Curves Necessity, Functions and Type - Geometric Design of Railway and Traffic Control | Summary and Q&A

TL;DR

Railway curves are essential for safe and convenient train travel and serve the functions of providing gradual changes in direction and gradient, easy turning of trains, and passenger comfort.

Key Insights

• 👷 Curves are integral to railway construction and serve important functions in facilitating changes in alignment and gradient.
• 🏝️ The necessity of curves arises from the need to bypass obstacles, provide easier gradients, avoid excessive cutting or filling, and minimize land acquisition costs.
• 🚄 Grade compensation is necessary on curves to overcome increased tractive resistance and maintain train speed.
• 👷 Horizontal curves in railway construction include simple curves, compound curves, reverse curves, deviation curves, and transition curves.

Transcript

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Questions & Answers

Q: What is a curve in railway construction?

A curve in railway construction is a geometrical arch that is provided at the change in alignment or gradient of a track.

Q: Why are curves necessary in railways?

Curves are necessary in railways to bypass natural or artificial obstacles, provide easier gradients, avoid excessive cutting or filling, and avoid expensive land acquisition.

Q: What are the functions of providing curves in railways?

The functions of providing curves in railways are to provide gradual changes in direction and gradient, allow for easy turning of trains, and ensure passenger comfort.

Q: How does grade compensation work on curves?

Grade compensation on curves involves reducing the gradient to overcome increased tractive resistance and allow trains to maintain the same speed. This reduction in the gradient is expressed as a percentage per degree of curve.

Q: What are the different types of horizontal curves in railway construction?

The different types of horizontal curves in railway construction are simple curves, compound curves, reverse curves, deviation curves, and transition curves.

Q: Where are compound curves used in railway construction?

Compound curves are used in railway construction to avoid cutting through hard rocks or excessive cutting and filling.

Q: What are summit curves and sag curves in railway construction?

Summit curves are vertical curves where a raising gradient joins a falling gradient, while sag curves are vertical curves where a falling gradient joins a raising gradient. Summit curves have convexity upward, while sag curves have convexity downward.

Q: What is the purpose of vertical curves in railway construction?

The purpose of vertical curves in railway construction is to facilitate changes in gradient and ensure a smooth transition between raising and falling gradients.

Summary & Key Takeaways

• Railway curves are geometrical arches that are provided when there is a change in alignment or gradient of a track.

• The functions of providing curves are to allow for gradual changes in direction, gradient, easy turning of trains, and passenger comfort.

• Curves are necessary in railway construction to bypass obstacles, provide easier gradients, avoid excessive cutting or filling, and avoid expensive land acquisition.