The Dos Hermanos Bridge project in Puerto Rico reconstructed a structurally deficient bridge, addressing environmental, historical, and cultural considerations in addition to traditional transportation needs. The project, completed in 2011, includes the demolition of the old bridge and the construction of a new four-lane, arched-beam bridge with sidewalks, a bike lane, traffic monitoring cameras, and lighting.
The previous structure of the Dos Hermanos Bridge was in an area with sensitive sea grasses and historic and archaeological resources. These sea grasses are part of the essential fish habitat and are particularly important for sea urchins. The bridge replacement project included a sea grass mitigation plan, which required the transplant of the sea grasses to an area of the lagoon outside the direct impact area, where there was good light penetration, protection from strong wave action, and an adjacent distribution of three sea grass species. The mitigation effort also included biannual monitoring of the area's sea grass species to track and support their survival. After the permitting process concluded, isolated coral colonies were identified and found to be attached to the bridge pilings. The Dos Hermanos project team then led minimization and mitigation efforts to preserve these coral colonies.
An important aspect of the Dos Hermanos Bridge project was the protection of historic and archaeological resources. The project included an archaeological treatment plan, which required the use of particular construction sequencing steps and methods and restricted the project's construction footprint. No explosives were used for the demolition, and low impact equipment was required. Debris and dust removal were also addressed as part of the archaeological treatment plan, and seismic monitoring was conducted to ensure that vibrations from construction efforts did not damage these fragile resources.
The Dos Hermanos Bridge project was a collaborative effort to address safety and travel needs in an area known for its tourist attractions, sensitive environmental habitat, and fragile historical and archaeological sites. The Dos Hermanos Bridge project serves as a strong example of how transportation infrastructure projects can protect the environment, preserve cultural heritage, and provide safe access for drivers, bicyclists, and pedestrians.
For more information, contact Cathy Kendall, Federal Highway Administration, Puerto Rico Division, at Cathy.Kendall@dot.gov.