Unlike the famed launch site of the space shuttle, this muddy corner of South Salt Lake sported a small BYU "rocket." The goal of the rocket device - designed to reach an altitude of about 15 feet - was to create a brief, simulated earthquake.

The launch pad rested on top of a foundation that will one day support a state Route 201 overpass. This low-altitude mission tested the foundation's piling, said BYU's lead researcher Kyle Rollins.

The blast - which unleashed 900,000 pounds of force in 1/10th of a second - will help engineers learn how to design cheaper, sturdier bridges.

"We want to have the bridge safe, but everyone is tight on money and budgets are always getting cut, so we'd like to be able to do that as efficiently as possible," Rollins said.

A major way to cut costs in bridge construction would be to use fewer pilings in the foundation. The pilings, driven into the ground, extend up into an abutment, which is a concrete block. Girders, which sit on the abutment, support the bridge deck.

Rollins said that some engineers suspect that current standards use more pilings than are necessary. But for engineers, hunches are not enough to make wholesale changes to how overpasses are designed.

"We don't want to go out on a limb when public safety's concerned," he said.

Results from Thursday and Friday's tests will not change how SR201's bridges over Redwood Road will be built, but they could affect the plans for future bridges.

Part of Rollins' research examines how bridge foundations might perform in earthquakes. The force of this quake would be equivalent to magnitude 7.5. However, it would only be one cycle of movement in such an earthquake, which consist of multiple cycles.

Along with scientists from the University of Idaho and the University of South Florida, Rollins installed sensors in the piling and in the ground surrounding the foundation.

"We can measure how much stress it's under," said BYU grad student Brian Sears of the piling.

Equally important in this work is what happens to the soil. Plenty of research has been done about sand in an earthquake. Little is known about how clay soils, such as those found in the Salt Lake Valley, react. This test could help Salt Lake City and its sister clay-soiled cities, like San Francisco and Seattle.

The main concern is known as liquefaction. Shaking can cause soils to liquefy and lose their strength.

"It can become like quicksand," Rollins said. "Buildings sitting in it can sink into the ground."

Earthquake conditions are not the only benefit to this test. Traditionally, when testing resistance in pilings, builders will heap tons of weight onto a foundation and leave it for 24 hours, he said. The experimental system, which is based on technology developed over the past six years, takes 1/10th of a second.

At the heart of the system is a skinny, yellow rocketlike apparatus. A crane eased the payload - blue, steel boxes filled with tons of rock - down onto the rocket's shaft. The rocket sits in an open steel frame until its launches, when hydraulic arms catch it in midair to prevent it from crashing to the ground.

Rollins said about three boxes of varying sizes carried a combined load of about 40 tons.

A construction worker on Thursday afternoon handled a hose, leading from a nearby truck, that poured water into the boxes. Sears said the water adds more weight for the test.

Hundreds of finger-sized explosives, known as fuel pellets, were loaded into the rocket. Around 6:30 p.m., a spark set off an explosion that sent the square projectile airborne. The launch occurred a few hours late, as researchers made an emergency run to Radio Shack for some last-minute parts.

The explosion pushed the rocket into the air, while at the same time unleashing the same amount of force against the piling being tested.

On Friday, the equipment moved a few hundred feet south to test pilings for the second bridge that will hold Route 201. After that, the launch pad will be moved into storage.

Rollins hopes that the test will prove the procedure's worth and that similar equipment will one day become standard fare for bridge builders.

glavine@sltrib.com