In order to receive official wood and participate in this contest, a High School student must have placed first or second in a Regional Contest and be reported, by the Regional Coordinator, to Mark Toney, Sehome Science Dept, 2700 Bill MacDonald Parkway Bellingham WA, 98225 by mail, FAX:(360)-647-6863 or e-mail mtoney@bham.wednet.edu. Students may participate in person, by proxy or by mail entry.

The object of this contest is to see who can design, construct and test the most efficient bridge within the specifications. Model bridges are intended to be simplified versions of real-world bridges, which are designed to accept a load in any position and permit the load to travel across the entire bridge.

1. The bridge must be constructed only from the official 3/32-inch square cross-section basswood included in the kit and any commonly available adhesive.
2. The official basswood may be notched, cut, sanded or laminated in any manner but must still be identifiable as the original official basswood.
3. No other materials may be used. The bridge may not be stained, painted or coated in any fashion with any foreign substance.

1. The bridge mass shall be no greater than 30.00 grams.
2. The bridge (see Figure 1) must span a gap (G) of 300. mm, be no longer (L) than 400. mm, have a maximum width (W) of 80. mm, be no taller (H) than 250. mm above the support surfaces.
3. No portion of the bridge shall extend below the top of the support surfaces.
4. The loading plane (P) shall be horizontal and shall lie no more than 15. mm above the support surfaces. The bridge may extend above the loading plane.
5. The bridge must be constructed to allow for passage of a 1.5 inch by 1.5 inch by 18 inch long rectangular block vertically through both load points (the block will be centered on the loading point as shown in Figure 1) and horizontally across the load plane (one face of the block will be in contact with the load plane).

1. The load will be applied downward, from below, by means of a standard 3/8 inch rod and a steel loading plate with dimensions of 31.75 mm (1 1/4 inch) wide, 6.35 mm (1/4 inch) thick, and 100. mm long, resting on the load plane of the bridge (See Figure 2). Masses will be supported on a vertical loading rod suspended from the center of the loading plate. The rod will pass through the bridge and the center of the loading plate and will be secured with a standard hex nut.
2. The two long edges of the loading plate will be parallel to the longitudinal axis of the bridge at the time of load application.
3. The load will be applied on the longitudinal axis of the bridge with the loading plate centered 50. mm to the right or the left of the center of the 300. mm gap.

1. The competition loading location will be determined at random at the beginning of the contest, and will be the same location for all the bridges tested.
2. The loading plate will be located on the bridge at the specified loading location and the load will be applied from below, as described in section 3 above.
3. Competition loading will stop at 180. lbs (~82. kg). However, loading will continue until bridge failure.
4. Bridge failure is defined as the inability of the bridge to carry additional load, or a load deflection of 25 mm under the loading location, whichever occurs first.
5. The bridge with the highest structural efficiency, E, will be declared the winner.

1. All construction and material requirements will be checked prior to testing by the judges. Bridges that fail to meet these specifications at the conclusion of the allowable time for checking will be disqualified. Bridges disqualified prior to the start of the contest may be tested as exhibition bridges at the discretion of the builder and the contest directors.
2. If, during testing, a condition becomes apparent (i.e., use of ineligible materials, inability to support the loading plate, bridge optimized for a single loading point, etc.) which is a violation of the rules or prevents testing as described above in Section 4, that bridge shall be disqualified. If the disqualified bridge can accommodate loading, it may still be tested as an exhibition bridge as stated above.
3. Decisions of the judges are final; these rules may be revised as experience shows the need. (Please check our web site, http://www.iit.edu/~hsbridge, after January 15, 2009, to learn whether any changes have been made.)