THE CONCRETE BRIDGE MAGAZINE

SUMMER 2018

ASPIRE is a quarterly magazine published by PCI in cooperation with the associations of the National Concrete Bridge Council. The editorial content focuses on the latest technology and key issues in the Concrete Bridge Industry.

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S TAT E 38 | ASPIRE Summer 2018 V ermont is a mostly rural state, and many of its bridges are one-span structures less than 150 ft in length. Because bridge closures can lead to long detours, the Vermont Agency of Transportation (VTrans) often uses accelerated bridge constr uction (ABC) techniques to minimize traffic interruptions. Additionally, VTrans works with local communities to set construction schedules that accommodate their time frames. NEXT Projects and ABC A key component in most of Vermont's concrete bridges is the Northeast Extreme Tee (NEXT) precast concrete beam, which features a top flange that forms the structural bridge deck, eliminating construction steps so bridges can be quickly opened to traffic. VTrans first used NEXT beams in 2011, for the construction of a 65-ft span over the Williams River on State Road 103 in Chester. With NEXT beams, the bridge opened to traffic in four weeks. The alternative design would have required a temporary bridge and taken approximately nine months to complete. The minimal disruption to traffic proved that NEXT beams provide benefits, and they are now used regularly. NEXT beams provided an important tool when VTrans established its Accelerated Bridge Program (ABP) in 2012. ABC offers several benefits in the state, such as eliminating environmental concerns related to temporary bridges, limiting the impact of construction on rights-of-ways and utilities, and reducing burdens on detour routes. Since ABP's inception, VTrans has constructed or rehabilitated the superstructures on 79 bridges, with another three projects underway and 17 in the planning stage. Since 2012, about 50% of VTrans projects have been undertaken v i a A B P. A B P e m p h a s i z e s p r e fa b r i c a t i o n of component s and the use of incentive/ disincentive contract provisions that encourage new techniques and efficiencies. V Trans's Project Initiation and Innovation Team (PIIT), which was developed in conjunction with ABP in 2012, has developed many techniques to create efficient, consistent, and programmatic alternatives for rehabilitating or replacing deteriorated bridges and culverts. Tropical Storm Irene In 2011, Tropical Storm Irene damaged or destroyed many Vermont bridges, including s o m e t h a t h a d n o t b e e n s c h e d u l e d fo r replacement. The creation of ABP and PIIT and a boost in state funding helped return these bridges to service quickly. During the storm recovery process, Vermont b e g a n u s i n g a " c o r r i d o r " c o n s t r u c t i o n technique, in which a series of neighboring bridges are replaced at once. One of the first corridors was in Rochester, where Irene destroyed two of the four bridges and damaged another. VTrans's plan to replace all four bridges allowed one contractor to efficiently mobilize crews and materials. Two of the "Rochester Fast 4" bridges used single-span pretensioned concrete NEXT beams with a precast concrete curtain wall, while another featured an open-bottom arch with a cast-in-place (CIP) concrete subfooting and a precast concrete pedestal wall and concrete arch. (See "Rochester Fast 4 on VT 73," which appeared in the Fall 2016 issue of ASPIRE ® .) VTrans now uses this corridor approach wherever feasible. Planning and Feedback A rolling five-year plan helps determine the state's construction schedule (which Irene upended for several years). Over time, VTrans has become more efficient at setting key milestones in project timetables. To this end, VTrans uses scheduling tools to track every element, including environmental permitting and design progress. VTrans involves community members in every aspect of projects, including scheduling. For example, VTrans consults trucking firms that may be affected by detours and collaborates Vermont by Robert S. Young, Vermont Agency of Transportation In 2011, Vermont Agency of Transportation built a 65-ft-long bridge over the south branch of the Williams River on State Road 103 in Chester, marking the state's first use of Northeast Extreme Tee (NEXT) precast concrete beams. The NEXT beam has since become a standard design option in the state for fast construction. Photo: Vermont Agency of Transportation.

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