The attainment of acceptable levels of quality in the construction industry has long been a problem. In construction projects, huge expenditure of time, money and resources; both human and materials are wasted each year simply because of inefficient and non-existent of quality management procedures. When issues affecting construction quality are being addressed, little emphasis is placed on design factors.
Yet, most of the decisions affecting the constructability, performance and operations of the project as a whole are taken right at the design stage. Unfortunately, response factors causing significant problems at later stages of project have been linked to inadequacies at the conceptual-design stage of the project. This prompted a lot of earlier studies into the identification of issues bordering on the implications of inefficient designs. One of those is the study by the Building Research Establishment, UK (BRE, 1982), where it showed that a little more than 50% of failures or faults in construction were as a result of design deficiencies.
In addition, the National Economic Development Office (NEDO, 1987) also acknowledged the fact that inadequate qualities on construction sites were due to design inefficiencies but by a whooping two third of the cases. These are pointers to the fact that design process has huge influence on the achievement of quality on construction sites. While there is no consensus on the set of design factors affecting quality of building projects, some factors mentioned below rank high in adversely affecting quality delivery on construction sites:
§ Poor client briefing
Quality in a simple term refers to the conformance to client's brief. Without a second thought, the most important phase of the project life cycle is the client-briefing stage. In the words of Blyth and Worthington "a brief is the gauge at which the rest of the project development is measured, specifying the building quality among other requirements". In as much as the client's brief sets the stage for quality of project, factors like clarity of project mission, competency of the client in giving project brief, making moral decisions, defining roles et cetera should be given a clinical look. Researches have shown that those factors mentioned above have significant influence on the quality of projects.
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| Engr Tunde Salami R. Eng |
§ Lack of project definitions
For a proper design, the formality required of project scope definition has to be available and clearly expressed. The absent of this at the design stage leads to vagueness in the understanding of the project requirements. As such, different stakeholders will have a different understanding of what is in and what is out of scope. At the end of it all, the quality of construction suffers and project disputes eschew.
§ Inadequate involvement of other professionals and team work during design stage
In studying the total quality management (TQM) application on construction projects in the United States, Gunaydin (1995) come to the conclusion that the extent of a team's participation in the design stage is the most important factor affecting project's quality. This buttresses the fact that the early involvement of the design team and cohesiveness between its members during the design stage among the trades (Architects, Civil, Structural, Mechanical and Electrical Engineers) is crucial in the achievement of overall project quality.
§ Design defects
In order to maintain the required levels of accuracy and constraints of time, common human errors are inevitable and can lead to huge design errors. These errors affect not only the quality of design and construction works but also the safety of workers.
What are design errors?
Design errors in a general sense refer to design mistakes, design omissions, and design conflicts.
Design mistakes or flaws are human errors that are natural and unavoidable. An inexperienced designer applying the design information wrongly could pass for a design mistake/flaw. These mistakes can be from poor memory (lapses) or failure arising despite correctness of knowledge (slips).
Design omission happens when a crucial part of the whole system is forgotten during the design stage.
Design conflicts are intersecting items that cannot be simultaneously constructed.
§ Design Changes
Design change can occur either during the design phase or during the construction phase. The effect during the latter phase is hugely detrimental because it weighs heavily on time, cost and performance (quality) of the project. An example of a design change and its effect during construction is the change in the concept of the Kuala Lumpur International Airport 2 (KLIA2). During construction, the design concept changed and as a result, the project cost rose steeply from RM 1.7billion to RM 4 billion… Just like that! , not to talk of the lost time and the quality of work. Hiyassat (2000) reported that design changes during construction process lead to delay, variation order and claims.
Design change during the design phase might seem controllable and allowed, however, if the changes are in their numbers, there might be a loss of quality during the construction phase. According to Love and Irani (2003), design changes can affect the aesthetics and functional aspects of the building; the scope and nature of work, or its operational aspects. The design should be reviewed thoroughly to check for its constructability and desired quality when there is a design change. With any design change, the process of review checking for constructability and the desired quality must be repeated. Constructability reviews as recommended by the Construction Management Association of America (CMAA, 1999) should be periodical throughout the design phase, in order to check for mistakes, omissions, and checkpoints. This is to ensure that the project comes with good quality and standard.
§ Lack of proper constructability review of design
The absence of an integrative approach to the design and construction processes is responsible for many problems like time delay, cost inefficiencies, bad construction quality and so much more. The integration of the design and construction processes is greatly hinged on the project delivery method adopted. It a well-known fact that the design-build (DB) is a better project delivery method with regards to integration of design & construction phases and constructability than the design-bid-build (DBB) delivery method. Throughout the industry, constructability reviews are consistently performed, however, with mixed results. These myriads of results are impelled by many factors but the most predominant among them are the experience level of the reviewing designer or engineer and the time specified to complete the review. In most construction management companies, this task of constructability reviews are given to young project engineers; simply because the more experienced senior engineers or executives do not have the time.
Why?
The design schedule and bidding process time are short, hence the time allotted to constructability review is customarily shorter.
The unfortunate reality is that this extremely important task of constructability review is given some days, a period not enough to gain intimate knowledge of the project, much less review and understand niceties. There is a misconception about constructability review, that it should be completed in time for ALL solutions to be incorporated in the bidding documents. This is untrue. While the incorporation of all the solutions before bidding will be an optimal target, the truth is, it is not a realistic expectation. This is not in any way saying that important problems should not be addressed early, but thorough reviews cannot be completed in time to be incorporated into the design documents for bid.
There are still more factors coming in the next part.... To be Continued..
About the Author;
Babatunde SALAMI, PMP, R.Eng (COREN), LEED Green Assoc. is a Project Manager (Infrastructure),Projects Department,KFUPM, Saudi Arabia
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