FIG Working Week 2000, 21-26 May, Prague

Trends of the Highway Tunnel Building in Slovakia

by Alojz Kopáčik

Key words: tunnel building, lay-out, control measurement, 3-D model building


1. Introduction 

A multitude of railway tunnels in the Slovak Republic on the one hand and total absence of road-tunnels on the other hand is a paradox which is a result of political and economic development in the post-war period. A comeback to the market economy in the last decenium of 20th century has been connected not only with economic and political changes but also with the decision to eliminate the retardation of traffic infrastructure development.

2. Structure of the traffic network in Slovakia

In connection with the above fact the necessity has arisen to update the national traffic routes. The Slovak Road Administration has elaborated the "Concept of the Traffic Network Development in the Slovak Republic" which re-evaluates the used network classification as well as the importance of individual routes and their classification under new conditions. The most important traffic routes are included to the network of transeuropean routes, in a volume of 852,8 km. Particular part of the conception are as follows: evaluation of the road network capacity reached, evaluation of traffic safety as well as of ecological conditions and a proposal for the gradual modernisation, including higway construction.

Design and construction of highways are in the last years connected to the more demanding parts of the routes D1 and D18. The various geological and morphological conditions of the Karpaty mountains can be not overcome without tunnels. To determination of the number of tunnels and their situation on the highway, are very important the results of the multicriterial evaluation of the region. In connection with this evaluation are designed 17 tunnels, with common longitude of 39 km, on a new highway parts.

3. Driving methods used for tunnel construction in Slovakia

In present time exist two different groups of methods for the driving of transport tunnels. The first of them is conventional tunnelling on the lines of the principles of the new Austrian tunnelling method (NATM) and the second group is tunnel driving with using tunnel boring machines (TBM). The NATM use for the hard rock excavation conventional mining explosive materials. For the soft rock excavation are used boring machines with cutting head or excavators. Tunnel driving by TBM is more impalpable to the rock and the surrounding of the tunnel is fewer affected. The both of excavation method are know in Slovakia, but the using of TBM for excavation of tunnels with large profiles (highway tunnels) are to this time not used.

4. Management of geodetic works connected to the tunnel construction

The realisation of large building constructions need the very "hard" participation of surveyors. The surveyor participate on the all of tunnel construction phases – geological investigation and preparation, design and realisation. From the viewpoint of surveyors is very demanding, if the geological investigation is realised by prospect drift. In case of the both largest highway tunnels in Slovakia (tunnel Branisko and Višňové) are driven the prospect drift. For drift excavation were used both of the named excavation method (NATM, TBM). The design of tunnel required ortophotomaps, conventional maps or
3-D models of terrain in the surrounding of the designed tunnel portals. Very important is the preparation of the documents for the land property.

The basic assumption of successful realisation of the surveying tasks during the tunnel construction, is the existence of a reliable control network. The configuration and type of network are dependent on the required accuracy of measurements, terrain requirements and lay-out methods, which are used. The largest amount of surveying tasks is connected to the tunnel construction. The surveyor groups make "daily service" for the tunnel (lay-out, deformation measurement, measurement of overbreaks, etc.).

The divergent accuracy requirements, the necessity of measurements realised in a common system of co-ordinates and their explicit connection to the tunnel construction, results in using of new integrated technology of control measurement. This technology use the modern measurement systems (lasers, electronic theodolites and totalstations) and conventional surveying methods (polygonal method, polar method, free station, etc.). Important part of this conception is the automated storage, transfer and processing of data. To this aim local computer networks on the site, connected by modems, are build. Important part of control measurement is the group of measurement they are oriented to the tunnel surface determination. The aim of this measurements is the determination of the 3-D model of the tunnel surface, which is for volume determination of the overbreaks, of the used materials, etc., used. The model can be the base of the tunnel information system, after their completion by data from another systems (signalisation, cameras, phone, ventilation, etc.) and implementation in a appropriate software. The existence of that system would be the first step to the efficient daily service and the high safety of the future tunnel.

5. Conclusion

The base of the successful realisation of tunnel is the high quality of tunnel lay-out and control measurements. The quality of geodetic works is given by the quality of the control network, the measurement technology used and the professionality of the geodetic personnel.

Assoc.Prof. Alojz Kopáčik, PhD
Department of Surveying
Faculty of Civil Engineering
Slovak University of Technology, Bratislava
Radlinského 11
SK-813 68 Bratislava

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