In general, railroad track is consists of rail, rail joint, railroad tie and Non- ballasted track, also called ballastless track, is the railway track. The technical concept of a railway track consisting of ballast, sleepers, and rails is very old and has stood the test of time. Such a system is simple and can be. When the new high speed line Nüremberg-Ingolstadt is opened for service in , more than km of ballastless track will be in operation in Germany.
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The different systems have undergone extensive laboratory and field tests before implementation on grade, bridges and in tunnels. Available measurement results indicate the expected favourable structural behaviour and prove the low maintenance requirements.
With increasing speed and a lay-out of lines with extreme track parameters — e.
For evaluation purposes, it is necessary to take into consideration the interaction between vehicle and track.
Passengers have always assessed riding comfort in a train by their individual impressions. Old definitions from Figure 1 could still be valid today trafk riding on the first and third generation of ICE along existing old ballasted tracks or on new high speed lines in Germany with ballastless track and trying to write in a notebook. However, there are still objective criteria to assess comfort, security and danger of distress of track components by measurement of forces and accelerations Figure 2.
The rail temperature also has to be taken into ballastess as a security criterion in respect of the danger of track buckling. The ICE 3 uses linear baklastless current brakes, which heat up the rails. An analysis by the equations in Figure 3 demonstrates that the critical temperature rise DTo for buckling of a conventional concrete sleeper track is exceeded if the extra heat from eddy current brakes sums up to 18 K.
If eight trains per hour activate a braking force of 80 kN per rail at the same track section railawy addition temperature rise would be 25 K 2i. But for a slab track S. The development of ballastless slab tracks for full service railways was initiated in Europe in the middle of the s by the planning of long tunnels where the track had to be laid directly on a rigid rock or concrete base.
In in Germany, an innovative structure was installed at Rheda station, consisting of a continuously reinforced concrete slab to which exactly aligned concrete sleepers were rallway fixed by means rzilway filling concrete Figure 4.
The reason for the ballast deterioration is the high contact pressure of the ballast due to a rigid support especially on bridges but also on grade with the perfect compacted subgrade, frost blanket layer and granular protection layer. To counteract this phenomenon more resiliency has to be introduced in the ballasted track system. Figure 5 demonstrates the effect of high resilient fastening systems on the vertical vibration velocity 3. However, this significantly increases the investment costs for a ballasted track.
Therefore, the board of DB AG decided in that, for all new high speed lines and upgraded lines to be constructed in Germany, the use of ballastless track has to be considered in the planning phase.
This enables the railway to exploit the special advantages of the slab track structure in a much better way. This change of policy by the management of DB AG has spurred the road construction companies in Germany to develop new ballastless track structures 4.
Innovative structures have to be structurally designed and tested intensively in the laboratory before they undergo trials. In general, a distinction between three basic systems can be made.
Due to the rigid structure of S. The deflection under a 20 tonnes axle load should tack similar to that of a conventional ballasted track. Long-term experiences on the latter demonstrate that the load distributing effect of the rail can be optimised by a rail deflection of about 1.
The standard fastening system of DB AG for ballastless track ensures this deflection behaviour by a resilient base plate pad with a ballasfless coefficient of The longitudinal creep resistance of the rail in one fastening abllastless must exceed 7 kN to prevent excessive gap widening of the continuously welded rail in case of a rail fracture in winter.
Ballasltess use of prefabricated sleepers guarantees exact gauge and rail inclination, which is essential for a stable wheel-set run and less wear at high speed. An advantage of systems with anchoring devices for the sleepers Figure 6 is an easy reconstruction of sleepers in the case of derailment or deterioration.
In existing old tunnels a minimum structure height can be achieved by an asphalt pavement in a thickness of only 15cm, to which sleepers are fixed. Essential for this structure is an accurately paved concrete slab. The construction of this structure can be highly mechanised, however it requires high technology and a specialised working team. All systems developed up to now demonstrated that the required accuracy cannot be achieved without any additional construction method, e.
