of railway superstructure are confirmed in terms of the Railways of the Slovak Republic as well.

Preliminary results of the monitoring of track geometry quality -a comprehensive diagnostics of the relative track geometry
In this paper, only the diagnostics results of relative track geometry are presented also in relation to the previously realized diagnostics of structural layers built, which are part of the slab track subgrade, or subgrade structure and which was implemented in the inspection of the quality of the track section built between  detection of maintenance limits, the quality of the straight section or section in transition curve and curve is specifically evaluated in accordance with [7]. Local errors of the parameters measured are calculated separately for sections with the standard structure of railway superstructure (SSRS), for transition areas and sections with the slab track structure.
The overall superevaluation of test sections (so called "section evaluation") is, in accordance with [1], given by the quality number of the section evaluated (QN), and quality mark (QM) of SP parameters (SL), RK, PK and VR (VL). As already mentioned, first activities were made before putting line tracks No. 1 and No. 2 into operation in 2012 within diagnostics of above characterized track section. The effect of subsequent repair activities (rail grinding, track lining and levelling), implemented under maintenance operations of railway infrastructure manager between the measurements in 2012 and 2013, was not taken into account in the evaluation of relative track geometry, as the working site performing monitoring was not provided with these results of activities.
The development of track geometry (hereinafter referred to as RK) of the monitored sections of southern and northern portal of the tunnel Turecky vrch is shown in Table 1 to  The ranges of differences of gauge deviation values ΔRK and deviations of track elevation PK are shown in Table 5.

Analysis of the possible causes of deviations in track geometric parameters of the track
Static load tests (SLTs) were implemented at the level of subgrade and on the surface of individual structural layers of the track in the sections of the railway track built between 2011 and 2012. Continuous testing of the structural parts in question using SLT has achieved that there have been immediately obtained an overview of the quality of the incorporation of individual rock materials (determining the degree of compaction) and deformation resistance reached in the level of structural layer tested expressed by static module of deformation E s,i .
Static load tests were carried out in (Fig. 9)  On the basis of comprehensive diagnostics of the relative track geometry it is possible to identify some trends in the growth of deviations in places where the desired values of compaction degrees or deformation resistance were not reached, whose origin may resulted just in the deficiencies in the structure of railway substructure [7]. The results of quality section evaluation of track according to quality marks are indicative and additional on the railway tracks of the Slovak Republic and are not binding for the evaluation of TG state. Measures, which are set for individual intervals of quality marks, can provide only recommendations: a) where 0 < QM ≤ 2, state of track geometry is satisfactory in section evaluated, b) where 2 < QM ≤ 3, it is recommended to design the repair of track geometry in the section evaluated into maintenance work plan, c) where 3 < QM < 4, it is recommended to perform the repair of track geometry in the section evaluated to the nearest control, d) where 4 ≤ QM ≤ 6, it is recommended to perform immediate measures in the section evaluated to ensure the safety of operation [1].

Comparison of gauge and elevation measurements before putting test section into operation, the first operational measurement and the second operational measurement
The difference of values of gauge deviations found in PO1 and MSO is in the range from 1 Table 6 that in some places in which the required value of the static module of changes E s,i or consolidation quality E def2 / E def1 has not been reached, parameters of track geometry show a negative trend, therefore, it is possible to predict that the worsening trend of parameter deviations of track geometry may have originated in the deficiencies in the deformation resistance or consolidation of the structural layers of slab track, or subgrade structure when operating.
Directional and vertical routing of a railway line does not have a demonstrable impact on the negative tendencies in the deviations of the parameters of track geometry. The parameter values have also been monitored in other places that could be problematic (culverts, slab joints of the slab track structure, transition area wedges), but no clear errors in the track geometry apply to these places.
Complex diagnostics of relative track geometry shows similar deviations as in the sections with the standard structure of railway superstructure and the sections with the slab track structure as well. Significant deviations are not yet recorded in the transition areas between the conventional and unconventional structure of railway superstructure.

Conclusions
An essential precondition for the competitiveness of rail transport is the reliable operation of the railway lines, considering the technological understanding, it means a safer and more stable movement of vehicles along the track -rail. The development and validation of a number of technical solutions of slab track in the longer term can ensure the quality of the track geometry parameters, reduce maintenance costs, extend the service life of structure and increase the competitiveness and attractiveness of railway lines. The issue of modernization of the railway infrastructure, which is still very current, is an ideal opportunity to further application of progressive systems and elements of the structure of railway lines, among which the structure of slab track undoubtedly belongs to.
The results of continuous diagnostics of relative track geometry do not show local errors of parameters during operation in any of the diagnosed sections. The total numbers of quality The places of origin of negative trends in the values of the track geometry on the basis of the deficiencies in the structure of railway subgrade are shown in Table 6. The places where the desired value of the deformation module was not achieved, or quality of consolidation are marked in red, the parameter values of track geometry which show a negative trend, and it is appropriate to monitor them closely are marked in blue).
Differences of values ΔRK and PK measured within MSO, PO1 and PO2 Table 5 Track deteriorated in the other four partial sections (max. from 1.24 to 1.50).
On the basis of experimental measurements made so far, it is possible to expect that further development of the monitoring of RK in experimental section of the modernized track in the (QN) in diagnosed sections have even slightly improved within the second operating measurement in the four of the eight subsections as opposed to the first operating measurement (maximum improvement is from 1.59 to 1.18) and they slightly Analysis of the causes of deviations in RK parameters Table 6 Stationing