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Updated on 12/2/2020

BBC Specifications and Rules

The main structure of the bridge must be constructed only of wooden Popsicle sticks and white glue. Construction paper is only to be used for the deck of the bridge, which can be cut to fit the design of the bridge.

  • The only construction materials allowed are:
  • Regular white all-purpose glue
  • Standard wooden Popsicle sticks
  • Construction paper

NOTE: Refer to Picture 1 for an example picture of white glue and Popsicle sticks

Your bridge MUST conform to following specifications:

See Figure 1 and Figure 2

Fig 1

L is the overall length of the bridge – Minimum 550 mm and Maximum 700 mm. A is the portion that may be below the supports and should be less than 500 mm. (Exceeding 500 mm will make the bridge to rest on this portion below the main bridge structure and will not rest properly for testing. So keep this dimension less than 500 mm.

The total weight must not exceed as follows:

Senior Category -250 grams.

Junior Category - 300 grams

 Your bridge must rest steadily on two supports of the testing machine. The clear distance between these two supports is 500 mm.

Design your bridge long enough not to slip or fall through this span under load. Remember that materials bend when loaded (we suggest a minimum bridge length of 550 mm).

The travelled portion of your bridge must be at least 60 mm wide, capable of transporting two matchbox cars (each car’s dimensions are approximately 30 mm wide x 70 mm long x 30 mm high). Both cars must be able to roll smoothly across the bridge deck in both directions simultaneously. 

1. The maximum length of the bridge must be less than 700 mm.

2.The maximum width of your bridge must be less than 150 mm.

3. Your bridge structure may project up to 200 mm above the top of the supports.

4.Your bridge structure may project up to 50 mm below the top of the supports.

Provision must be made to allow the loading platform with bolting attachment (132 mm long x 50 mm wide x 12 mm high) to be positioned at the centre of bridge span at the competition site.
At the centre of the bridge, a vertical clear space 15 mm in diameter free of sticks must be maintained for the bolt, nut and washer to apply a test load. Look at photographs in
Picture 2 of the bridge testing machine and Picture 3 for the loading platform

The paper deck should be continuous. If needed, a hole for the loading platform bolt will be drilled at the competition site.

The Popsicle sticks can be cut and/or shaped in any way and may be coloured.

If the Popsicle sticks have to be cut, trimmed or drilled, then this should be done using tools that are designed to be safe for children to use and under the direct supervision of a teacher or another responsible adult.

Cut pieces may be used as pins in joints.

To qualify, your bridge must be tested before you arrive at the competition.  

We require an adult to certify that your bridge has been tested and can support at least a 4kg load.
(Note: past winning bridges supported over 25 times this load)
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Please test your bridge early so that you have time to fix any problems you find.

A suggested method of load testing is described in section 6 below.

  • Attach a paper tag to your bridge, on which you have clearly written your bridge name and the names of your team members.
  • Finally, think, plan ahead and be patient… good bridges take time to build. (and glue takes time to dry!)

Judge’s Criteria 

Each bridge will be judged for the following five attributes:

  • Construction technique
  • Construction quality
  • Technical presentation and description of your bridge design process
  • Aesthetics
  • Creativity

NOTE: Doubling popsicle sticks - that is sandwitching by applying glue over the length of stick and sticking another popsicle stick over the other is Not acceptable and will be disqualified. 


 

Number of layers of Popsicle Stick glued together forming a solid block of lumber.
NOT Acceptable


In the event of a tie, results of Post Destructive Analysis (See after Destructive testing) will be used for the particular cases to decide on the winners.


Destructive Testing 

The bridge inspectors will ensure that each entry complies with the rules.
Only bridges that conform to all the specifications will be accepted.

NOTE: Bridges not meeting the specifications will be disqualified.

Bridges will be weighed before the destructive test.

The load will be applied from below at the centre of the deck by the loading platform.

Testing will consist of the application of an increasing load via the loading platform by the bridge testing machine, until the bridge breaks, or flexes by maximum of 50 mm (whichever is earlier). A visual warning will be indicated by a red lamp on reaching 50 mm deflection. The peak load recorded up to this point will be considered the breaking load.

The winning entry will be the bridge with the highest performance rating.
In the event of a tie, the lightest bridge wins.
It is up to your team to decide on the optimum balance between mass and strength.
Performance rating = (Breaking load) (Unloaded weight of your bridge)
i.e. the bridge that carries the largest load may lose to a lighter bridge. See last year's results!

Be aware that all bridges will be destroyed during testing!!!

All decisions of the judges are final.


Post Destructive Analysis

After destructive testing, expert Engineers will analyse the bridge with the contestants, with a view of education and to check the analytical capabilities of the contestants and marks given. These marks may be used for decision in case of ties.

How to Test   

  • Make a pencil sized hole through the centre of your bridge.
  • Make a loading platform to distribute the load on your bridge. (See figure 3 for an example)
  • Tie a piece of rope to the centre of your loading platform.
  • Thread the rope through the hole you made in the centre of your bridge.
  • Tie a plastic grocery bag to the other end of the rope.
  • Place two tables 500mm apart. These will be used to support your bridge.
  • Place your bridge on the tables with the plastic bag hanging below the bridge.
  • Place a 2kg bag of sugar into the plastic bag.
  • If your bridge looks strong enough, add a second 2kg bag of sugar.
  • Congratulate yourself for passing the qualification test.

Picture 1:White glue and a packet of 200 Popsicle sticks

Sold as "Craft Sticks" (or equivalent) - Neutral colour preferred.

Coloured sticks also available and acceptable):

 11.43 cm x 0.96 cm x 0.15 cm (4.5" x 0.38" x 0.06")

 6.35 cm x 0.96 cm x 0.15 cm (2.5" x 0.38" x 0.06")

Remember that Popsicle sticks vary in density. Glue and paper add significant weight. Ensure that your completed bridge is not overweight.

NOTE: Glues such as "Super Glue", "UHU", "Araldite", "Gorilla Glue" etc. etc. are unacceptable and use of such will disqualify the bridge


Picture 2: A bridge on the Bridge Testing Machine

Take careful note of the supports that your bridge must rest upon. The clear distance between these two supports will be set to 500 mm within a tolerance of  1mm.
The load is applied at the centre of your bridge with a bolt that pulls from below.
Your design must allow space for this bolt to pass through the bottom of your bridge.


Picture 3: Loading Platform attached to a bridge

The bolt that applies the load goes through the loading platform. A washer and nut secures it. The loading platform distributes the load on your bridge.

Bridge on support Bridge on support Bottom view

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