Construction Systems

 

Date of this Version

2011

Comments

Published by Jensen, Fischer & Shen in American Professional Constructor (2011) 35(2). Copyright 2011, American Institute of Constructors.

Abstract

Delivery of construction projects in the United States has traditionally been based upon the design-bid-build system. TIlis system has been used to create numerous impressive structures, but it often proves expensive and usually requires considerable time, because design, permitting and construction are accomplished in sequential order and do not overlap. Several alternatives to the traditional system have been developed, many of which fall under the classification of time-sensitive project delivery systems. The most commonly used time-sensitive project delivery systems are phased and fast-track construction (FaZio, Moselhi, Theberge & Revay 1988a). Figure 1 illustrates some of the major differences between traditional design-bid-build and two time-sensitive project delivery systems.

Phased construction is carried out by overlapping work packages, such a, excavation, foundations, structural steel, etc. Each work package is completed by the designer(s) in chronological sequence, with early activities beginning (or sometimes completed) before design is finalized for later work. Design and construction within a single work package do not overlap (Fazio, Moselhi, Theberge & Revay 1988b).

Fast-tracking is accelerated phased construction. Design and construction activities within individual work packages are overlapped to further reduce project duration (Fazio et al 1988b). Since the total scope of work for some activities is unknown until relatively late in the design process, bidders must often formulate estimates based, at least partially, upon anticipated quantities. When fast-tracking a project for construction, the owner must ensure that contract documents completed later in the design process are consistent with documentation used to begin actual construction.

Time-sensitive construction focuses on integrating design, permitting, and construction schedules to capture some of the time lost in the traditional design-bid-build environment. Time-sensitive construction does not shorten the length of time required to complete the individual tasks of creating plans and drawings, acquiring building permits, or actual construction. Instead, design and construction professionals are integrated into a collaborative environment where many of these tasks can be completed (at least somewhat) concurrently.

Rather than the fragmented levels of responsibility which exist under the traditional design-bid-build contracts, phased and fast track contracts often assign responsibility for all details of design and construction to a single entity. This contractual arrangement, known as design-build or design-

Phased and fast-track construction, while not focused on reducing construction cost, often produce savings for the owner and/or contractor. The combined effects of paying for a construction loan (which usually has a higher interest rate than more permanent financing) and an earlier completion date (which can save labor hours) may enhance the overall profitability of a proposed project to the extent that an economically infeasible endeavor can be transformed into reality (Russell & Ranasinghe 1991).

The traditional system of granting legal approval (a permit) to construct a project was, however, created in the early 20th century. This system was designed specifically to protect the public's safety, health and general welfare from less than adequate design, materials and workmanship sometimes encountered when using the traditional design-bid-build project delivery system. The traditional building permitting system, although sometimes viewed as slow, cumbersome and expensive, has proven itself versatile, flexible and responsive to protecting the safety, health and well-being of the public.

When applying for a traditional building permit, all plans, drawings and specifications must be completed, reviewed and approved prior to a full permit being issued. Under the limited scope permitting process now being applied to many time-sensitive projects, construction is divided into different work packages consisting of chronologically phased activities. Only the plans, drawings and specifications pertaining to a specific package must be completed, submitted and approved prior to work beginning on activities within that package (City of Lincoln 2008). An additional limited scope permit is required for each subsequent work package.

The ad vantages inherent in time-sensitive construction have convinced many US municipalities to legally recognize one or more of its variants as a legitimate delivery system for new construction (City of Ithica 2000; Los Alamos County 2006). Other jurisdictions restrict time-sensitive construction to alteration or repair work (City of Columbus 2009). A third set of municipalities recognizes that time-sensitive construction can be appropriate for both new construction and for renovation work. The most common method of legally authorizing time sensitive construction is use of a limited scope permit. The limited scope permitting process is being used by other municipalities to encourage economic growth and competitive development. Afaster and more efficient permit process designed to accommodate developing and expanding businesses provides an incentive for new business and industry to locate in the local area and for existing businesses to expand (City of College Station 2004).

Municipalities are, however, reluctant to incur additionalliability as the result of limited scope permitting. The City of Lincoln's building code specifies" ...you will receive only one set of plans endorsed by stamp indicating that you may, at your own risk, place footings and foundations to grade level only and place underground utilities ... " (City of Lincoln 2008). This wording is an example of a municipality using the limited scope permit to distribute risk among the contractor, designer( s) and owner. These three parties are assuming the risk for placing utilities, foundations and/ or footings because the municipality has no method of checking whether or not the footings, foundations or utilities will conform to the minimum code specifications required for the completed structure. The limited scope permit thus protects the municipality should the utilities, footings or foundations not comply with parameters required by building code for the eventual use of the structure.

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