Engineering: Tube tunnels as alternatives to bridges for traffic

This ESL lesson plan is designed for intermediate to advanced learners (B1–C1) and centers on a fascinating engineering topic: the construction of immersed tube tunnels. Based on a transcript from Practical Engineering, the lesson uses an engaging real-world context to develop students’ listening, reading, speaking, and writing skills.

Through exploring how engineers build tunnels under waterways, students will expand their technical vocabulary, practice comprehension, and discuss innovative solutions to complex problems.

The lesson also encourages critical thinking about engineering challenges and environmental impacts, making it both educational and thought-provoking. By the end, students will not only improve their English proficiency but also gain an appreciation for the ingenuity behind modern infrastructure.

Immersed tube tunnels

Level: Intermediate to Advanced (B1–C1)
Duration: 60–90 minutes (You can reduce this time by having students prepare before class.)
Objective: Students will improve their listening, reading, vocabulary, and speaking skills while learning about immersed tube tunnel construction, based on the provided transcript.
Skills: Listening comprehension, vocabulary acquisition, speaking (discussion), reading comprehension, and writing.
Materials: Transcript excerpt (provided below), audio/video of the transcript (if available), whiteboard, handouts, access to a dictionary or online resources.

Lesson outline

Warm-up (10 minutes)

Objective: Activate background knowledge and introduce the topic.

• Activity: Discussion
  • Write the word “tunnel” on the board. Ask students:
    • What is a tunnel?
    • Have you ever traveled through a tunnel? Where?
    • Why do cities build tunnels instead of bridges?
  • Show a picture of a tunnel (e.g., an underwater tunnel) and ask:
    • How do you think engineers build tunnels under water?
  • Briefly introduce the concept of “immersed tube tunnels” as a unique engineering solution.

Vocabulary preview: Write key terms on the board (e.g., tunnel, bridge, harbor, prefabricated, watertight). Ask students to guess meanings or look them up.

Listening activity (15–20 minutes)

Objective: Develop listening comprehension and note-taking skills.

• Preparation: Use a shortened version of the transcript (below) or the video/audio of the Practical Engineering segment if available.
• Activity:
  1. Pre-Listening: Share a short excerpt (e.g., 1:45–3:31 from the transcript). Provide students with a handout of the excerpt with key words blanked out.
     Example Excerpt: One of the big problems with bridges over navigable waterways is that they have to be so tall. Building high up isn’t necessarily the challenge; it’s getting up and back down. There are limits to how steep a road can be for comfort, safety, and efficiency, and railroads usually have even stricter constraints on grade. That means the approaches to high bridges have to be really long, increasing costs and, in dense cities, taking up more valuable space. This is one of the ways that building a tunnel can be a better option… Immersed tube sections are built in dry docks or at a shipyard, where it’s much easier to deliver materials and accomplish the bulk of the actual construction work.
  2. First listening: Play the audio/video (or read the excerpt aloud). Students listen for the main idea without filling in blanks. Ask:
     • What is the main problem with building bridges over waterways?
     • Why are tunnels sometimes a better option?
  3. Second listening: Students fill in the blanks with the missing words (e.g., navigable, constraints, approaches, dry docks).
  4. Post-listening: Discuss answers as a class. Clarify difficult terms (e.g., “navigable waterways,” “constraints on grade”).

Key vocabulary

• Navigable (adj): Able to be sailed on by ships.
• Constraints (n): Limitations or restrictions.
• Approaches (n): Ramps or roads leading to a bridge or tunnel.
• Dry docks (n): A place where ships or tunnel sections are built or repaired out of water.
• Prefabricated (adj): Made in sections in a factory before being assembled on-site.

