---
title: "Suspension Bridges: cables"
subject: "Communication English"
chapter: 2
key: "semester_5/communication_english:suspension-bridges-cables"
source: https://www.bctengineer.com/q/semester_5/communication_english/suspension-bridges-cables
site: BCT Engineering
---

# Suspension Bridges: cables

Communication English · Chapter 2: Extensive Reading

- Asked in: 2071 Shrawan, 5 marks
- Video: [What are Suspension Bridges? explained in 4K || 3D Model with Components](https://www.youtube.com/watch?v=cXq0i3CDumg) — BridgeHAWK®
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/communication_english/suspension-bridges-cables
- Whole chapter: https://www.bctengineer.com/md/semester_5/communication_english/chapter-2

## Question

How are cables constructed and used in suspension bridges? (Suspension Bridges)

## Short answer

Cables are made of thousands of high-strength steel wires spun across towers, bound into a single round cable, and protected against corrosion. They hang in a curve, anchored at ends, and support the deck via vertical suspenders, transferring loads as tension to towers and anchorages, enabling very long spans.

## Answer

In a suspension bridge the deck is hung from large cables which are the main load-carrying members. The cables are made of steel wires and are arranged and fixed as follows.

#### Construction of cables
1. **Wire.** Thousands of high-strength steel wires, each a few millimetres thick, are used. Steel wire carries a very high tensile load.
2. **Spinning.** Wires are drawn across from one anchorage to the other, over the tops of the towers, one by one or in groups (strands), and are adjusted to the same tension and curve.
3. **Bundling.** The wires or strands are bound together into one round cable, tightly compressed, and wrapped with wire to protect against rust.
4. **Protection.** The cable is coated and sealed against water and corrosion.

#### Use of the cables
```text
     |tower                  tower|
    /|\                    /|\
   / | \ main cable       / | \
  /  |  \_______________/  |  \
 /   |  |  |  |  |  |  |   |   \
anchor  suspenders (hangers)  anchor
=========== bridge deck ===========
```
- The main cables hang in a curve between two towers and are firmly anchored at each end in massive concrete blocks or rock.
- Vertical wire ropes or rods called **suspenders** or **hangers** connect the cable to the deck at regular distances and carry its load.
- The weight of the deck, vehicles and wind loads is transferred to the cables as tension, and from them to the towers (as compression) and the anchorages.

This design allows very long spans, which is why suspension bridges are used over wide rivers and gorges.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What are the main cables made of?
   A. Concrete strands
   B. Timber ropes
   C. Thousands of high-strength steel wires
   D. Single thick steel bars
   Answer: C. Steel wire carries very high tensile load. (Key point: Material)

2. How are the wires placed?
   A. Drawn across from anchorage to anchorage over the towers and adjusted to equal tension
   B. Cast in place
   C. Welded on the deck
   D. Hung only from the deck
   Answer: A. They are then bundled and wrapped. (Key point: Spinning)

3. What is the role of suspenders (hangers)?
   A. Anchor the cable in rock
   B. Protect the cable from rust
   C. Connect cable to deck and carry its load
   D. Support the towers
   Answer: C. They are vertical ropes or rods at regular distances. (Key point: Suspenders)

4. How does the load travel?
   A. Deck load becomes tension in cables, then compression in towers and force on anchorages
   B. Compression in cables and tension in towers
   C. Directly into the water
   D. Only into the deck
   Answer: A. Anchorages are massive concrete blocks or rock. (Key point: Load path)

## Related in other subjects

- [Bheri river suspension bridge collapse](https://www.bctengineer.com/question.md?key=semester_8%2Fengineering_professional_practice%3Abheri-suspension-bridge-collapse) — Engineering Professional Practice, chapter 7
- [Suspension 200 m: max/min tension, cable length](https://www.bctengineer.com/question.md?key=semester_4%2Ftheory_of_structures_i%3Asuspension-200m-dip20-3x800kn) — Theory of Structures I, chapter 7, asked 3×
- [Suspension 100 m: max/min tension, SFD, BMD](https://www.bctengineer.com/question.md?key=semester_4%2Ftheory_of_structures_i%3Asuspension-100m-dip10-3x200kn-dead-40) — Theory of Structures I, chapter 7, asked 3×
- [Suspension 400 m: max/min tension, cable length](https://www.bctengineer.com/question.md?key=semester_4%2Ftheory_of_structures_i%3Asuspension-400m-dip30-3x300kn) — Theory of Structures I, chapter 7, asked 3×