• Journal of the Korean Society for Railway
• /
• v.7 no.3
• /
• pp.283-289
• /
• 2004

According to continuos welded rails on a bridge, temperature changes bring about the expansion of the bridge deck adding axil forces on the track. Moreover, the ballast on the bridge deck expansion joint is moved due to the bridge deck. If bridge decks are longer, the influence is greater, loosening ballast, causing track irregularities, and deteriorating passengers' comfort. Considering structure of bridge itself and tolerance of track irregularities caused by the loosened ballast on bridges, the maximum length of a deck should be less than 80m, which is the same as the standard of the French railway. In this study, an interaction between the expansion related to the bridge length and irregularity in longitudinal level referring to measurements and maintenance works performed in the high-speed railways was analyzed. This research shows that installation of sliding plate or vertical ballast stopper is not a good option since it is difficult to install. On the other hand, installation of movable fastener or gluing is easy but its influence is insignificant. To conclude, switch tie tamping or manual tamping is more effective than others.

• Journal of the Korean Society for Railway
• /
• v.18 no.5
• /
• pp.466-470
• /
• 2015

In this study, Fenton oxidation was applied to railroad track ballasts contaminated with small amounts of oil. In order to perform the experiment on Fenton oxidation, petroleum contaminated ballast was collected from the railroad track and experiments on major factors of the remediation process were implemented in the laboratory. Then, the feasibility of insitu Fenton oxidation was investigated for the railroad track that was partially contaminated with oil. As a result, the residual TPH concentration of ballast was reduced to about 1,000 mg/kg-ballast in laboratory experiments using 0.1 mol Fe/L $H_2O_2$. Due to the drainage structure of the track bed, a considerable amount of $H_2O_2$ was released below the ballast without the sufficient reaction with the contaminated ballast; therefore, additional studies are necessary for the effective field application of Fenton oxidation.

• Proceedings of the KSR Conference
• /
• 2007.11a
• /
• pp.517-528
• /
• 2007

Domestic or international existing researches regarding rail damage factors are focused on laying, vehicle conditions, driving speed and driving habits and overlook characteristics of track structure (elasticity, maintenance etc). Also in ballast track, as there is no special lateral spring stiffness of track also called as ballast lateral resistance in concrete track, generally, existing study shows concrete track has 2 time shorter life cycle for rail replacement than ballast track due to abrasion. As a result of domestic concrete track design and operation performance review, concrete track elasticity is lower than track elasticity of ballast track resulting higher damage on rail and tracks. Generally, concrete track has advantage in track elasticity adjustment than ballast track and in case of Europe, in concrete track design, it is recommended to have same or higher performance range of vertical elastic stiffness of ballast track but domestically or internationally review on lateral spring stiffness of track is very minimal. Therefore, through analysis of service line track on site measurement and analysis on performance of maintenance, in this research, dynamic characteristic behaviors of commonly used ballast and concrete track are studied to infer elasticity of service line track and experimentally prove effects of track lateral spring stiffness that influence curved rail damage as well as correlation between track elasticity by track system and rail damage to propose importance of appropriate elastic stiffness level for concrete and ballast track.

• Proceedings of the KSR Conference
• /
• 2007.11a
• /
• pp.480-493
• /
• 2007

Many railway-advanced countries are using the various types of track to reduce the track maintenance and repair cost according to the improvement of velocity. It spends on much maintenance and repair cost for ballast track due to abrasion of ballast, track irregularity and unisotropical ballast-support stiffness. The ballast track on railway bridge is accelerating the deterioration of ballast according to interaction of railway bridge and track. As continuing the deterioration, it is caused dynamic loads. Due to these effects, it increases negative loads of track and bridge. However, when designing the railway bridge, the effect of ballast track was applicate only dead load, so elastic behavior effect of ballast track is not influenced. Therefore, this paper presumes the stiffness of ballast track on railway bridge considering dynamic behavior of railway bridge, it was evaluated that effect on dynamic behaviors of railway bridge according to ballast track stiffness.

