Why Choosing Wood and Crushed Rocks for Train Tracks is Still in Fashion
Despite advancements in technology, the traditional use of wood and crushed rocks for train tracks remains prevalent. This article explores the reasons behind this choice, with a focus on the benefits of using these materials over concrete sleepers in specific contexts.
The Structured Role of Wood and Crushed Rocks in Rail Infrastructure
Traditionally, train tracks have been constructed using a combination of wood and crushed rocks. This method was adopted before the widespread use of concrete prefabricated sleepers. Even in modern times, wood is still commonly used on branch lines and sidings, particularly in areas where very little maintenance is expected. This is due to its superior vibration absorption capabilities, especially in larger switch layouts.
Crushed rocks are used as ballast under the track, playing a critical role in distributing the pressure exerted by the train's weight onto a larger surface area. This helps prevent the rails from sinking into the ground or crushing the underlying rocks. The use of crushed rocks also provides drainage, which is crucial for maintaining the integrity of the tracks.
The Role of Sleepers and Tie Plates in Train Tracks
The rails are attached to tie plates, which are further nailed or "spiked" into the sleepers (also known as ties). Sleepers serve the essential function of transferring the weight of the train evenly onto the ballast, thereby preventing damage to the rail and the underlying structure. Wooden sleepers, in particular, are favored for their elasticity, making them ideal for vibration absorption both vertically and laterally.
Cost, Elasticity, and Workability of Wooden Sleepers
Wooden sleepers remain a cost-effective choice, especially given the vast number required. Their elasticity offers additional benefits like reducing the noise produced by trains. However, it's worth noting that at high speeds, this same elasticity can lead to serious safety issues. Wooden sleepers are also lightweight and easy to handle and transport, making them a preferred choice for initial installation costs. In the 19th and early 20th centuries, railroads primarily focused on minimizing these initial installation costs, assuming that once the railway was built with sufficient revenue, rate hikes could fund maintenance, including the replacement of sleepers.
Climate Considerations and Geographical Preferences
In very dry climates, where the rate of wood decay is minimal, wooden sleepers are still preferred. This aligns with the cost-benefit analysis, where the long-term benefits of wood's durability in dry conditions outweigh any potential drawbacks. Conversely, in regions with frequent rainfall, the use of concrete sleepers is more popular. These concrete sleepers offer longer lifespans, greater stability, and the ability to accommodate higher speeds and heavier loads, despite the higher initial costs.
Evolution in Railtrack Maintenance and Installation
Modern rail installation and maintenance have shifted towards automated vehicles, making manual labor costs irrelevant. As a result, the choice between wood and concrete sleepers is increasingly guided by economics rather than labor considerations. Tracks with heavy traffic are gradually being converted to concrete sleepers, and the replacement of old branch lines with concrete sleepers has been ongoing since the 1990s. This trend towards concrete reflects a broader shift in focus from initial installation to long-term maintenance and operational efficiency.
In conclusion, while the use of wood and crushed rocks for train tracks is waning, these materials remain an integral part of railway infrastructure, particularly in areas with specific climate and maintenance requirements. As technology continues to evolve, the choice between wood and concrete sleepers will be increasingly determined by a rigorous cost-benefit analysis.