The National Academies Press

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Pages 244-268

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From page 244... ... 244 Focus Group and Survey Results First Owners Survey Results The owners survey was created to gain insight into the successful practices of bridge owners engaged in accelerated bridge construction and to learn about the challenges faced by bridge owners who have not been successful with ABC. The survey contains 40 questions that focus on ABC goals, practices, experiences, hindrances, and opinions. Read the entire page →
From page 245... ... 245 from ABC information sessions, as the lack of information on ABC has been identified as a hindrance for many agencies. When states lacking experience in ABC methods were queried, the top reason cited for unsuccessful implementation of ABC was a lack of funding. Read the entire page →
From page 246... ... 246 ABC has distinct benefits that are definitely attractive to many agencies. However, despite the gradual lowering of costs and life-cycle cost savings, DOTs are hesitant to use ABC techniques because of their higher initial costs. Read the entire page →
From page 247... ... 247 Missouri Individuals at the Missouri DOT cited various examples of recent ABC deployment, including their frequent use of stayin-place concrete deck panels, the successful use of Inverset systems, and a long bridge redecked with full-depth precast deck panels with nighttime closures. They also cited the use of adjacent box beams with a concrete topping erected as an emergency replacement and the application of latex-modified high-early-strength wearing surfaces in lieu of conventional overlays as a way of expediting highway reopening times. Read the entire page →
From page 248... ... 248 organization's practices. When the department has tried to accelerate projects, its own construction engineering department has been reluctant to support the schedule. Read the entire page →
From page 249... ... 249 As funding is currently structured, the owner has no financial incentive to use rapid renewal methods other than staged construction. The Texas DOT districts are limited to using only 5% of the project cost for incentives. Read the entire page →
From page 250... ... 250 contractors have demonstrated a willingness to get into the precasting business. The projects let to date have demonstrated a 5:1 to 6:1 ratio of user costs saved to construction costs incurred. Read the entire page →
From page 251... ... 251 and techniques in its bridge replacement program. In California, ABC is considered to be only one part of accelerated project delivery (APD) Read the entire page →
From page 252... ... 252 Georgia The Georgia DOT has some experience with ABC, having completed one such project in the past 5 years. The use of ABC methods needs to be required, and use of ABC is left up to the contractor in general. Read the entire page →
From page 253... ... 253 experience of completing ABC projects in general. Standardization could make ABC methods more accessible to designers and would help contractors gain meaningful experience; both would help lower costs and improve quality in the long term. Read the entire page →
From page 254... ... 254 kept to a minimum. ABC is viewed favorably in South Dakota if project conditions warrant its use. Read the entire page →
From page 255... ... 255 Georgia: There was a Highways for LIFE project that used ABC, but the contractor said it could do it in the same amount of time with standard methods (i.e., cast-in-place) despite time requirements. Read the entire page →
From page 256... ... 256 Question/Topic Do you have any issues pertaining to design for ABC? Discussion Points Georgia: The problem of precast connections is a big issue, but the FHWA connection manual is good and engineers at the Georgia DOT are finding it useful. Read the entire page →
From page 257... ... 257 The University of Maine in Orono has tested it to failure, and it performed exactly as predicted. Maine also has a "Bridge in a Backpack" concept that involves tubes of FRP filled with concrete set in place, and uses FRP decking filled with concrete. Read the entire page →
From page 258... ... 258 Texas: Some CIP allows for better control of curve. Tennessee: Posttensioning is a problem. Read the entire page →
From page 259... ... 259 Discussion Points Texas: It costs the contractor more to build it faster, so we need to figure out how to set it up so that it takes fewer resources to accomplish. Tennessee: If it is a viable system and is economically advantageous, the marketplace will discover it. Read the entire page →
From page 260... ... 260 Montana: Montana is another rural state, but it is trying to define a class of projects that is fit for ABC, as there is a use for ABC in a rural environment. As part of that process Montana wants to look at projects early on to see if they're appropriate for ABC. Read the entire page →
From page 261... ... 261 California: While we were promoting ABC in various districts, ROW [right-of-way] , environmental, and traffic people were extremely interested in the applications of ABC to their respective fields, and this led to a lot of increased interest. Read the entire page →
From page 262... ... 262 The team was curious as to contractor opinions about the engineer of record providing information on assumed asdesigned erection sequences. One of the premises of this research is that engineers will be contemplating potential innovative erection sequences on future ABC projects and designing the structure for at least one unique erection method. Read the entire page →
From page 263... ... 263 all projects, and contractors who don't have access to inhouse or on-call specialty engineering will potentially be unable to bring innovation to small projects. In addition, the process for teaming designers and contractors as it is currently practiced is not user-friendly. Read the entire page →
From page 264... ... 264 by as much as 6 months. Any current bridge design (new or replacement) Read the entire page →
From page 265... ... 265 developed a top-down construction system that allows for bridge placement without the need for any ground-mounted equipment. This system minimizes environmental disturbances and provides a more economical placement system on certain types of projects, specifically those with multiple long segments with site constraints. Read the entire page →
From page 266... ... 266 stEEl shElls Encasing concrete in steel is an alternate approach to composite action. Piers and columns could use steel as stay-inplace forms to shield concrete, especially in high-impact areas. Read the entire page →
From page 267... ... 267 ComPositE PrECAst ConstruCtion The Willis Avenue Bridge in New York City used precast boxes as so-called sacrificial forms, which also allowed for aesthetic features to be cast in. This process can have schedule benefits. Read the entire page →
From page 268... ... 268 accomplish ABC is "getting the engineering and detailing right." Having a senior designer with decision-making ability on site to answer questions quickly would help. With regard to standardization, several elements have the potential to be standardized easily: precast concrete box beams, precast concrete barriers, and precast vertically posttensioned pier elements. Read the entire page →

From page 244...

... 244 Focus Group and Survey Results First Owners Survey Results The owners survey was created to gain insight into the successful practices of bridge owners engaged in accelerated bridge construction and to learn about the challenges faced by bridge owners who have not been successful with ABC. The survey contains 40 questions that focus on ABC goals, practices, experiences, hindrances, and opinions.