Competition Overview

In this competition, teams will design and build a bridge using basswood. The event is intended to test a range of skills, including technical design, efficiency, cost management, accuracy of predictions, and the ability to work within time and size constraints.

Each team will be given a budget of $1500 GSTC to “purchase” materials for their bridge design. This introduces an additional layer of strategy, as teams must balance structural performance with material cost and efficiency.

At the end of the competition, bridges will be load tested until failure to determine their maximum load capacity. This value makes up a significant portion of the total score.

Construction Phase

The construction phase runs from 2:30 PM to 5:30 PM and is divided into two parts:

• Design Phase: Used for planning and selecting materials from the marketplace. Teams have 20 minutes before “while building” pricing takes effect.
• Building Phase: Teams construct their bridge using only purchased materials. No external references or pre-made templates are permitted.

Once materials are purchased, they are considered final and may not be refunded or exchanged (except for defective materials approved by judges).

Testing Process

Teams will be called up in random order for testing. Each test takes approximately 3-7 minutes per bridge.

• Loading is conducted using a bucket and sand system (or equivalent incremental method)
• Sand is added in equal increments until failure occurs
• Failure = 2″ maximum vertical deflection OR any structural member/joint fails
• Testing terminates when load reaches 200 lbs, regardless of bridge failure status
• Bridges that cannot accommodate the loading apparatus receive a modified setup but incur a 15% penalty

Submission Worksheet

Each team receives a worksheet to complete during the competition. It must be filled out before the end of the building phase:

• Estimated maximum load
• Predicted failure mode
• Short description of your bridge (optional, may be considered for aesthetics scoring)

After submission, teams may leave for dinner while judges evaluate bridges, record remaining budget, and complete scoring. No modifications may be made after the building period ends.

Overall Dimensions

All dimensions measured at the widest, tallest, and longest points of the bridge. No maximum weight is specified.

Loading Specifications

• Load applied at the center of the bridge span (midpoint of the roadway)
• Loading system: rigid 3″ x 3″ x 1/2″ loading plate attached to a central hook
• Minimum 1.5″ x 1.5″ clear vertical clearance directly below the loading point
• Plate must be fully supported by the bridge — may not rest on voids or openings

Roadway & Clearance

A 3″ x 3″ x 3″ clearance cube must be able to pass through the full length of the bridge without obstruction. A continuous roadway deck is not required, but the center of the span must provide a stable load-bearing surface.

Laminated Members

• Members may be built up by laminating multiple basswood strips together
• Each laminated member may contain up to 6 strips total in its cross-section
• May not exceed 4 layers in height or 4 layers in width
• Parallel laminated members must be spaced at least 1/4″ apart
• Must maintain truss-like or beam-like geometry — no solid slab-like blocks

Supports

The bridge must rest only on the provided supports at each end. No abutments, anchors, or additional support structures may be used. The contact must be purely vertical — the bridge may not exert horizontal forces on the supports beyond friction.

Material Regulations

Allowed: Cut/notched to any angle, sanded, bent using water only, marked with pencils/pens, decorated with colored pencils/markers.

Not Allowed: Soaked/coated/treated with anything other than water, impregnated/reinforced/hardened using adhesives or external substances beyond normal joint bonding.

Materials Marketplace

Each team receives $1500 GSTC (Garden State Truss Currency) to purchase materials. The currency used is not real money. All listed materials are optional to purchase and use in the construction of the bridge.

The “While Building” cost is approximately 130% of the “Before Building” cost, reflecting the increased expense of in-competition purchasing. There is also up to a 15% bulk discount on basswood strips, allowing teams to purchase 30 strips (instead of 10) at a cheaper per-strip price. However, teams must determine if they are willing to commit to buying in bulk and are encouraged to plan ahead.

Teams will have exactly 20 minutes to make purchasing decisions before the while-building pricing takes effect. If a team has not placed any material orders after 20 minutes, the pricing will automatically switch to during-building pricing regardless of design progress.

Basswood Strips, Sheets, Adhesive & String

All structural materials available for purchase. Prices are listed in GSTC. 30-strip options offer a bulk discount compared to the 10-strip equivalents.

Purchasable Tools

Tools used during construction must not be part of the final bridge. All listed tools are optional to purchase and use to assist in bridge construction.

Free Tools & Materials (Provided)

The following tools and materials will be provided to all teams free of charge for use during construction. Items marked with an asterisk (*) are available upon request and may require approval/supervision from judges, as they are not commonly used or may have restricted usage depending on the situation.

Budgeting & Purchase Rules

• Teams may purchase materials at any point during the competition from the designated marketplace.
• Money may not be transferred or shared between competing teams.
• No refunds will be issued. However, if a material is defective (e.g., a broken basswood stick or faulty glue), it may be exchanged for a replacement.
• Any unused budget remaining at the end of the competition will contribute to the team’s final score, so teams are encouraged to not spend their full budget.
• Teams are responsible for managing their own GSTC funds. Any lost or mismanaged funds will not be replaced by the organizers.
• Theft, attempted theft, or interference with another team’s funds is strictly prohibited and will result in disqualification.

Material Regulations

Basswood strips may be physically altered in the following ways:

• Cut or notched to any angle or length
• Sanded to adjust width or surface smoothness
• Bent or curved using water only
• Marked on the surface using pencils, pens, markers, or similar tools for measurement or labeling purposes
• Decorated with colored pencils or markers

The sticks must NOT be altered in the following ways:

• Soaked, coated, or treated with any substance other than water
• Impregnated, reinforced, or hardened using adhesives or any external substances beyond normal joint bonding

The Bank

At any point during the competition, teams may exchange larger bills for smaller ones or combine smaller bills into larger ones. This is the only function of the competition bank. The bank does not provide any additional services, such as loans, investments, interest, or taxes. It is strictly used for changing bill denominations.

For example, a team may exchange one $100 GSTC bill for five $20 GSTC bills if needed to purchase smaller items at the Materials Marketplace.