It is well known from highway construction that jointed concrete pavements with increasing slab length and decreasing thickness tend to curl under temperature and moisture differentials, and often demonstrate pumping phenomena at joints. Hence, for high speed service, the concrete slab should be installed continuously reinforced steel content about 0.
From the results of different test sections, it is evident that the average crack spacing was reduced after three years from 3.
The risk of loosening of dowels or anchor bolts of the fastening by free cracking can be minimised by transverse notches on top of the concrete slab with a spacing of 1.
For this type of S. Hence, the thermic shrinkage of the welds caused a certain prestressing effect in longitudinal direction. An excellent long-term behaviour was obtained to date. However, the investment costs have been very high.
This type of structure nowadays became interesting due to modern production methods of the slabs and a tracm simple kind of coupling the six longitudinal bars by sleeves.
Hence a fine cracking can be activated in a spacing of 0. Decisive for thickness design is the bending stress in transverse direction, which can be reduced by prestressing. A decisive prospect of slab track is that the investment costs are not too ballawtless in comparison with the standard ballasted track. When the less engineering structures bridges and tunnels traxk, the high speed which requires efforts to increase resiliency of standard ballasted raolway and significantly reduced maintenance are taken into consideration, the slab track is more superior to ballasted track.
A reduction of investment costs deems possible by use of a frame-shaped slab track. Experiences in Japan, where this type was laid in a length of km in tunnels Hokuriku Shinkansen line demonstrated, that the costs for the frame-shaped track is eight to 14 per cent lower than that of ordinary slab track 5.
Consequently in Korea, a frame shaped S. By coupling the frames at the joints Figure 15 and notching the surface of the frames, a similar long-term behaviour can be expected as with continuously reinforced concrete slabs or the coupled slab track system in Karlsfeld. Special advantages of this type of structure are greater independency under unfavourable weather conditions and the possibility of opening to traffic soon after construction. Hence, for necessary reconstruction of a S.
Measurements by inspection cars on different concrete slab tracks demonstrate that the Q—values for track geometry remain nearly constant with increasing service time. Hence, for high speed traffic, a constant dynamic behaviour with increasing service time can be assumed, if a matured design and good quality is available. In Figure 16, the mean static rail deflection of different S.
All structures demonstrate only small differences between both measurements. The required rail deflection of 1. This wide rail seat tailway should not be used railwya high speed traack due to the danger of periodic secondary deflections between the sleepers.
In Figure 17, the variation coefficient of static rail deflection for the same S. The values give information about the scatter of resilient support. Experiences demonstrate that with a good aligned conventional ballasted track a variation coefficient of about balkastless per cent is available shortly after tamping, however with increasing service time this value increases severely due to developing track irregularities.
This value has been met with nearly all S. Dynamic deflection measurements Figure 18 raailway high speed i. Hence for a S. For the structuraldesign of S. Ballastless concrete slab tracks of different design are in revenue service for more than thirty trsck. From the existing S.
Theory of track buckling Meier – critical rail temperature raise to against neutral temperature. Vertical vibration velocity in ballast aggregates for structures with different resilient fastenings. BTD V2-structurewith concrete sleeper panel and anchors on a continuously reinforced concrete slab.
Rheda system Pfleiderer on the line Ingelstadt Nuremberg. BTE slab track Of Zublin; discrete rail seats on a continuously reinforced slab with ground surface. Test track Karlsfeld and Bogl system with coupling of continuous reinforcement. Munich University of Technology.
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Ballastless Tracks – Product Overview
This site uses Akismet to reduce spam. Learn how your comment data is processed. Website development by e-Motive Media Limited. Definition of train riding quality from Rheda structure on the Hannover-Berlin line. Bogl system on the line Ingolstadt-Nuremberg. Test track Hoesbach Frame shaped slab track development in Korea. Mean static rail deflection kN-axle. Variation coefficient of rail deflection.