0 African Journal of Earth and Environmental Sciences Volume 2, No. 2., December, 2020, xxx-xxx Comparing Performance Quality of Design-Bid-Build (DBB) and Design-Build (DB) Project Delivery Methods in Nigeria Danlami Ebenezer Salla Department of Quantity Surverying, Bayero University, Kano. Kano State ABSTRACT Design-bid-build (DBB) and design-build (DB) are two prevalent construction project Article History delivery methods widely used in various countries of the world. Researches have generally compared these methods in terms of project quality, neglecting a very important quality Received: 17 February 2020 dimension; performance quality. This paper aims at comparing the perception of Received in revised form: 19 April 2020 construction professionals on performance quality of DBB and DB. It is based on a set of Accepted: 13 March 2020 Published Online: 9 September 2020 primary data from manually distributed research questionnaire to professionals in the built-environment, comprising of architects, builders, engineers and quantity surveyors. Keywords: Using the sampling table, a sample size of 350 was computed. A total of 140 questionnaires (were drawn from professionals who were employed in clients’ organizations Performance Quality, Design and Build (DB), Design-Bid-Build (DBB), Project (N52), contracting firms (N47), and consultancy firms (N41). Frequency counts of their Delivery, Nigeria responses were obtained and computed, from which the mean item score for each Corresponding Author Contact: performance quality criterion was computed to obtain their Relative Importance Indexes, Danlami Ebenezer Salla RII. Inferential statistical test was computed for responses of each of the groups and for the Email: [email protected] overall groups combined about performance quality criterion for DBB and DB. According DOI: 10.11113/ajees.v3.n1.104 to the professionals, DB outperforms DBB in terms of performance quality in Nigerian construction industry. Design & build method should therefore be promoted by public and private client alike. Public clients are encouraged to adopt Design & Build method in the delivery of their building construction projects, although not well supported by the subsisting public procurement laws in Nigeria. Performance Quality should be clearly defined at the early stages of building construction projects in Nigeria. 1.1 INTRODUCTION been compared largely in terms of project The choice of construction project delivery quality (Idiake, Shittu, Anunobi, & Akanmu, method is an important decisions that has a 2015; Pandit & Yadav, 2014), but an critical effect on project performance and important quality dimension; performance construction quality (Al Khalil, 2002; Park, quality (Watermeyer, 2010), has generally Lee, Kim, & Kim, 2015). Numerous studies been neglected in previous studies. (Yasamis, Arditi, & Mohammadi, 2002; Alzahrani & Emsley, 2013; Chang, 2016; 1.2 Concept of Design and Build and Jelodar, Yiu, & Wilkinson, 2016; Sullivan, Design-Bid-Build Asmar, Chalhoub, & Obeid, 2017) have been Under the design and build, the contractors conducted on enhancing the optimization in typically make decisions and carry out the the selection process of design-bid-build (DBB) works based on co-operation and coordination and design-build (DB) by simple comparison. (Ramus, Birchall, & Griffiths, 2006). DB and The design-bid-build and design-build, have DBB methods exhibit varying characteristics Volume 2, No. 1., June, (2020), 517-523 |[email protected]| and consequently have different advantages and dimensions with relevant strategies based on disadvantages. Therefore, the project different delivery methods (Morledge & Smith, participants may undertake unique quality 2013). Figure 1: Conceptual model for DBB and DB Source: Ashworth & Perera (2015) In DBB, the project owner divides project between the designer and the contractor; the tasks into two parts (i.e., the design two parties typically make decisions and component and the construction component) complete their work independently. However, and separately awards them to two entities in the DB method, the owner contracts the (i.e., a designer and a contractor). Figure 1 entire project to only one entity (a DB simplifies the DBB and the DB delivery contractor) that undertakes all the design and methods, with their unique attributes. As construction tasks of the project (Group, shown, no contractual relationship exists Mahdi, Riley, Fereig, & Alex, 2002). Table 1 Comparison between the DB and DBB Delivery Method (Chen, Zhu, & Zhang, 2009) Volume 2, No. 2., December, (2020), xxx-xxx |[email protected]| 1.2.1 Design-Bid-Build Since the mid-1940s, the architect‘s (Traditional Method) nomination and/or appointment of the Design-bid-build (DBB) remains