Students to Test Physics Laws by Destroying Bridges at Southern Nevada Model Bridge Contest at UNLV

Media Contact: Steve Leon, 702-293-8456
Paul Matuska, 702-293-8164

For Release: February 26, 2009

On Saturday, February 28, hundreds of students from more than 50 local elementary, junior, and senior high schools will test their math, physics and budding engineering skills at the 20th Annual Southern Nevada Regional Student Model Bridge Building Contest.

The students will showcase their skills, ingenuity, attention to detail and weeks of planning, designing, and building wooden model bridges that weigh less than one ounce, and then submit the the bridges for testing and enthusiastically watch as their bridges are destroyed in seconds.

This exciting and educational activity will be held at the Engineering College of the University of Nevada-Las Vegas (UNLV).

"The objective of the contest is to test the load-bearing capacity of each individual's bridge and teams bridge by compressing it to the point of failure," said Paul Matuska, Bureau of Reclamation engineer and long-time Bridge Building event planning committee chairperson. "Or stated another way, we press on the bridge with a materials testing machine that uses increasing pressure to simulate weight until the bridge finally breaks.

"The bridges are then ranked according to efficiency, calculated by dividing the total weight the bridge supports before failing by the weight of the bridge," he said. "This type of machine is also used to determine the tensile strength of a material. That is, to determine the minimum amount of longitudinal stress needed to pull the material apart."

Contest specifications require all entries in the model bridge building contest to be designed and constructed according to strict standards. The students can use only the 3/32-inch-square cross-section basswood included in the kits supplied to the schools by the sponsors. The wood may be notched, cut or laminated in any manner, and fastened with any commonly available glue. But no other materials may be used in the bridges construction.

Other restrictions are that the bridge mass/weight must not exceed 25 grams (just under one ounce); the finished bridge must span a distance of 300 millimeters (about 12.5 inches); the maximum length cannot exceed 400 mm (about 16.5 inches); the maximum height is 120 mm (about 5 inches); and the maximum width must be 80 mm (about 3 inches).

In past competitions, bridges designed to these specifications have been tested to pressures equivalent to support weights as high as 350 pounds.

In addition to Reclamation, the contest is sponsored by the American Society of Civil Engineers in coordination with UNLV and the Clark County School District, the Clark County Public Works Department, Poggemeyer Design Group, Terracon Engineering and other local engineering firms.

# # #

Reclamation is the largest wholesale water supplier and the second largest producer of hydroelectric power in the United States, with operations and facilities in the 17 Western States. Its facilities also provide substantial flood control, recreation, and fish and wildlife benefits. Visit our website at and follow us on Twitter @USBR.