The Rockingham I-91 Bridges project in the northeast US state of Vermont has picked up a Precast Concrete Institute 2021 Design Award.
The twin structures were honoured in the transportation category “best bridge with a main span of more than 150 feet” – 45.7m – in length.
The Precast/Prestressed Concrete Institute (PCI), founded in the state of Florida in 1954, is the technical institute and trade association for the precast and prestressed concrete structures industry in the US. The PCI is now based in Chicago. The PCI Design Awards programme, in its 58th year, recognises design excellence and construction quality using precast concrete.
The 2021 award to HDR is the third year in a row that a transportation project by the engineering consultancy, has been honoured. Previous HDR winners include the Marc Basnight Bridge in the state of North Carolina and Project Neon in Las Vegas – both awards given in 2020 - and the Governor Mario M. Cuomo Bridge in New York in 2019.
The bridges in Rockingham take interstate class highway I-91 over the Williams River, replacing two bridges that were built in the 1960s and which were showing signs of advanced deterioration. HDR was the design-build engineer of record on the project, responsible for the complete design of the two replacement bridges, the associated road work, maintenance of traffic and coordination of environmental permitting.
Each bridge is a four-span spliced precast concrete girder structure — a first in Vermont. The Vermont Agency of Transportation had initially prepared a precast concrete balanced cantilever base technical concept. During the proposal phase however, HDR’s team evaluated all applicable bridge solution types and determined that a haunched, spliced precast girder solution was the most efficient and cost-effective.
The spliced design and material choices, such as stainless steel reinforcing in the pier caps and deck, combined to give the bridges a 100-year service life - 25 years longer than standard for other bridges in the area. The bridges, which will be completed in the summer of 2021, also feature massive prestressed concrete beam segments of up to 93 tons (around 85 tonnes), maxing out the lifting capacity at the plant that produced them.
“These bridges will connect the people of Vermont for the next 100 years, and it’s humbling to realize the part that we will play in so many lives in the coming decades,” said Thomas French, senior project manager with HDR.
The old Rockingham Bridges, owned by Vermont Agency of Transportation (VTrans), provide a vital link for south and central Vermont, but age and heavy traffic took their toll on the twin four-span deck truss bridges. Known locally as the High Bridges, the two were built in the 1960s and were in poor condition. An engineering study determined that the most long-term cost-effective solution was to replace both bridges.
HDR has been design-build engineer of record on the US$50 million project since 2016. The company, based in city of Omaha in the state of Nebraska, is responsible for the complete design of two replacement bridges and the associated road work. HDR also led a team responsible for seismic analysis, geo-technical evaluation, hydraulic and scour analysis, environmental permitting, public relations and traffic control.