Bridges are one of the most useful and magnificent structures of the modern civilization. With ever improving designs bridges carry immense loads daily and are expected to survive for years on end. Not only that the bridges should also be able to handle incidental loads due to natural calamities.

Task

We bring you the challenge to design a bridge over a valley using Tooth picks, Popsicle sticks (ice-cream sticks), White glue and Thread which can sustain maximum load, satisfying the stated constraints.

Cash prizes worth INR 24,000 to be won.

Download the Problem Statement.

Specifications updated on the website.

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Last date for registration is extended to 31st December,2011

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Bridge Specifications

Construction of a bridge involves sequential construction of three components i.e. towers, anchorages and deck structure.

Anchorages:

Anchorages will be provided by the organisers. They will be C-shape channel sections 210 mm high and the distance between these C-shaped channels will be 1300 mm. The extended part of the deck beyond the two towers will be joined to these anchorages using 4 clamps, 2 on each side. Clamps will be provided by the organisers.

Towers:

1. The tower of the bridge will be required to lower into a groove of area 80mm X 80mm having a depth of 50mm.
2. One tower groove is at the height of 100mm from the base and the other groove is on the base of the board.
3. The distance between the two towers (measured centre to centre) should be 1000 mm (Refer Figure).

Deck Structure:

1. The maximum length of deck of the bridge can be 1400mm.
   Penalty: -5 points for length greater than 1400mm.
2. The minimum width of deck of the bridge at any point must be 150mm.
   Penalty: -5 points for width less than 150mm.
3. The maximum width of the bridge at any point must be no more than 250mm.
   Penalty: -5 points for width over 250mm.
4. The elevation of the operating surface(the flat road surface) of the deck from the ground should not exceed 230mm.
   Penalty: -5 points for deck height over 230mm.
5. A 400mm X 400mm X 150mm(height) box will be passed underneath the middle of the bridge.
   Penalty: -5 points for failure of the box to clear the structure.
6. The maximum height of the bridge (from the ground to the tallest point) must not exceed 600mm.
   Penalty: -5 points for height over 600mm.
7. All the cables (if used) in the bridge will be made up of single layer of string. Use of multiple layers of strings is not allowed.Only one string can be used between any two points on the bridge.
8. Strings can either be glued to the deck or you can knot the string to the popsicle sticks. No two popsickle sticks can be bonded using strings.
   Penalty: -10 points for this.
9. The load will be applied on the deck of the bridge. A clear opening of at least 100mm X 200mm must be maintained above the centre of the bridge deck so that loads can be kept at the centre point of the deck.
10. The length of the bridge extending out of the centre of the towers to the centre of the anchorage will be 150mm on each side of the towers.(refer fig)
11. A smooth continuous bridge deck for vehicular traffic must be provided along the entire span of the bridge. It must run the entire length of the bridge. The continuous deck must be constructed by using popsickle sticks and toothpicks (i.e. no solid glue decks).
    Penalty: -25 points for a nonconforming deck. This penalty is particularly severe, since a road bridge without a deck is rather pointless.

NOTE : The entire structure of the bridge should be rested ONLY on the top surface of the anchorage and the towers should be lowered in the groove. No part of the bridge should touch any other part of the plot provided by the organizers apart from the above mentioned.

Plot Specifications

1. Two wooden channel sections will be provided as shown in the figure. The centre of the wooden section will be 1300 mm apart.
2. A total of 4 clamps will be fixed 2 on each of the two sections. Your extended deck will be supported by these clamps with the help of one single string for each clamp.
3. The tower structure of the participant’s bridge will be mounted on the 2 zones shown in blue and green. Each zone is 80 mmx80 mm with a depth of 50 mm. Distance between the centres of the two zones is 1000 mm. They are placed 150 mm respectively from each channel section. The height of blue section is 100mm from the base and the other is on the base. The board will be provided by the organisers.

Material Constraints

1. Popsicle sticks (maximum length 110 mm, width 13 mm and thickness 3 mm), wooden toothpicks (maximum diameter 2 mm, length 65 mm and non coloured), threads (cotton only, synthetic material threads will be disqualified) and adhesives (Synthetic white adhesive or single component cyano-acrylate adhesive) can only be used to build the structure.
2. Adhesive can only be used to join Popsicle sticks and Toothpicks together; however adhesives cannot be applied on the free surface of a member made of Popsicle sticks to increase its strength (Adhesives such as M-Seal® are not allowed).
3. The maximum diameter of a string member that can be used is 1 mm. Suggested string is the cotton string used by cobblers. To verify this constraint each team must bring a 1 m long sample of the string used by them. (To verify the diameter of the string, it will be wound about a cylindrical object (like a pen). 10 turns will be wound about a cylindrical object. The length of the string will be measured along the axis of the cylinder. Thus the diameter of the string would be equal to the length of the string along the axis of the cylindrical object divided by number of turns wound about it.)
4. The Popsicle sticks and Toothpicks can be cut or trimmed to any shape or size.
5. Structures built using any other materials except those mentioned above will be disqualified.

