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Bascule Bridge

NOTE: MANUAL ACTUATION FOR OC Mechanism is allowed. However, direct MANUAL pulling of strings to lift up the DECK is not allowed.
Registrations for Bascule Bridge are Closed.
Results for Accommodation Declared. Click here.

basculebridge_techfest

"Strive for perfection in everything you do. Take the best that exists and make it better. When it does not exist, design it." - Sir Henry Royce

First used in the early years of the 19th century, bascule bridges have come a long way in shaping modern transportation. Be it the London Bridge or the Mystic River bascule bridge, these beauties are the pride of every city that uses them and building one is an engineering marvel in itself. Techfest 2010 gives you a chance to own your very own suspension bridge with nothing but Popsicle sticks.

1.1 Problem Statement

Design and build a Bridge using Pop-sickle Sticks that allows a block of dimension 300mm(breadth) * 300mm(height) * 400mm(length) to pass between the towers of the bridge across the deck when the leaves of the deck are opened and also allows the given load to pass over the deck with minimum deflection of deck in the closed position.

Register here for Bascule Bridge. Prizes worth INR 16,000 to be won.

For answers to your queries/doubts, visit our Forum.

View the Bridge and Plot Specifications »


For further queries contact:

Harshad Patil
Manager, Events
Techfest (2009-10)
+91 99307 48038
harshad[at]techfest[dot]org

Nishank Gupta
Manager, Events
Techfest (2009-10)
+91 98204 51800
nishank[at]techfest[dot]org

2.1 Bridge Specifications

Construction of a bascule bridge involves sequential construction of four components i.e. towers, anchorages, deck structure, OC mechanism (Opening and closing mechanism of the deck).

2.1.1 Anchorages:

Anchorages will be provided by the organizers. They will be C-shape channel sections 200 mm high and the distance between these C-shaped channels will be 1000 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 organizers.

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Anchorage

2.1.2 Towers:

  1. The tower of the bridge should not have a base area greater that 80mm * 80mm. The depth of the groove for the tower to rest is 50mm.
  2. The distance between the two towers (measured centre to centre)should be 700 mm(Refer Figure).
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Top View of Tower Base

2.1.3 Deck Structure:

  1. The height of highest point of deck's top should not be greater than 210 mm and should not be lesser than 190 mm from the platform.
  2. When the bridge is opened, the length of the movable leaves of the deck, should not be greater than 380mm
  3. A loaded trolley will be moved along the deck of the bridge. The width of deck at any length should be 170mm
  4. The hinges should be free about its axis to rotate and the hinges should not support the movable leaves by locking mechanism at any point of time. The leaves can take support from the towers and from the strings. Uses of readymade hinges are not allowed (example: the hinge of door). Materials other than popsicle sticks and strings are strictly prohibited and cannot be used for the preparation of a hinge
  5. In case of the use of cable to support the deck or tower, the strings should be made up of single layer string only. Multiple layered strings or multiloops are not allowed
  6. Strings can either be glued to the deck or you can knot the string to the popsicle sticks
  7. Maximum number of cables used between the two towers can be 8, i.e. 4 on each side of the bridge
  8. 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
  9. OC mechanism can be either electrical or mechanical. Any other mechanism should be conveyed to the organizers prior to the event by sending a mail with topic "Bascule Bridge: BR. The OC Mechanism" to basculebridge@techfest.org
  10. The assembly used for the OC mechanism should not be in contact with the hinges at any moment in any way
  11. In the electrical mechanism, the assembly of the mechanism should be kept on the platform and should be connected to the bridge only through strings. See figure
  12. Use of any other material for the OC mechanism, other than Popsicle sticks and thread is not allowed
  13. If an electrical motor is used by the participant then the power source of the motor will be brought by the respective participant
  14. Once the leaves are lifted to its maximum extend, it should remain stable in the opened position without the external/ manual support at any part of the bridge. The bridge should remain stable without any interference either in the OC Mechanism or directly on the bridge

2.1.4 Plot Specifications:

  1. Two wooden channel sections will be provided as shown in the figure. The centre of the wooden section will be 1000 mm apart.
  2. A total of 4 clamps (2 on both the section) will be fixed at both of the section. Your extended deck will be supported by this clamp.
  3. The pillar structure will be mounted on the 2 zones shown in red. Each zone is 80 mmx80 mm with a depth of 50 mm. Distance between the centers of the two zones is 700 mm. They are placed 150 mm respectively from each channel section.
    The board will be provided by the organizers.
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Top View Side View
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Setup 1.
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Setup 2.

2.1.5 Trolley:

The following are the dimensions of the trolley which carries the weight.

  1. Trolley Length: Less than 180 mm
  2. Trolley Width: Less than 140 mm
  3. Wheel to Wheel width interior(axle length): 82 mm tolerance 10%
  4. Wheel thickness: Less than 10 mm
  5. Trolley Height: Less than 150 mm

2.1.6 Materials:

  1. Glue: Adhesives (Synthetic white adhesive or single component cyano-acrylate adhesive) can only be used to build the structure. (Adhesives such as M-Seal® are not allowed)
  2. Coatings: Structures may not be painted, sprayed or dipped in any coating material. All glue should be removed from surfaces that are not bonded together.
  3. Strings: Threads (cotton only, synthetic material threads will be disqualified). 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. Popsicle Sticks: Popsicle sticks (maximum length 120mm, width 15 mm and thickness 4 mm). The Popsicle sticks can be cut or trimmed to any shape or size.
  5. Hinges: Readymade hinges are not allowed. The weight of the hinges will be counted in the weight of the bridge. The hinges should be free about its axis to rotate and should not support the leaf by locking mechanism at any point of time. Materials other than Popsicle sticks and strings cannot be used for its making. The assembly of the OC mechanism is not allowed to directly rotate the hinge.

