The railway track manufacturing is fast developing these years as well as the railway track construction technology. The process of building railway tracks has been evolved in the late years. The gradual development is changing with the upgrade of railroad tracks for sale. The old way of track construction mainly counting on numbers of workers using simple tools. Now, things are quite different since the innovation and application of modern railway construction machine. With different types of modern machines, the job gets done much easier and saves labour and time. Especially when it comes to building a high-speed rail with lengthening rails (one section 500meters long or more), the efficient work of construction is essential.
Process of building railway tracks
- Logistics preparation
A logistic station is chosen as near as possible to the railway construction site. All the track material needed for railway construction is stored there. Concrete sleepers have been strategically placed. These sleepers are later loaded onto the empty tie cars and the loaded cars are moved to the track construction machine for installation. On another occasion, rails are installed on the sleepers advanced here and later being laid on roadbed by machine.
- Bottom ballasting
Theoretically, the rails should be laid on the pre-paved and tamped trackbed, but due to a large amount of ballast required per kilometer of the railway (up to 2,000 m3 per kilometer), the railway itself must be used for transportation to reduce freight and shorten the construction period. Therefore, other means of transportation are generally used first, and only a small number of ballast (or even just two layers of ballast under the rails) are laid. Trains are used to fill up the ballast as soon as possible after the tracks are laid.
The ballasting work includes many operations such as transportation, unloading, spreading, lifting track, lining the track, tamping, and ballast bed shaping. Among them, the transportation and unloading of ballast are mostly carried out by special automatic ballast unloading vehicles. For other operations, most countries use ballast machines with comprehensive work performance.
- Sleepers and tracks Laying
Normally, sleepers are laid first and railway tracks are laid next. However, they can be laid together at one time if the rails and sleepers are combined previously.
- Sleepers and tracks are laid separately
One typical track construction machine is composed of a caterpillar, the main control operation, a self-propelled gantry. It can lay new sleepers, thread new rail, clip the rail to the ties.
The new rail which was previously positioned along sides of the way that threaded to the rail guides located at the front of the unit. The main control operation monitors the conveyor systems and the sidewalk mechanism. The self-propelled gantry keeps ties supplied to conveyor systems. The gantry moves to the tie receiving conveyor deposits ties and returns to the tie supply car for another load. After being deposited by the gantry, the ties moves by a conveyor system through the ties drop area. The ties are discharged from the tie placement mechanism and are precisely spaced on the roadbed. After the rail passes through the rail guides it is guided into a gauging station. The final placing of the rail to the ties is controlled by an operator who guides the rail onto tie seat. The clipping is carried out by nipper clipper mechanism near the rear of the machine.
- Sleepers and rails are laid at one time
Another way of railway track installation is laying rails pre-assembled with sleepers. Sections of rails and sleepers are placing together in advance at the logistic area. Then it is loaded on a special flat car with wheels which is transported to the track laying machine. This machine has simple structure with a jib crane which lifts the assembled rails down to the ballast. After one section is finished, another lift begins to connect the two parts of rails.
Things need to notice:
In the process of laying railway tracks, the front of new rail just laid should be padded with some ballast properly to prevent being lowered by the front wheels of the track laying machine which may cause difficulties in the following process of a rail connection. Also, pay attention to the situation of roadbed, especially in areas with soft roadbed or poor geological conditions, reinforcement work should be done in advance. Once there are settlements or cracks, measures should be taken immediately to quickly retreat the track-laying train to ensure safety.
- Top ballasting
As we mentioned before, only the bottom ballast has been laid. The top ballast is needed to form a solid foundation. The procedure mainly comprises the following steps: ballast unloading – ballast spreading – track lifting – track lining – tamping. After the ballast is fully loaded and pressed down by trains for several times, the final repair will be done.