the quantity surveyor has been gradually predominant delivery method for construction superseded by appointment by the Employer, services in the United Kingdom as well as sometimes before the selection of the architect many parts of the world (Morledge & Smith, and, in some cases, the latter‘s selection is 2013), with low-bid procurement being the made on the recommendation of the quantity predominant method for selecting construction surveyor. firms (Sullivan & Guo, 2009; El Asmar et al. 2010; Ballesteros-pérez, Skitmore, Pellicer, & 1.2.2 Design and Build Gonzalez-Cruz, 2015; Schöttle & Arroyo, Design and build projects aim to overcome the 2017; Nguyen, Lines, & Tran, 2018). problem of having separate design and However, increasing numbers of owners are construction processes by providing for them inclined to adopting alternative contracting within a single organization (Morledge & methods, such as design-build (DB) and Smith, 2013). The single firm is generally the construction manager at risk (CMAR), for building contractor, who may employ the better project performance (El Asmar et al. designers in-house or be responsible for 2016; Carpenter & Bausman 2016; Sullivan et employing consultants directly under their al.2017). Because procuring a qualified control. The major difference is that instead of contractor greatly affects the performance of approaching the designer for a building, the the project (El-Wardani, Messner, & Horman, employer briefs the contractor directly. The 2006; Carpenter & Bausman, 2016), from employer may choose to retain the services of early nineteenth century until about the 1950s, an architect or quantity surveyor to assess the the ways by which building projects were contractor‘s design or to monitor the work on promoted and carried out in the UK site. The prudent employer will always want conformed to straightforward and well-tried some form of independent advice. The design procedures. evolved by the contractor is more likely to be suited to the needs of the contractor‘s If the project was small, the building owner (or organization and construction methodology, ‗Employer‘, as he is often called) employed a and this should save construction time and building contractor to design and construct the construction costs. Some argue that the design building for him. Because buildings generally will be more attuned to the contractor‘s conformed to a well-defined pattern, construction capabilities, rather than the design contractors had within their organizations the requirements of the employer. The final full range of expertise and skills normally building should result in lower production required. In the case of larger projects, the costs on site and an overall shorter design and Employer appointed an architect to design the construction period, both of which should building, and he then produced drawings and a provide price savings to the employer (Arslan, specification. If the architect considered it Kivrak, Birgonul, & Dikmen, 2008; Lines & necessary (and the Employer approved), he Kakarappalli, 2018). There should also be then appointed a quantity surveyor to prepare some supposed savings on the design fees, even a bill of quantities. Then, on the basis of either after taking into account the necessary costs of the specification and drawings or the bill, any independent architectural advice. A further contractors were invited to tender in advantage to the employer is in the implied competition to carry out the work. Usually the warranty of suitability, because the contractor lowest tenderer was awarded the contract. Volume 2, No. 2., December, (2020), xxx-xxx |[email protected]| has provided the design as a part of the all-in improvement, the scope of work, and the service (Ramus et al., 2006). efficiency of cooperation among different Design-bid-build (DBB) and design-build (DB) participants (Bausman, Chowdhury, & Tupper, are two prevalent delivery methods widely 2014). used in various countries such as China, In Konchar & Sanvido (1998), defined project Singapore, United Kingdom, and United States quality as ―the degree to which a facility meets (Chen et al., 2009). The choice of delivery expected requirement.‖ This definition of method is one of the most important decisions quality placed emphasis on the conformance to that can determine the quality of construction quality requirements and ignored the projects. Two basic delivery methods, design- importance of performance quality. In some bid-build and design-build, have been related studies, client’s satisfaction on DBB and compared in terms of project quality; DB projects was a major consideration. But however, an important quality dimension, key performance quality indicators such as performance quality, has generally been