View the Testing and Judging Criteria »

3.1 Testing

3.1.1 Round 1

  1. Participants will be asked to open the deck by activating the mechanism used for it. This mechanism may be electrical or/and mechanical. Bridge should not get opened by a sudden jerk. This will be judged by the organizers and their decision will stand final. Penalty will be levied otherwise. Both the leaves of the deck should not take more than 90 seconds to get opened to its maximum capacity. If failed then the points of this round will not be added to that team's total score
  2. The box of dimension 300*300*400mm3(b*h*l) will be passed along the channel marked in the centre of the platform as shown in figure 2. While passing, no part of the bridge should touch the box else a penalty will be levied. After this test the participants will be asked to close the deck by the same mechanism which was used to open it. Deck should not be touched at any point of time during this operation. If box is not able to pass the channel, as judged by the organizer, then points of this round would not be added to that team's score. The team will proceed for the next round

3.1.2 Round 2

  1. A platform of rubber will be laid over the deck starting from one anchorage and extending to the other one
  2. A trolley with a load in it (Total weight of the load and trolley will be 15 Kg) will be moved on to the deck from one tower to the other
  3. The trolley will be fabricated and provided by the organizers
  4. The participant will be required to pull this trolley on the full length of the bridge. A string will be attached to the trolley for the same purpose and can be pulled by the application of a force which must lie in a plane parallel to the bridge surface at every point of its movement.
  5. Testing of the structure will involve the measurement of deflection of the deck when the centre of loaded trolley reaches the centre of the deck as marked by the participant on the deck and checked by the organizer. A mark on the trolley will denote the centre of the trolley. In case of a failure of the structure the points for this judgement will not be added to the respective team's total score
  6. Other way of the testing the structure will involve the total weight of the bridge which includes the weight of the structure excluding the weight of the assembly used for the OC mechanism
  7. However a participating team reaching till the completion of this stage will still be eligible to compete on the basis of its score till then.

3.1.3 Round 3

  1. The participants will be asked to repeat the steps as in Round 1 All 3 rounds will occur in succession and no time and chance will be given to the participants for the repairing work once the series of rounds has started

3.1.4 Definition of Failure

  1. Structure fails to satisfy any of the constraints specified above.
  2. Structure breaks at any joint or is not in a condition to carry the load over it.
  3. At any point of time structure, other than towers, should not touch the platform.

3.2 Judging Criteria

3.2.5 Scoring and Penalties for Round 1:

  1. A team clearing all the criteria of first round can gain a maximum of 20 points.
  2. A penalty of jerk opening of the deck will be 10 points.
  3. A penalty of box passing across the deck by touching the structure in any way will be 5 points.
  4. A team will suffer a loss of all 20 points if its unable to satisfy all the criteria laid for this round as in the bridge specifications and testing of Round 1.

3.2.6 Scoring and penalties for Round 2:

  1. A best team clearing all the criteria of second round can gain a maximum of 70 points. The best team will be decided on the basis the scoring described below.

Scoring on Weight of the Structure

  1. The scoring for this will be done by the following formula
  2. Your Score = (Weight of the lightest structure in the competition/ Weight of your structure) * 42.

Scoring on Deflection of the Structure

  1. The scoring for this will be done by the following formula
  2. Your Score = (Minimum deflection for any structure in the competition/Deflection of your structure) * 28 .
  3. In case of a failure the deflection will be counted as infinity and the score on the deflection of the structure will be zero (0).

If the failure occurs in course of this round the participant will not be eligible for the third round. But, however they will be still eligible to compete with the any other team on the basis of the points they score till then.

3.2.6 Scoring and penalties for Round 3:

  1. A team clearing all the criteria of third round can gain a maximum of 10 points.
  2. A penalty of jerk opening of the deck will be 5 points.
  3. A penalty of box passing across the deck by touching the structure in any way will be 2.5 points.
  4. A team will suffer a loss of all 10 points if its unable to satisfy all the criteria laid for this round as in the bridge specifications and testing of Round 3.

View the Rules »

4.1 General Rules

  1. Shape: Structure could be of absolutely any shape satisfying the above constraints
  2. Once the structure is weighed, you are not allowed to modify your structure in any way
  3. If the structure fails to satisfy any of the above constraints then it will be summarily rejected
  4. Any team that is not ready at the time specified will be disqualified immediately
  5. Judges' decision shall be final and binding on all
  6. The organizers 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.

4.2 Team Specifications

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

4.3 Eligibility

All students with a valid identity card of their respective educational institutes are eligible to participate in Bascule Bridge at Techfest 2010.

4.4 Compliance

At check-in, event Organizers 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 fifteen (15) minutes to complete them. The decisions of the Organizers are final.

4.5 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 ".doc" and email the form to basculebridge[at]techfest[dot]org. The abstract should reach us latest by 2359 hrs on 15th December 2009. No more requests for accommodation will be entertained thereafter.

  3. Click herefor the abstract format

4.5 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 basculebridge[at]techfest[dot]org.
  6. Last date of submission of abstract is 15th December 2009.

4.6 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 to clear the first two rounds without failure of structure and also are able to score morethan or equal to 40 points in all the three rounds.

4.7 Important Dates

  1. 15th December 2009: Last date to submit abstract to get accommodation at IIT Bombay during Techfest 2010.
  2. 5th December 2009: Last date for submission of online accommodation form for participants who require accommodation at IIT Bombay during Techfest 2010.
  3. 5th January 2010: Last date of registration for participants who do not require accommodation during Techfest 2010.

Register here for Bascule Bridge

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