(The following story by William Ryberg appeared on the Des Moines Register website on August 13.)
DES MOINES, Iowa — A four-person company in northeast Iowa has developed a tool that could have a future in helping to assure bridge safety.
Even before the collapse of the interstate bridge in Minneapolis, Reference LLC in Elkader had developed a tiny, affordable instrument for measuring bridge movement.
“Everybody has wanted to advance the art of bridge inspection, even before the tragedy,” said Christopher Kavars, chief executive of Reference.
Reference’s contribution to the cause is a cell-phone-sized machine that the company makes and markets under the brand name Sensr.
The device measures and records an object’s tilt, orientation and motion – movement from side-to-side or up and down, for example. It also can detect when an object is subjected to impact.
Sensr is designed for a variety of uses.
The instruments, for example, can be used for monitoring the shipment of fragile objects or equipment, providing a record that shows whether they were handled too roughly. It can show if cargo was handled inappropriately, such as being tipped on their side when it was supposed to always remain upright.
NASA has used Sensrs to monitor the shipment of aircraft models being used for testing, Kavars said.
Kavars also says the battery-operated device can be used to monitor the movement of bridge piers and other parts of bridge support systems.
Applications so far have involved railroad bridges, but the units could be used on highway bridges as well, Kavars said.
The BNSF Railway Co. has been experimenting with Sensrs on a few bridges, including one in Burlington, for the past few months, said Don Lozano, the railroad’s assistant director of structural design in Kansas City.
He is pleased with the results so far. The unit is “rugged, affordable and accurate,” said Lozano.
Sensr isn’t a stand-alone inspection, but can provide important data that can be used along with other bridge inspection and monitoring tools, Lozano said.
Work with Sensr instruments at the BNSF Railway involves establishing a baseline of bridge pier movement for a bridge that is in good condition, said Lozano. Once a baseline is established, increases in movement in the future would be an indication to inspectors that there could be a problem with the bridge, he added. Structural engineers could then do other testing to determine the cause.
Bridge safety is important to the railroad, which has nearly 14,000 bridges in 28 states and two Canadian provinces. The Sensr could be a “first line of defense” in detecting problems, Lozano said.
Terry Wipf, director of the bridge engineering center at Iowa State University, said monitoring the structural health of bridges involves a combination of methods, machines and technologies.
Visual inspection can find concerns that can be investigated further with ultrasound readings or X-rays, Wipf said.
Improvements in assuring structural soundness are constantly being sought, and instruments like Sensr can be part of systems that monitor bridge health, said Wipf.
Sensr isn’t unique in what it does – it is a type of motion-recording instrument known as an accelerometer.
A main selling point for the Sensr is price, Kavars said. Sensr’s price is $599, while many machines that do similar measurements cost between $2,000 and $4,000, he said.
Reference is also working on plans to create an improved tool for measuring bridge motion and other factors.
The Minneapolis accident has created heightened awareness about bridge safety that could lead to a race among companies to create a more comprehensive bridge monitoring instrument, Kavars said.
However, the recent accident hasn’t led to a rush of new business for Reference, possibly because the firm isn’t widely known, he said.
Reference has been in contact with the Wisconsin Department of Transportation and the Federal Highway Administration to try to interest the agencies in the Sensr instruments.
Reference also would like to make a pitch for the product to the Iowa Department of Transportation, Kavars said.
Ahmad Abu-Hawash, chief structural engineer for the Iowa DOT, said the agency is always looking for new methods and instruments to improve bridge safety monitoring.
“We have quite a few research projects where we use different sensors, such as strain gauges and accelerometers,” he said.
Kavars, 41, and two partners, Leslie Davis and Ron Green, founded Reference in 2003.
All three had worked together off and on over the years in product development at other companies. They decided to strike out on their own.
Reference specializes in the design, manufacture and sales of dynamic recorders, instruments that measure motion.
Reference hires other companies to make some components, but assembly work is done in Elkader.