Engineers at the University of Maine Composites Center have introduced an innovative new bridge system that can be built in just 72 hours and last 100 years with only minor routine maintenance and repairs.
The system was recently unveiled in a strength test attended by Maine Department of Transportation officials, local business leaders, investors and researchers. In a laboratory setting, UMaine engineers proved their design is capable of standing up to the rigors a highway bridge span would be expected to endure, using computer-controlled hydraulic equipment to simulate heavy highway vehicle loads.
“Today’s bridge test exceeded our expectations. The composite bridge withstood forces equivalent to more than 80 cars stacked on top of each other…The composite bridge girder exceeded twice the collapse strength of steel and concrete girders…,” Dr. Habib Dagher, executive director of UMaine’s Advanced Structures and Composites Center said in a university news release.
The university says the resulting lightweight highway bridge superstructure can be completed in just 72 hours.
The secret to its rapid deployment is UMaine’s patent-pending system, which uses composite girders weighing just 1 to 2 tons for 40 to 80-foot spans that can be placed using widely available local equipment. The span itself is formed from precast concrete deck panels, which saves time and simplifies logistics during construction. The university says the resulting lightweight highway bridge superstructure can be completed in just 72 hours, and can be used for highway, pedestrian or military applications, engineers told Construction Dive.
The lightweight design and relative ease of construction doesn’t mean there’s been any kind of compromise on strength, however. The girders are designed to last 100 years, according to UMaine, and the precast concrete deck can be easily replaced or removed as needed. UMaine says the system is meant for short- to medium-span bridges, up to 80 feet for unsupported spans.
UMaine’s bridge system was designed with logistics and portability in mind. Since the composite materials used are much lighter than typical bridge girders, and because the pieces were engineered to nest together, a single flatbed truck can transport up to four complete bridges at a time. Once the pieces arrive on site, the girders can be installed using standard equipment as opposed to specialized cranes strong enough to lift the tremendous loads customarily associated with bridge building.
This isn’t UMaine’s first go-round designing innovative bridge engineering methods. Nearly a decade ago Dagher’s team began developing its now-patented Composite Arch Bridge System, known as Bridge-In-A-Backpack because of its lightweight, easily transportable materials, and because of its ability to be installed without heavy machinery or a big crew. The system, licensed by the university to startup Advanced Infrastructure Technologies, is now deployed at 23 spans all over New England, Michigan and Pennsylvania, even in Trinidad and Tobago.
The university will next test the bridge system to the point of structural failure so it can determine its collapse rate.
Advanced Infrastructure Technologies has also licensed UMaine’s new system, and is eager to start deploying it. Brit Svoboda, AIT Bridges Chairman and CEO said in a university news release, “we’re ready to go to market.”
There is still more testing to be done before that can happen. The university will next test the bridge system to the point of structural failure so it can determine its collapse rate.
The bridge system test garnered UMaine attention and praise from the state’s elected officials.
“Maine, New England, and our nation need innovative technologies that will accelerate bridge construction, reduce traffic disruptions, increase the lifespan of infrastructure, and decrease costs to the taxpayer. The private sector partners and DOT officials attending the test will help to ensure that such critical technologies are quickly brought to market. As longtime supporters of UMaine R&D, we applaud the University for its continued leadership in transportation and infrastructure innovation,” U.S. Sens. Susan Collins and Angus King wrote in a joint statement.