BuiltWithNOF
Bridges

See also the ‘roll tube structures’ page

eden_0003_470x353[1]

Bridges are really important structures. We usually take them for granted but we find it impossible to do without them.
This was found to be the case when the Cumbrian Floods took place in the winter of 2009-10.

article-1229466-074C156C000005DC-662_634x392[1]

Some bridges were swept away or so badly damaged that they had to be taken down. Sadly, lives were lost in the tragedy.

article-1233807-0779E410000005DC-905_634x400[1]

New bridges had to be built as quickly as possible because whole communities were cut off from friends, families and their places of work. A journey which took 5 minutes across the bridge now took hours of traveling by car, bus or train to go all the way round by another route.

1201606913[1]

The Army Engineers stepped in to build this bridge in Workington. It is called a Bailey Bridge and was designed for use in the Second World War to replace bridges quickly which had been bombed and destroyed in battles.

article-1233807-0780DD20000005DC-860_634x432[1]
article-1233807-07815A9A000005DC-33_634x380[1]

How did they build a bridge across a wide river without holding it up in the middle? Surely it would just collapse before it was finished?

Perhaps you could research this and work out how they did it!

Designing your own bridge and making it from paper roll tubes is great fun and the bridges are incredibly strong yet weigh very little!

Look at these pictures of roll tube bridges made by Primary and Secondary school students.....

4-2-11 001a
3-3-12 028a
15-2-11 030a
26-5-11 050a
26-5-11 053a

Sydney Harbour Bridge

Design for an arched footbridge.

This model is 2metres across!

Left: a very long girder bridge.

Right: The Tyne bridge Newcastle. It is similar to the Sydney harbour bridge but they are not copies! Which one was built first?

Left: A model of the Stephenson Bridge (High Level Bridge) Newcastle.

Right: A model of the Metro bridge Newcastle. One half has almost been completed!

Left: A model of the Armstrong Swing Bridge Newcastle. It rotates through 90 degrees to allow ships to pass.

Right: A WWII scene featuring a Bailey bridge over a river.

1-2-11 037a
16-3-12 008a
26-5-11 044a
26-5-11 051a
Caedmon Primary 016a

Do you have a favourite bridge?

These are my favourites. Do you know what they are called and where they are?

tyne bridge bw
TAY_1_063i

Bridge Design and Construction

These pictures show a group of Engineering and Art and Design students taking part in a Work Related Learning Activity. The challenge involves finding out how a bridge works then deciding which type of bridge might suit a particular need or set of conditions. Students then build various bridges and test the strength as well as come up with new concept bridge designs like the Gateshead Millenium bridge over the River Tyne.

YA0006

click this picture

This group are sketching bridges which they have seen before. They go on to find out why there are so many different bridge designs and then produce a new concept bridge.

A basic set of tools and workbench are required. The bundle of aluminium strips was used to make the girder bridge bottom left.

How does a suspension bridge work?
Let’s build one and find out!

Manufacturing and Product Design Diploma

YAweb0003

This aluminium strip girder bridge was tested and held an amazing 29 house bricks - considerably more than the weight of the bridge itself!

Plastic conduit was used to construct this arch bridge which was then modified so that the inner structure folded away to allow ships to pass under

YA0007
YAweb0001
YAweb0002

Other bridge modeling materials and methods

Tower and beam bridges

Copy of 10-8-13 00202
Copy of 10-8-13 005
Copy of 10-8-13 006
22-5-12 022

All sorts of materials have been used to model bridges. Even spaghetti (uncooked) can be glued together to make some amazing girder bridges which are very light yet very strong.
 

The simplest materials to use are paper and card.
 

These techniques can be used with very young children eg. 4-5 yrs old and can result in some excellent products. They also allow the children to have a go at ‘problem solving’ eg. how to cross a river, road, valley or uneven terrain where a level road is desirable.

