Scoring and Rules

The steel bridge competition has many rules which make it challenging.

Each member of the bridge must meet the following criteria:

• less than 3 feet long
• less than 4 inches wide
• less than 6 inches deep
• cannot be internally threaded
• consist of steel that is magnetic (this eliminates stainless steel)

For the timed build, a simulated construction environment is used with two staging yards, two transportation zones, a construction zone and a "river". There is one staging yard and one transportation zone on each side of the river and the construction zone is on both sides of the river.

The timed build begins with every member, nut, bolt, and tool on the ground in one of the staging yards. When the clock starts, the build team collects their tools, nuts, and bolts to begin construction of the bridge. Each person on the build team can only carry one member of the bridge across the transportation zone to the construction zone where it joins a constructed portion. Once the build is complete, the build team must return to the staging yard to stop the clock.

Penalties:

• dropping a tool, nut, bolt, or member results in 15 seconds being added to the overall build time
• if a person on the build team touches the river, the score is calculated as if there was an additional builder

Scoring:

• The construction cost is estimated as $70,000 per person-minute

Once constructed the bridge is inspected by judges for improper construction. The bridge is also weighed.

Penalties:

• if a bolt or nut is not completely tight, 25 pounds is added to the overall weight of the bridge

Scoring:

• If the bridge weighs less than 120 pounds, the cost is $5,000 per pound for penalties
• If the bridge weighs more than 120 pounds and less than 200 pounds, the cost is $5,000 per pound for penalties and any weight over 120 pounds
• If the bridge weighs more than 200 pounds, the cost is $25,000 per pound for penalties and any weight over 184 pounds

The bridge is subjected to a 50 pound lateral load while the sway is measured.

Penalties:

• If the sway exceeds 1 inch, the bridge fails testing

Scoring:

• This test is pass or fail

The bridge is loaded with 2500 pounds and the deflection is measured.

Penalties:

• If the deflection exceeds 3 inches, the bridge fails testing

Scoring:

• deflection is valued at $3,000,000 per inch of deflection

The construction economy (cost of timed build) and the structural efficiency (cost of deflection and weight) are added together to get the total construction cost of the bridge. The winner is the bridge with the lowest cost.