THE CONCRETE BRIDGE MAGAZINE

SUMMER 2017

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.

Issue link: http://www.aspiremagazinebyengineers.com/i/844035

Contents of this Issue

Navigation

Page 33 of 55

C O N C R E T E B R I D G E T E C H N O L O G Y 32 | ASPIRE Summer 2017 be designed and how other codes 2,3 are applied. It also offers suggestions to the designer regarding the fabrication and constructability of bridges and structures. The BDM covers a wide array of topics regarding ABC. But the focus of this article will be project delivery methods and the precast concrete bent system. How We Got Here Washington state has vast natural beauty and is also one of the faster growing places in the country. With a desire to add transportation capacity and protect the unique beauty of the state, precast concrete bents diminish the seemingly offensive activity of road construction. Whether it be minimizing traffic disruption, minimizing worker s' exposures to hazards, or optimizing time for fish migration, erecting bridge piers and cap beams quickly is in everyone's best interest. Like design-build (DB), what makes a project an attractive candidate for ABC is reduced construction time. DB offers time savings by overlapping design and construction efforts, and by encouraging c o l l a b o ra t io n . A B C s p e e d s u p t h e construction time by overlapping linear- flowing construction activities. This can be accomplished by prefabricating bridge components off-site while other activities ar e ta king p la ce on -si te, al lowing construction tasks that used to be done one after the other to be done at the same time. Th e c o n s t ru c t io n m a n a g er / g e n era l contrac tor projec t deliver y method capitalizes on a specific contractor's skills. While it may not provide delivery as rapidly as DB, it too complements ABC. Prefabricating bridge components to a specific contractor's interests and abilities offers a boost of speed because the d etails are optimized for that contractor's expertise. When to Use ABC Decisions affecting the choice to use ABC are often made by a traffic engineer or a project manager early in a project's d evelopment. Thes e individuals are often interested in concepts and project schedules, not structural details. By the time a bridge is being designed, the opportunity for a bridge design engineer to apply ABC has often passed. ABC ought to be presented to decision makers early in the project's development. To aid a WSDOT region engineer in deciding whether or not to apply ABC, the WSDOT BDM offers a design impact ques tionnaire and an ABC decision flow chart. These tools were borrowed from the California Depar tment of Transportation. The questionnaire uses a weighted scoring system based on the relevance and priority of concerns Accelerated bridge construction (ABC) has been a par t of the Washington State Department of Transportation's (WSDOT's) bridge design philosophy before the term was popularized in recent years. Washington state has a long history of pushing the envelope and trying new and innovative bridge designs. With the recent attention given to ABC, WSDOT decided to embrace this new movement and formalize their position on the topic. The WSDOT Bridge Design Manual 1 (BDM) is unique. Like many states, WSDOT's BDM provid es s tandard construction drawings. But it also puts an emphasis on standardizing design techniques. Being in a part of the country w here bridge designs are typically dominated by seismic analysis, it can be difficult to create broad-range construction standards. So, the BDM often relies upon standardizing how a bridge ought to Broad-based ABC Policy: WSDOT's Bridge Design Manual by Patrick Gallagher, Alpha & Omega Group (formerly with Washington State Department of Transportation) Erection of precast concrete crossbeam at Nalley Valley Interchange, Tacoma, Wash.. Photo: Geoff Swett, Washington State Department of Transportation.

Articles in this issue

Archives of this issue

view archives of THE CONCRETE BRIDGE MAGAZINE - SUMMER 2017