Test Condition

1. Prior to evaluating the bridge, the dead weight (m) is measured and recorded in grams and the teams have to predict the ultimate load carrying capacity (Fp) of their structure.
2. The team members will decide how much weight should be kept initially on the bridge(minimum weight 10 kg). The weights will be kept on the mid-span of the bridge.
3. After that weight will be increased in 1 kg intervals and the ultimate load carrying capacity (Fu) of the bridge will be evaluated at the point of failure.

Definition of Failure

The bridge is considered failed when:
a. The vertical deflection at the mid span exceeds 50mm
b. Any member or joint fails.
c. At any point of time, the structure, other than towers, touches the platform.

Judging

1. Ultimate Load Carrying Capacity (Fu)
   35 points will be awarded to the team with largest ultimate load capacity, and the remaining teams would be awarded points based on linear interpolation of their own capacity between the maximum(largest ultimate load capacity) and the minimum(15 kg as per rules). Note that the entries carrying a weight less than 15kg’s will be awarded zero.
   
2. Predicted Ultimate Load Carrying Capacity (Fp)
   The error in prediction of the ultimate load carrying capacity will be calculated by the following equation:
   e=|Fp-Fu|/Fu
   where
   Fp=Predicted ultimate load (kgf)
   Fu=Ultimate load attained in competition (kgf)
   15 points will be awarded to the team with the lowest error, and zero point to the team with the highest error, and all others will be awarded points based on linear interpolation between these two extremes.
   
3. Structural Efficiency (E)
   The structural efficiency will be calculated by the following equation:
   E=Fu/m
   where
   Fu= Ultimate load attained in competition (kgf)
   m= Dead weight of bridge as measured at the competition
   50 points will be awarded to the team with the highest score in this category, and all others will be awarded points based on their structural efficiency as a fraction of the highest score. Less than 10 kgf load supported means zero points.
   

General Rules

1. Shape: Structure could be of absolutely any shape satisfying the above constraints
2. If any of these constraints are not met, point deductions (as mentioned) or disqualification may be imposed at the sole discretion of the Organisers.
3. Once the structure is weighed, you are not allowed to modify your structure in any way
4. If the structure fails to satisfy any of the above constraints then it will be summarily rejected
5. Any team that is not ready at the time specified will be disqualified immediately
6. Judges' decision shall be final and binding on all
7. The organisers reserve all rights to change any or all of the above rules as they deem fit. Change in rules, if any will be highlighted on the website.

Team Specifications

A team may consist of a maximum of 4 members. Students from different educational institutes can form a team.

Eligibility

All students with a valid identity card of their respective educational institutes are eligible to participate in Canyon Cross at Techfest 2011.

Compliance

At check-in, event Organisers will evaluate each bridge. Bridges will be weighed, measured, and reviewed for compliance with rules regarding materials.
If a bridge does not comply with any of the rules,

1. Bridges that are completed but do not meet the construction guidelines will be given a chance to make any necessary alterations.
2. No alterations will be allowed unless deemed necessary by the Judges. If such alterations are required, the team will be allowed thirty (30) minutes to complete them. The decisions of the Organisers are final.

Accommodation

1. Due to the limited accommodation facilities, teams will be short listed for accommodation based on the following abstract provided by the team. Please note that even if your abstract does not get short listed, you are still eligible to participate in the competition.
2. All participants who want accommodation at IIT Bombay during Techfest should fill the abstract form and rename the .doc file as "TeamID.doc"(example: CY1001.doc) and email the form to canyoncross[at]techfest[dot]org with the subject of the mail as “CanyonCross_Abstract”. The abstract should reach us latest by 2359 hrs on 1st December 2011. No more requests for accommodation will be entertained thereafter.
3. Click here for the abstract format

Accommodation Criteria

1. Teams have to summit a description of their model, supported by blue print of the model.
2. The typed abstract should not exceed two A4 sheets of text with Times New Roman font size of 12 excluding the first sheet containing the title.
3. Diagrams should be on additional sheets (graphic/animation representation of the project is encouraged). The abstract should be concise and to the point.
4. Once the abstract is submitted then the participants will not be able to change the machine, if they wish to change the logic of the machine they will have to re apply and submit the same.
5. Abstract should be mailed to canyoncross[at]techfest[dot]org with subject of the mail ‘Canyon Cross Abstract’.
6. Last date of submission of abstract is 1st December 2011.

Certificate Policy

1. Certificate of Excellence will be given to all the winners.
2. Certificate of Participation will be awarded to the teams who are able withstand minimum load of 15kg’s.

The following teams have been provided with the accommodation on the basis of the abstract that has been submitted. Please note that even if you are not provided with the accommodation, you are still eligible to participate in the competition. Further additions will be made to the list.

1. 2694
2. 2660
3. 2630
4. 2697
5. 2664
6. 2709
7. 2615
8. 2657
9. 1193
10. 2740
11. 2675
12. 2550
13. 2702
14. 2703
15. 2534
16. 1229
17. 2458
18. 2627