1. Manila folder bridges

2. MESA Bridge requirements
RULES FOR SIZE: Bridge Dimensions
1) Maximum length: 45cm
2) Minimum length: 42cm
3) Maximum Width: 10cm
4) Maximum height: 15cm
5) Minimum span: 40cm
6) Maximum mass: 60 g
RULES FOR CONSTRUCTION
1) Two-ply, legal-size, and press board file folders are not permitted. Only standard, light tan-colored, non-plastic, letter-size manila file folders are acceptable.
2) No part of the bridge shall extend below the support surface. (See diagram)
3) The load will be applied on the top of the bridge. The bridge therefore will not need a roadbed, since the test load will be placed on top of the bridge. .

3. 4) The top of the bridge must support a 10cm x 10cm plate which will bear the load for testing.
5) No material (e.g. paint, glue, varnish, hairspray, etc.) may be applied to the surface of the bridge to strengthen it. Ink or pencil to label the bridges is OK.
6) No bridge component may be completely coated with glue. Glue is restricted to the bonding surfaces connecting bridge components.
7) Completed bridge must have a mass of not more than 60g

4. JUDGING:
1) Prior to load testing, the bridge receives a specifications check to determine whether it conforms to the weight, dimension, and construction rules
2) The bridge is weighed and its mass recorded.
3) Bridges are judged for innovative design and craftsmanship by a team selected by the Host Center prior to testing. An award for innovative design will determined at that time.
4) Disqualified bridges may be tested in private, time permitting.

5. Awards are given in two categories:
1) Strength to Weight Ratio: Determined by dividing the maximum load by the weight of the bridge. The bridge with the greatest load bearing capacity compared to its weight wins.
Example: Maximum load = 60 lbs
Bridge weight = 55 g
Strength-to-weight Ratio
60lbs (454 g/pound)/ 55 g =
Three awards will be given to the first, second and third ranked bridges based upon the strength/weight ratio. These award winners will advance to MESA Day Finals.
2) Innovative Design: Bridges that display superior craftsmanship and design elements can win a first, second or third place award in innovative design. Winners in this category will NOT advance to MESA Day Finals.

6. Tips for building
After a design has been decided on here are some tips for construction of the bridge.
1) make the full size design on a large piece of graph paper
2) cover the graph paper with wax paper and tape all this to foam board or cardboard so you can use pins to set the pieces in the right places
3) square members are the strongest so you have to measure the length of members you want onto the manila folder and then make to width five times the size you want, and add a little to the ends for gluing to the next member.

7. After you have the member cut out measure five equal sections and score the lines you will bend the folder paper at with the back of the knife or another dull object, this will help the paper bend where you want it to. Then fold and glue into a square shape
When you have all the members cut and folded use your graph paper covered with wax paper to connect all the pieces together for one side the repeat for the other side. Then make a glue to supports between the side to finish the bridge.