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I-15 Prefabricated Bridge Superstructure – Pioneer Crossing, Utah.
FHWA's Every Day Counts Initiative
M. Myint Lwin and Louis N. Triandafilou, Federal Highway Administration
For the Nation’s highway community, meeting the challenges of today’s transportation needs while working more efficiently, sustainably, and cost-effectively means going beyond innovation and ingenuity. It means making every day count. Rapid deployment of proven technology and solutions to speed up project delivery are at the heart of the Federal Highway Administration’s (FHWA) new Every Day Counts (EDC) initiative. According to FHWA Administrator Victor Mendez, EDC is designed to identify and deploy innovation aimed at shortening project delivery, enhancing the safety of our roadways, and improving environmental sustainability. EDC will initially focus on getting promising new technologies into the marketplace faster and speeding the delivery of major highway projects. Administrator Mendez has asked FHWA Deputy Administrator Greg Nadeau to lead this initiative.
The FHWA aims to make innovative contracting standard business practice by supporting the deployment of such accelerated project delivery methods as Construction Manager/General Contractor (CM/GC) and Design/Build. The EDC initiative will also provide several innovative approaches to improving the delivery process for projects that require an Environmental Impact Statement (EIS) or other environmental documents. EDC also features the following priority technologies that are intended to be implemented on a fast-track schedule over the next 2 years: warm mix asphalt, adaptive signal control technology, safety edge, geosynthetic reinforced soil integrated bridge system, and prefabricated bridge elements and systems (PBES). Many of today’s bridge construction and replacement projects take place in areas of heavy traffic, where detours and bridge closures severely impact the flow of people and goods on transportation corridors. One of the most common ways to accelerate bridge construction is to use PBES to construct bridges. These elements and systems are prefabricated off-site or adjacent to the final bridge alignment ahead of time, and then moved into place when needed, resulting in closure of the bridge and highway for only a short duration. Very frequently, these PBES are constructed using conventionally reinforced, pretensioned, or post-tensioned concrete or a combination thereof, for superstructure and substructure members.
The use of concrete PBES results in several key benefits that fit the EDC initiative, such as reduced on-site construction time; minimal disruption to the traveling public; improved safety of the traveling public, contractor’s work crews, and the owner’s inspection teams; less disruption to sensitive environments; improved quality of the finished product; and lower initial and life-cycle project costs.
Contractors can improve quality of finished concrete products by prefabricating them in protected environments, thus avoiding harsh weather conditions. In a protected environment, suppliers are able to produce a consistent quality of ready-mixed or precast concrete products. Standardized plant operations result in a consistent quality of production. Within a protected environment, the producer can attain optimal curing of concrete elements, without having to deal with the costly and time-consuming requirements of cold- or hot-weather concreting. Many concrete bridges already employ high performance concrete (HPC) to enhance durability and may use high strength concrete to achieve longer span lengths and eliminate piers. Thus, the implementation of PBES to accelerate bridge projects is tailor-made to continue the national implementation of HPC that state departments of transportation (DOTs) have been aggressively pursuing.
Depending on the size of the concrete superstructure and substructure PBES, various means and placement techniques can be deployed to accelerate bridge projects. These include the use of self-propelled modular transporters (SPMTs), as depicted in the photograph, longitudinal launching, and transverse sliding or skidding. These techniques are applicable to both single-span and multi-span bridges. For short span structures, which make up the majority of the National Bridge Inventory, conventional equipment can be used.
HPC superstructure and substructure PBES can play an important role in helping the state DOTs achieve the national goals that FHWA is considering as part of the EDC initiative. Two of these goals still in draft form are as follows:
FHWA’s EDC initiative emphasizes an improved driving experience for the American public, through rapid deployment of several proven technologies and solutions to speed up project delivery with minimal disruption to traffic. PBES using HPC elements will continue to demonstrate that bridges can be built better, faster, and safer, all in a manner that results in beneficial benefit/cost ratios when taking into account road user costs.
More information about EDC is available at the FHWA website www.fhwa.dot.gov/everydaycounts/ or contact your local FHWA Division Office.
HPC Bridge Views, Issue 65, Jan/Feb 2011