New construction techniques may soon change the way bridges are built and replaced, as technological innovations have resulted in projects that can be completed in days, not months.
Bridge replacement projects can be a major headache for road officials, as there's often no easy detour for drivers. The complexity of replacing a bridge also means that it's not frequently a quick project, but a long-term inconvenience.
The New York Times reports that new "accelerated bridge construction" techniques may soon make those long delays history. The technology was recently demonstrated on the River Street Bridge in Boston, where replacing and adjusting the bridge was completed in just a few days. Previous estimates projected the bridge would be closed for months.
The secret lies in prefabrication. Engineers design the bridge ahead of time, and the bridge is built somewhere nearby. The old bridge is knocked down, then massive trailers carry the new bridge to the site. The trailers are installed with mechanized supports that can raise and lower the bridge slowly. The trailers are parked underneath where the old bridge used to be, then slowly raise the pre-constructed bridge into its new home.
The new technology was developed by Theodore Zoli, national bridge chief engineer for HNTB Corporation, who received a MacArthur "genius" grant for his work. The major benefit for state transportation departments is the fact that prefabricated sections can be installed one piece at a time. For example, the Golden Gate Bridge is currently being replaced in small segments, without having to completely close down the critical bridge.
Best of all, the innovation requires little new training or expertise to use. P. Gioioso & Sons, the main contractor on the River Street Bridge job, was able to complete the task in a weekend, using heavy machinery to knock down the old bridge Friday night and the specialized trailers to easily raise the new one by Sunday afternoon.
Contractors working in bridge construction need to have access to a wide array of equipment to get the job done. Concrete equipment, cranes and aerial work platforms may all be necessary. Fortunately, the online auction site IronPlanet offers all of these, and more, often at more affordable prices than buying new.