Vocabulary for extension

• Immersed (adj): Placed or sunk underwater.
  Example: The tunnel segments are immersed in the harbor to create the tunnel.
• Trench (n): A long, narrow ditch dug into the ground or seabed.
  Example: The tunnel segments are placed in a shallow trench on the sea floor.
• Dredger (n): A machine or vessel used to remove sediment or material from the bottom of a waterway.
  Example: A clamshell dredger excavates the trench for the tunnel.
• Buoyancy (n): The ability of an object to float in water or other liquid.
  Example: The tunnel segments’ buoyancy allows them to float before sinking.
• Gasket (n): A rubber or material seal used to prevent leaks between two surfaces.
  Example: Rubber gaskets ensure the tunnel segments are watertight.
• Backfill (n): Material used to refill a trench or space around a structure.
  Example: The trench is filled with backfill to secure the tunnel segments.
• Hydrostatic (adj): Relating to the pressure exerted by a fluid at rest.
  Example: Hydrostatic force helps seal the tunnel segments together.
• Sediment (n): Material, like sand or mud, that settles at the bottom of a waterway.
  Example: Soft sediment on the sea floor is not ideal for traditional tunnels.
• Couplers (n): Devices used to connect two objects, like tunnel segments.
  Example: Couplers pull the tunnel segments together during construction.
• Turbidity (n): The cloudiness of water caused by suspended particles.
  Example: Dredging can increase turbidity, harming aquatic life.

Reading and vocabulary (15–20 minutes)

Objective: Build vocabulary and reading comprehension.

• Activity: Provide a handout with another excerpt from the transcript (e.g., 4:38–6:00).
  Example Excerpt: Once in place, a tunnel segment is handed over to the apparatus that will set it into place. In most cases, this is a catamaran-style behemoth called a lay barge. Two working platforms are connected by girders, creating a huge floating gantry crane. Internal tanks are filled with water to act as ballast, allowing the segment to sink… In many cases, it’s just a layer of rock or gravel placed at the bottom of the trench, usually using a fall pipe (like a big garden hose for gravel) to control the location.
• Tasks:
  1. Students read the excerpt silently and underline unfamiliar words.
  2. In pairs, students use dictionaries or context clues to define words like:
     • Apparatus (n): Equipment or machinery.
     • Behemoth (n): Something very large or powerful.
     • Gantry crane (n): A large crane used for lifting heavy objects.
     • Ballast (n): Material used to stabilize or balance something.
     • Fall pipe (n): A tube used to place materials precisely underwater.
  3. Discuss as a class:
     • How is a tunnel segment moved into place?
     • Why is the construction process compared to docking a spacecraft?

Speaking activity (15–20 minutes)

Objective: Practice speaking and critical thinking.

• Activity: Small Group Discussion
  • Divide students into groups of 3–4. Assign one of the following discussion questions:
    1. What are the advantages of immersed tube tunnels compared to traditional tunnels or bridges?
    2. Why is the construction of immersed tube tunnels so complicated?
    3. What environmental challenges does this construction method create, and how can they be addressed?
  • Each group discusses their question for 5–7 minutes, then presents a summary to the class. Encourage use of new vocabulary (e.g., prefabricated, watertight, dredger).
• Teacher’s role: Monitor groups, provide feedback on pronunciation, and encourage elaboration.

Writing activity (10–15 minutes)

Objective: Practice writing and summarizing information.

• Activity:
  • Students write a short paragraph (100–150 words) summarizing how immersed tube tunnels are built, using at least 5 new vocabulary words from the lesson.
  • Example prompt: “Explain the process of building an immersed tube tunnel. Why is it different from traditional tunnel construction?”
• Homework option: Research a famous immersed tube tunnel (e.g., Øresund Link or Fort McHenry Tunnel) and write a short report (150–200 words) about its construction and importance.

Wrap-up (5–10 minutes)

• Review: Ask students to share one new thing they learned about engineering or tunnels. Write a few key vocabulary words on the board and quiz students on their meanings.
• Reflection: Ask
  • Why is engineering important for solving problems like crossing waterways?
  • Would you like to visit or travel through an immersed tube tunnel? Why or why not?
• Homework reminder: Assign the research report if not completed in class.