This method is also very inexpensive and children could take home part of the bridge eg. two columns ( paper cylinders) and one beam (made from a folded card strip which acts as a road deck also)
 

These columns are simply paper cylinders held in shape with pieces of tape or glue.
 

A cylinder like this is incredibly strong yet it only weighs a few gramme. Try resting books carefully on top of an upright paper cylinder - it’s amazing how many it takes to buckle the cylinder!
 

Try using A5, A4 and A3 paper in landscape orientation so that a wide cylinder is obtained because smaller diameter cylinders aren’t very stable.
 

The ‘beams’ resting on top of the columns are made from card strips which have been folded up at the edges to increase their strength and stop them from bending! This is an important technique used to strengthen real construction materials such as metal corrugated roof sheets.
 

It also makes the beams look like road decks ideal for testing by adding model cars!
 

The floor could be laid out with scenery such as roads, railway lines, rivers and mountains. The children are challenged to route a roadway through the terrain but to try and keep the slope of the road to a minimum. This can be done on a large scale and several classes can be involved at the same time in a large room or school hall. It’s great fun and involves all sorts of skills including teamwork and basic practical skills in shaping, sticking and folding paper and card.

Tubular girder bridges

Copy of 10-8-13 015
Copy of 10-8-13 019

Older children (yr 1 and 2) can make some fabulous structures with rolled up sheets of newspaper.

The rolls are about 40cm long and are made using a piece of plastic water pipe (about 3 to 4cm diameter) as a former. Once the tightly rolled tube has been formed and taped the plastic tube is removed.

Lots of paper tubes are needed and ‘production teams’ can be set up with children working together to make as many tubes as possible in a given time. The children are allowed to organize themselves and evaluate performance then change their production method to try and improve quality and speed up production.

The tubes can be joined together using tape and the corners can be strengthened using card. All sorts of large shapes, structures, buildings etc. can be made using this method. Additional paper and card can be used to make walls etc.

Huge bridges can be made by a whole class working together and it’s a great way to learn about shape, strength and stability of structures eg. by building the tallest possible tower or longest possible bridge across a gap.

Copy of 14-9-13 035 Copy of 14-9-13 066

Here a road deck has been constructed using three long paper tubes with some card folded around them. The deck can sit on top of simple paper or card towers. Then an additional piece of card is folded so that the long edges stick up vertically to form a barrier either side of the road. The three tubes make a structure called a box girder (very like a real ‘beam’ in a common bridge found crossing over our motorways) - perhaps we should call it a tube girder!

Copy of 14-9-13 072 Copy of 14-9-13 076

A tubular girder bridge. Year 1 and 2 might find this a lot more difficult because various lengths of tube are needed to strengthen the basic structure of 2 long and 4 shorter tubes. The final picture shows a string which has been added to take some of the ‘load’ from the centre of the deck. This string is called a ‘stay’ so we might call the bridge a ‘cable stayed girder bridge’.

30-9-09 014
14-10-10 012

Children from year 2 upwards can make tightly rolled paper tubes (called ‘roll tubes’). They are extremely versatile units or elements from which all sorts of structures and mechanisms can be constructed.

We can think of them as ‘girders’ used in the construction industry and set all sorts of challenges using them as the basic building blocks.

Sometimes real metal nuts and bolts are used to join them together but a quicker way (which is also easier to disassemble) is to use wooden dowels as crosspieces to connect the tubes together.

Roll tube scan be used to design and make.......

bridges, cranes, vehicles, shelters, stadiums, gliders, rockets, fairground rides, playground structures etc. etc....

They are very versatile!

roll tubes etc 012a

The wooden dowels used in paper roll tube structures can also act as axles for rotation. This allows us to introduce mechanisms into our structures as in cranes and lifting bridges.

There are lots of wooden and steel girder lifting bridges in Holland because there are so many canals to cross. Some are counterweighted so that a single person can wind the mechanism to make them lift and fall with ease.

