When officials secured funding for the long-awaited Cross Street Bridge in Middlebury, Vermont, they wanted to move the project from concept to completion quickly. An aggressive design-build project delivery method, combined with the use of Lafarge Type III cement to maximize productivity and accelerate production, helped open the bridge in just 18 months.
The Cross Street Bridge provides a vital second crossing over Otter Creek to alleviate traffic congestion and connect residents and visitors to the city’s downtown shopping district. The $16 million two-lane bridge is the first major design-build transportation project in Vermont, and the longest simple-span precast, post-tensioned, spliced-concrete-girder bridge in the United States. It has won two PCI Design Awards, sponsored by the Precast/Prestressed Concrete Institute, in recognition of its design and construction excellence.
To maximize cost-effectiveness of the process, and meet the aggressive timeline of the design-build process, the bridge was constructed using local materials, including high-early-strength Type III cement from Lafarge for the precast, prestressed concrete sections. Widely specified in precast and prestressed concrete, Lafarge Type III cement’s high early strength allows forms to be reused more quickly than with conventional cement.
The innovative bridge design addressed environmental concerns by spanning the entire channel with no supporting structure in the river. The three-span structure includes two 120-foot-long approach spans and a 240-foot-long center span. Each approach span features 10 adjacent box beams cast with 8,000-psi self-consolidating concrete. The center span includes five modified New England bulb-tee girder lines, which were cast with a 10,000-psi self-consolidating concrete mix to meet the design demands on the large girders. The low-maintenance, highly durable concrete superstructure includes an eight-inch concrete deck with three inches of pavement and two six-foot-wide sidewalks that provide pedestrian access.
In addition to its strength in construction, the bridge also includes many aesthetic features that set it apart from typical highway crossings, such as cantilevered pedestrian outlooks over the river, architectural treatments on the abutment and retaining walls, precast ornamental bridge pilasters, decorative lighting, and unique concrete pier geometry inspired by the Brooklyn Bridge.
Lafarge North America Inc. (“Lafarge”) has close to 200 industrial and distribution sites and approximately 2,600 employees in 39 states in its U.S. Cement, Aggregates and Concrete businesses. Lafarge U.S. is an operating unit of Lafarge North America Inc. Lafarge is committed to contributing to Building Better Cities and being active in local environment, education and sustainable construction partnerships including the Wildlife Habitat Council, Habitat for Humanity and the National Building Museum. More information is available on the Lafarge North America website: www.lafarge-na.com.
Lafarge S.A., together with its subsidiaries (the “Lafarge Group” or the “Group”), is the world leader in building materials and employs 64,000 people in 62 countries, and posted sales of €15.2 billion in 2013. As a top-ranking player in its Cement, Aggregates and Concrete businesses, the Group contributes to the construction of cities around the world, through its innovative solutions providing them with more housing and making them more compact, more durable, more beautiful and better connected. Lafarge North America Inc. and its subsidiaries, including Lafarge Canada Inc., are Lafarge Group companies, and together constitute the largest diversified supplier of construction materials in the United States and Canada.
With the world’s leading building materials research facility, the Lafarge Group places innovation at the heart of its priorities in order to contribute to more sustainable construction and to better serve architectural creativity. Since 2010, the Group has been part of the Dow Jones Sustainability World Index, the first global sustainability benchmark in recognition of its sustainable development actions. More information is available on the Lafarge Group’s website: www.lafarge.com.