• Proceedings of the KSR Conference
• /
• 2011.05a
• /
• pp.423-426
• /
• 2011

The excessive axial load occurred in an immovable zone of continuous welded rail(CWR) tracks threatens the security of running trains due to the track buckling in extreme hot summer. The influence factors, such as rail temperature for compressive stress, ballast resistance for track stiffness and initial imperfection of track for tracks irregularity are uncertain track parameters that are randomly varied by climate conditions, operating conditions and maintenance of track etc. So, buckling of CWR tracks has very high uncertainties. Therefore, applying the probabilistic approach method is essential in order to rationally consider the uncertainty and randomness of the various parameters. In this study, buckling sensitivity analysis was carried out with respect to the characteristics of probability distribution of lateral ballast resistance using the buckling probability evaluation system of CWR tracks developed by our research team.

• Proceedings of the KSR Conference
• /
• 2006.11b
• /
• pp.414-419
• /
• 2006

The ballast or other objects may be located on the rail road by a lump of ice, repairing operation on the track, or the strong gust due to the high speed running of the train. When a train operated in this condition, it causes serious damages to the wheel, train, and structures near the track, or the secondary ballast flying. To remove these objects safely, a ballast blower is suggested which was attached under the train. Firstly, the numerical analyses are investigated to find out the basic flow characteristics of the ballast blower. Next, the performance of the ballast blower is verified by wind tunnel experiments. Through these studies, it is expected that the ballast blower can be applied practically.

• Proceedings of the KSR Conference
• /
• 2005.11a
• /
• pp.370-375
• /
• 2005

Floating sleepers in a ballasted track increase both track deterioration and track irregularities. Consequently, a considerable maintenance work is required and maintenance cycle is shortened due to the floating sleepers. This paper quantifies the degrees of void between the floating sleepers and a ballast bed. In the future, the influence of floating sleepers on the track will be investigated by an analytical method using a dynamic model.

• Journal of the Korean Society for Railway
• /
• v.8 no.1
• /
• pp.6-14
• /
• 2005

The mechanism of ballast-flying phenomena by strong wind induced by high-speed trains has extensively been investigated by conducting wind tunnel test and field-measuring of wind velocity in the vicinity of the track. The ballast gathered from the Seoul-Busan high-speed railway track has been classified by mass and shape to find relationship between those properties and the characteristic of movement in high wind and 16-channel Kiel-probe array has been used to examine the detailed flow structure above the surface of the track. The probability of ballast-flying during the passage of the high-speed train has been assessed comparing the results from wind tunnel test and that from field-measuring. The results shows that when the G7 train runs well as the KTX train runs at 300km/h, about 25m/s wind gust is induced just above the tie and the probability far small ballast under 50g to fly is about 50％ when it is on the tie. If the G7 train runs at 350km/h, the wind gust just above the tie increases to 30m/s, therefore radical countermeasure seems to be needed.

• Journal of Korean Society of Steel Construction
• /
• v.17 no.5 s.78
• /
• pp.519-526
• /
• 2005

During summer, very high compressive force occurs on the continuous welded rail (CWR) track because of the increase of rail temperature (max. $60^{\circ}C$). This extreme temperature stress can cause the CWR track to buckle. Among many CWR parameters affecting the track buckling, the influence of the lateral and longitudinal ballast resistance was investigated on the stability of the CWR track in this study. Also, the sensitivity of the track irregularity such as the alignment defect and the gauge irregularity was investigated.

• Proceedings of the KSR Conference
• /
• 2004.06a
• /
• pp.229-234
• /
• 2004

When trains run over a snow-covered track at high speed, the snow accereted under car bodies may drop during train running. The dropped snow lumps scatter the ballast on the track damaging the car body and the environment along the track in snowy regions. In this study, various countermeasures to prevent the ballast from scattering has been investigated and compared. Furthermore, the implementation of the ballast-flying prevention methods to passing-by station has been examined through which the KTX train passes about 300km/h speed.