• ToothPick Engineering
    Toothpick Engineer
    How to build a toothpick bridge:http://toothpickengineer.com/
    ToothPick Engineering is Dentists Hobby from Popular Science 1940:
    Toothpick Bridge Competition: http://web.mnstate.edu/bridge/Index.htm
    West Point Bridge Design

    The Challenge:

    The competition is open to all students grades 1 through college. Students are invited to build a structure using only round wooden toothpicks and glue that:

    • Spans more than 56 centimeters.
    • Stands no more than 30 cm tall.
    • Weighs less than 85 grams.

    You'll load your bridge with weights as shown. When the bridge breaks, we divide the load it held by the weight of the bridge to determine its strength. The strongest bridges win cash prizes!

    (Note: In the interest of contestant safety, the competition sponsors are expolring alternate means to apply the load - some mechanical or hydraulic device may replace the weights, but the contestants will still apply the load to their own bridges!)


     Official Rules

    Sponsored by the Fargo-Moorhead Engineers Club and

    Minnesota State University Moorhead

    The goal of the competition is to design the strongest possible structure to span at least 560 mm using only round wooden toothpicks and glue. The strength of the structure will be determined by dividing the load it supports by its weight.


    The contest is open to any student, grades 1 through 12, plus students enrolled full-time in college. Entrants will be assigned an entry class:

    Elementary (Grades 1-6)
    Middle School (Grades 7-9)
    High School (Grades 10-12)

    Bridges built by teams of students will be assigned the class of the student in the highest grade.

    Design Constraints:

    Mass: The total mass of the structure cannot exceed 85 grams (3.00 oz)

    Span: Each structure must span at least 560 mm clear of any supports.

    Height: The overall height of the structure may not exceed 300 mm.

    Toothpicks: Only round wooden toothpicks may be used (square toothpick with rounded ends will not be allowed). The toothpicks are to be glued together as they come from the box. No cutting, splicing, or fraying of the ends is allowed, except:

    • the tips of the toothpicks at the top of the structure may be trimmed off to enable the weights to rest flat on the top, and
    • the tips of the toothpicks at the ends of the structure may be trimmed to allow the structure to butt up flush with the supports.

    Glue: Only a white glue, such as Elmer's, or a yellow woodworking glue, such as Titebond, may be used. Structures built with other glue will be disqualified.

    Coatings: Structures may not be painted, sprayed or dipped in any coating material.


    At check-in, judges from the Fargo-Moorhead Engineer's Club 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, it will be disqualified from competing for the prizes, but may still be loaded to determine its strength. The decisions of the check-in judges are final.


    The structure will be placed in or on supports made from two 2x4's as shown in the illustration.. Structures with no arch in the bottom chord will be placed on the supports to achieve the required minimum span. No lateral or side support is allowed.


    Note: The minimum span is 560mm.


    Round metal weights, approximately 220 mm in diameter, will be placed on the top of the structure at the mid-span by the contestants until failure. A 160-mm round wooden disk will be available to place between the structure and the weights, if desired. Contestants may use cards to shim the base of the bridge level. Entrants in the elementary class may ask for assistance in loading their structures.

    In the interest of contestant safety, the sponsors are exploring alternate means to load the bridges. The means of support will not change, but the load may be applied mechanically or hydraulically.

    Scoring :

    Judges from the Fargo-Moorhead Engineers Club will record the total weight supported by the bridge. The judge will make the final decision as to whether a structure successfully supported the final weight before failure. The total weight supported will then be divided by the recorded weight of the structure to determine the strength ratio of the bridge.


    The three strongest bridges overall will be awarded First, Second and Third Place prizes.

    First Place - $125 and a certificate.
    Second Place - $100 and a certificate.
    Third Place - $75 and a certificate.

    The next strongest bridge in each entry class will be awarded a Best in Class prize.

    Best in Class - $40

    A panel of judges appointed by the Fargo-Moorhead Engineers Club will view all the bridges as they are checked in, and will award a prize, based on quality of construction, and overall appearance.

    Best Appearance - $40


    Competition: Held in February.

    Comstock Memorial Union Ballroom
    Minnesota State University Moorhead
    6th Ave. South and 14th St., Moorhead, MN

    Bring your bridges to the check-in tables. Parking is available in the lot to the west of the CMU. (Please call for parking instructions for busses.)

    Registration from 4:30-5:00 pm. Competition begins at 5:00. (If the number of entrants warrants, competition may begin upon checking in.)

    Bridge Truss Designs
    Are you able to identify these types of bridge trusses:
    Godden Structural Engineering Slide Library (Pictures and descriptions of real bridges)