Why Trains Prefer Tunneling through Mountains: Essential Safety and Efficiency Considerations

When planning railway routes that cross mountain ranges, engineers and designers often opt for tunneling through mountains rather than building tracks with steep inclines. This choice is driven by a variety of practical and essential factors, including safety, efficiency, and the technical limitations of train operations.

The Challenges of Building Over Mountains

Mountains tend to be a formidable challenge for train travel. Many mountain ranges are not easily circumvented, and the terrain can become very steep, making it difficult and costly to build suitable tracks. Moreover, a large uphill stretch followed by a long downhill journey would not be practical for trains. Additionally, the practicalities of building switchbacks and bridges to create a suitable gradient would often be more challenging and expensive than drilling a tunnel.

Technical Limitations of Train Traction

Trains have specific limitations when it comes to their ability to maintain traction. The grade, or the incline of the track, plays a crucial role in how efficiently a train can travel. Modern trains generally have a maximum grade that they can maintain without losing traction, which is measured as the percent grade (typically 2% to 3.5%). This means that spanning mountains with a steep incline would require dug tunnels or viaducts to maintain this grade.

Weather conditions can further exacerbate the issue of maintainable grade. Rain, snow, and sleet can all reduce the friction between the train's wheels and the rails, making it even more challenging to maintain a suitable grade. In situations where the track must climb steeply, snowplows would need to be deployed to keep the tracks clear, adding to the logistical complexity and cost of maintaining the route. Tunnels, on the other hand, provide a level and stable environment that is resistant to these weather conditions.

Practical Considerations for Hill Climbing

For a train to traverse a steep incline, it would need a much longer track to achieve the required climb. This design would make the route unnecessarily lengthy and cumbersome, particularly for freight trains that have to pull significant loads. Additional mechanisms like cable or cog wheels, which have been used to assist in climbing steep grades for smaller vehicles, have not been effective for long freight trains or fast passenger trains. Therefore, the use of tunnels not only saves on the length of the track but also significantly simplifies the design and maintenance of the railway.

Historical Examples and Safety Concerns

A notable example is the experience of the railway industry in Canada with the Rocky Mountains. Initially, railways were built with switchbacks and bridges, but the frequent avalanches posed significant safety risks. An avalanche that occurred while snowplows were clearing an earlier incident led to a series of train wrecks and fatalities, highlighting the inherent dangers of such a setup. As a result, tunnels were constructed to provide safer and more reliable travel for mountain trains.

Tunnels offer a number of advantages over building a track over a mountain. They are less prone to weather-related disruptions and provide a consistent and stable track for trains. The construction of tunnels also facilitates smoother and more efficient travel, reducing both travel time and the operational costs associated with maintaining a steep and winding route.

While tunnels may seem like a more costly and complex solution at first glance, their long-term benefits in terms of safety, efficiency, and maintainability make them an essential part of any railway project that involves crossing mountain ranges. Choosing the right path through a mountain can significantly impact the success and longevity of a railway route.