Bridges and tunnels

Learning objectives

Pupils should be able to:

recognise different designs of bridges
understand that bridges are built for specific purposes
know that bridges fulfil design, function and safety in construction, and therefore are maintaining Standards
follow a set of instructions to create an object and then employ critical evaluation
use the internet or reference books to research topics.

Vocabulary

Civil engineer is someone who plans, designs and supervises the construction of projects.
Construction manager is someone who coordinates the building process of a project from start to finish.
Span is the distance the bridge extends between two supports.
Structural engineer investigates the behaviour and designs of all kinds of structures to make then safe.

Cross-curricular links

Literacy, Numeracy, Geography, Science, Design and Technology, ICT, History, Art.

View the Scottish Curricular Map

Resources

Standards for bridges

The following are all areas in which Standards can be applied to the design and construction of bridges. They may be used to provide appropriate ideas for pupils when thinking about designing their own bridge.

Design

Design of steel bridges, for example length and width of vertical (supporting) and horizontal (resting) beams, strength of joints
Design of concrete, for example length and width of vertical (supporting) and horizontal (resting) beams, strength of joints
Design of timber structures, for example length and width of vertical (supporting) and horizontal (resting) beams, strength of joints
Design structure for earthquakes, fatigue
Design of road lighting

Materials

Strength and durability of steel bridges
Strength and durability of concrete bridges
Materials and workmanship

Safety

Safety fences and barriers
Highway parapets for bridges and vehicle containment
Pedestrian and vehicle restraint systems

Load

Traffic loads such as cars, trains, people, for example the new Millennium Bridge in London
Bearings, for example joints such as draw bridges and tilt (the new tilting bridge at Gateshead) and parts that need to slide.

External forces

Thermal performance, for example sun and snow
Mechanical vibration
Wind action
Earthquakes

Starter

Show pupils pictures of a range of different bridges including some that they may already be familiar with, for example the Golden Gate Bridge, Sydney Harbour Bridge, the Iron Bridge, or the Millennium bridges – Gateshead and London, As a class, discuss how bridges are built and made. Ask pupils what sorts of Standards they think bridges may need. Think about what bridges need to do, for example support people and cars, and record all ideas on the board.

Further information on Engineering innovation: Bridges and tunnels.
(File type: Adobe Acrobat document, File size: 398.01kb)

Teaching sequence

Activity 1 – Give pupils Activity sheet 1 and ask them to match the picture of the bridge with the descriptions provided, to enable them to become familiar with different types of bridges. This will include information on their appearance, span, cost-effectiveness, means of support, materials and their function.

Solutions to the ‘How well do you know your bridges?’ exercise:

Arch bridge is the oldest type of bridge. It has excellent natural strength because weight is distributed along the curve of the arches. It spans between 60–250 metres. An example of an arch bridge is the Sydney Harbour Bridge in Australia.
Cable-stayed bridge is attractive and modern looking. It spans between 150–850 metres. It is built quite quickly and is cost-effective. The bridge is supported by cables, which are all attached to towers and to the road at regular intervals in various patterns. The new Sundial Bridge crossing the Sacramento River at Redding, California, is an example of a cable-stayed bridge.
Girder bridge has a basic design and is the most affordable. Piers on either end support the horizontal beam. The weight rests on these piers. It is not very high, so ships are unable to pass under it. Many motorway flyovers and railway bridges are examples of girder bridges.
Suspension bridge is the most expensive bridge to build, but it is the lightest and most attractive. The sides are anchored down and the cables help distribute the weight evenly. It spans between 600 – 2000 metres. An example of a suspension bridge is the Golden Gate Bridge in San Francisco.

Pupils should then be encouraged to use the internet and/or reference books to research information on a number of famous bridges, listed below. This will help them to become more familiar with different types of bridges. Can they see how, if Standards are not maintained for all bridges, disasters may occur?

Discussion points plus key bridge builders

The Tay Bridge disaster: what happened? – In 1879 the bridge collapsed into the Firth of Tay at Dundee, Scotland and 75 people died as a train travelling across it plummeted into the river. The bridge had only been open for 19 months when the iron columns supporting it collapsed into the water. The iron was of a poor quality and had cracked in the cold weather.

Why is the original London Bridge now in Arizona, USA? – It was bought by an Arizona businessman in the 1960s for $2.4 million and reconstructed in Lake Havasu City.

Who was Isambard Kingdom Brunel and why is he famous? – He designed Paddington Station, Bristol’s Clifton Suspension Bridge and a network of tunnels, bridges and viaducts for the Great Western Railway. He was also responsible for the famous bridge over the Tamer at Saltash near Plymouth.

Where is the longest bridge in the world? – The Akashi Kaikyo Bridge in Japan is the longest suspension bridge in the world and spans three-quarters of a mile. Construction began in 1988 and it took 10 years to complete.

Activity 2 – Ask pupils to now think now about building their own bridge in the classroom. To prepare they will need to think about which Standards will be important when designing their bridge, for example weight of traffic crossing the bridge, location of the bridge, materials the bridge is made from, will the bridge need to withstand particular weather conditions. Further information on Standards applied to bridges can be found at the beginning of these notes. In pairs, pupils should brainstorm the Standards they wish to use for their bridge and then record them on Activity sheet 2, ranking each factor in order of importance.

Activity 3 – Provide pupils with the materials to build their own paper bridge, and see how great a load it can support. Each pair will require:

Sheets of A4 paper
Two school desks brought alongside one another
A few paper weights
A ruler
Unifix cubes, toy cars

Using Activity sheet 3, pupils should follow the instructions and build their bridge. Can they think of ways to improve its stability?

Plenary

Pupils evaluate their constructed bridges, using the prompts and Standards as a guideline of what is expected, to see if all the requirements they decided upon were met.