Below right is a lifting bridge across a canal at Edam in Holland.

13_big[1]

This is the River Tees ‘Newport’ lifting bridge. The whole road deck lifts vertically on cables from both ends so that ships can pass underneath.

1450_11_5_web[1]
22-5-12 021

Plastic straws can also be used to build bridges.

A gadget called a ‘toobz machine’ can be used to cut and punch the straws accurately. This allows for highly symmetrical structures because the lengths of the straws can be controlled precisely.

I have used the ‘toobz’ method of construction with year 2 children and above. Year 4 and above can cope with using the toobz machines but lower years than this are better off being supplied with precut and punched straws.

22-5-12 019
Copy of 10-8-13 00702
Copy of 10-8-13 009
Copy of 10-8-13 010
22-9-13 032b

Corriflute or correx is a very strong construction material but it takes special tools to work it ie. to punch and cut accurately. It is made from two layers of very thin plastic sheet with corrugations or ribs in between holding the sheets together.

The thin blue strips have been cut using a craft knife and safety rule on a cutting mat prior to the lesson. It is tough to cut and their are major safety issues even up to year 6. If precut and punched strips are used then this technique of bridge building can be used with year 2 upwards.

The strips are great to work with and can be held together by using small elastic bands at the ends. They can also be hot glued and if punched can be ‘click riveted’ together using small plastic rivets which are pushed in by hand (see below).

Simple card templates or guides can be used when positioning holes accurately in the ends of the strips. The holes are made by a punch as shown.

A great way to join the strips together in a structure is to use wooden dowels as with the paper roll tubes.

The great advantage of wooden dowels as the method of fastening is that the structures can easily be modified and designs changed without any great loss that would occur if the structure was glued.

Corriflute strip is brilliant for making robust structures and mechanisms such as bridges or fairground rides which move using winding mechanisms, pulleys, electric motors or syringes containing air or water.

Making corriflute structures takes more preparation than other types of construction method and is more expensive than the simpler paper and card methods.

There is a special type of fastener called a ‘click rivet’ which provides an alternative method of fastening the corriflute strips together. The rivets are in two parts - the ‘rivet’ itself which is like a nail with a head but without a point, and the retainer which is like a ‘nut’ which is a tight push fit onto the end of the rivet.

A hole has to be made through the strips first and this is best made using a thin pointed wooden dowel. If a conventional metal hole punch is used the holes tend to be too big and the joints tend to be slack.

22-9-13a 006a

This girder bridge uses 14 identical length strips for the two side structures and 4 or 5 cross pieces to support the road deck. With so many strips held by each rivet it can be difficult to get them all to fit!

22-9-13a 007a

Using a corriflute road deck in the model means that fewer strips are needed. The rivets pass through into the hollows in the red corriflute sheet which forms the road deck.

Click rivets can be very useful for moving levers and mechanisms. The retainer can be fitted a little more loosely to allow motion of two connected strips. The small parallelogram of strips in the picture is able to move so as to alter the angles.

Remember! Children can find it difficult to cut corriflute and safety issues must be considered if saws and craft knives are to bve used. When I use it I usually prepare a lot of strips which can be cut to length easily with scissors. On other occasions it useful to have stock lengths and widths so that there is a basic choice but no cutting required. Punching holes and making holes with pointed dowels is a safe operation for children in year 4 and above.

XL_BALSABRIDGE[1]

Balsa or strip wood can be used with great effect in making structures.

All sorts of practical skills can be practiced eg. using measuring, templates, saws, saw blocks, mitre block for angles, wood glue, hot glue, nails as fasteners etc. etc.

A bridge building challenge could involve costing the materials and estimating the cost of the bridge then working out how strong it is and producing ratios of strength to weight and strength to cost so that various bridges can be compared.

Wood is very versatile in that it can be cut to the sizes required with simple tools and joined strongly with glue. The final structure is permanent and the only way to properly test it could be to destroy it by adding weights, though it can usually be repaired!

A paper or card bridge template for a wood strip bridge

bridges woodstrip 015

Wood strip bridges can present a big constructional challenge as it is easy to introduce inaccuracies in the positioning of each member added to the structure. The inaccuracies grow as the structure gets bigger and a very uneven final bridge structure can result.

One way to make sure that the members line up is to draw a basic paper plan and glue the pieces to the paper!

Before gluing it’s important to have though it through because you may have to fold the paper with the parts stuck to it. Here is an example....

bridges woodstrip 012

The above bridge started off as a sheet of paper with guidelines drawn onto it to help position the flat wood strips. The strips are of two lengths and are hot-glued in place one at a time to create the mirror image sides of the bridge.

bridges woodstrip 013

The sides are then folded up at right angles to face each other and the horizontal deck strips are then glued in place. The structure starts of 2D and after folding becomes 3D. The paper can be removed using scissors or a craft knife (safety permitting) or can be left in place as above. This method of construction is less fiddly than creating a structure piece by piece in 3D.

bridges woodstrip 01402

The above pic shows 4 of the members glued in position. The next step is to create the triangular sides. Next the two sides are folded in at right angles to the base so that they face one another. The cross pieces are then glued in. Excess paper has been trimmed off.

bridges woodstrip 018

This bridge is ready to have a card road deck added.

bridges woodstrip 019

The arch shown left was made using a paper plan. The strips were placed one at a time on a curved line drawn on the paper and another overlapping layer glued on top.

The next step would be to create an identical arch and then glue horizontal connecting strips between the two arches which could support the road deck.

All sorts of structural shapes are possible using the wood strip and glue method.

IMG_1922a

Amazingly strong girder bridges can be built using aluminium strips. The strips are cut and punched to exactly the same lengths and this results in highly symmetrical structures which share out evenly the forces experienced when the bridge is ‘loaded’. The bridges are tested using bricks as weights - wrapped to cushion the fall!

IMG_1938a

One of these bridges held 86Kg which is the weight of a large adult!

Pages coming soon...

Suspension Bridges

and

Bridge Types

All of the bridge construction methods can result in a fantastic finished product which students can be proud of! It’s a question of choosing the method which suits a particular age group and can provide a good challenge but result in a pleasing outcome at a reasonable materials cost.

More ideas coming soon!

[Technology Tom] [2015 Eclipses] [Boxed Kits for sale] [Resources for sale] [INSET] [Science shows] [Science] [D and T Projects] [Stadium Project] [2012 Stadium] [Management] [Stadium Kit] [Stadium Competition] [Stadium Files] [Spinner Game] [Playground Structures] [Vehicles] [Solar Powered  Car] [Balloon Powered Vehicle] [Land Yachts] [Torches] [Coloured gel puppets] [Pneumatic Monsters] [Buzzer Games] [Cams and Cranks] [Fairground Rides] [Rockets] [Motor Projects] [Helicopters and Fliers] [Silver Swan] [Leaning Tower] [Magnetic Games] [Dodgem Cars] [Winding things up] [Wind Power] [Water Power] [Hydraulic Crane] [Roll Tube Structures] [Bridges] [Bridge Types] [Suspension Bridges] [Forces in bridges] [Bridges intro] [Woodstrip Bridges] [WW2 Structures] [Ancient Britons] [Pirates] [Cutty Sark] [World War 1] [Aztecs] [Moon Buggies] [Ballista catapult] [Viking Ships] [Viking ship model] [Boats] [Morse Code Buzzer] [New Wear Bridge] [Land Yachts 2] [New Projects] [Try this] [Basic vehicle assembly] [MPD Diploma] [Workshops] [Libby] [Christmas Lecture] [queries page] [Raspberry Pi] [HMS Belfast] [Tree Houses] [Andrew] [Gainsborough Primary School] [Path Head Watermill]