Budget and Schedule-Related Critical Success Factors for Design-Build Water and Wastewater Projects: Principal Component Analysis

Abstract

The United States confronts significant challenges within the water and wastewater sectors. According to the American Water Works Association (AWWA), a capital investment of $1.3 trillion is necessary for the repair and replacement of water infrastructures in the United States over the next 25 years. As alternative delivery methods are new in the water and wastewater sectors, the utility owners lack expertise and experience in executing these delivery methods. Thus, it is important to investigate the critical success items and factors of Design-Build (DB) methods, thereby ensuring that projects are completed within scheduled timeframes and budgets with better quality. To address this need, the present study undertakes a comprehensive literature review to identify the critical success factors associated with DB methods. Subsequently, a survey is conducted among both public and private utility owners to rank these items. The study identifies top critical success items related to completing projects within schedule and budget. Through principal component analysis, five budget- and schedule-related critical success factors were extracted. The outcomes of this study are the top critical success items and factors, thereby providing valuable insights for water and wastewater utility owners to focus on these items and factors intensively and help them execute the projects with great success.

1. Introduction

Water and wastewater facilities play a significant role in determining the status of a nation’s health [1]. However, the US has been facing challenges in this sector due to the aging of water and wastewater infrastructures [2]. Typically, wastewater treatment plants have an operational lifespan of 15 to 20 years, while sewer networks are designed to last approximately 50 years, but many of the existing wastewater systems were constructed over half a century ago [1]. Similarly, as indicated by the American Water Works Association (AWWA), a substantial proportion of subsurface drinking water infrastructures has surpassed their intended operational lifespans, having been constructed 50 years ago or more [3]. The findings of this investigation further reveal a compelling need for a $1.3 trillion capital investment over the ensuing 25 years to address the imperative for repairing and replacing water infrastructures in the United States. Further, delaying this type of investment might lead to a decline in water quality, an increase in water outages, and a rise in the price of emergency repairs [3]. In 2017, the American Society of Civil Engineers assigned a grade of “D” to water infrastructures and a grade of “D+” to wastewater infrastructures [2,4]. This report additionally conveys that the United States encounters 240,000 annual occurrences of water main breaks, and the essential capital investment required for the enhancement of the nation’s wastewater and stormwater infrastructure is estimated at $271 billion over the ensuing 20 years [4]. AWWA’s most recent annual poll revealed that the top problems facing the water community were infrastructure renewal and replacement, capital improvement financing, and long-term drinking water supply [5].

To address these challenges in the water sector, efficient project delivery methods are needed that can simplify processes and ensure timely, cost-effective solutions. In response, the construction industry has adopted new methods such as Design-Build (DB), which are increasingly popular across sectors due to their ability to improve efficiency, manage risks, and enhance project outcomes. Unlike the traditional Design-Bid-Build (DBB) approach, DB fosters integrated, collaborative processes that can better support the water sector’s complex infrastructure needs [6,7].

In alignment with conventional practices in construction projects, water and wastewater facilities have been implemented utilizing the conventional DBB method because of its familiarity and widespread use. However, this approach has limitations, such as providing only one engineering solution, focusing on short-term goals based on available funds, and often selecting contractors based on the lowest bid, while designers may have limited exposure to new construction technologies that can reduce flexibility and innovation in completing projects [2,8,9]. These limitations, combined with the evolving procurement laws and proven efficacy of alternative delivery methods, are motivating owners to favor methods like DB [1,2]. Alternatives like these provide flexible project financing and management, bring integration and innovation, and select contractors based on price as well as quality [2,8].

Despite their advantages over traditional approaches, these delivery methods are relatively new, and water and wastewater utility owners often lack the expertise and experience needed to implement them effectively. Thus, it is important to investigate the DB methods’ critical success items (CSIs) and factors (CSFs) so that the projects can be completed within the scheduled time and budget with better quality. This study conducts a comprehensive literature review of the DB methods’ CSIs and a survey thereafter among the public and private utility owners to rank these factors. The top-ranked CSIs will be identified according to the survey. Also, the number of CSFs that contribute to completing DB water and wastewater projects within budget and schedule will be constructed. These findings can serve as valuable guidance for water and wastewater utility owners, enabling them to concentrate intensely on these CSIs and CSFs and facilitating the successful execution of projects.

2. Literature Review

The construction industry has increasingly adopted alternative project delivery methods, such as DB, to address complex regulatory, technical, and stakeholder demands. Research indicates several CSFs for these methods. Effective project management practices, including comprehensive planning, resource optimization, and clear communication, are fundamental to achieving efficiency and project goals [1,6,10]. Strong client capabilities in decision-making and leadership also significantly influence outcomes, ensuring alignment with the project vision and timely resolution of challenges [11,12]. Leadership competency and skilled, committed teams contribute to maintaining focus, driving performance, and bringing necessary expertise to design, compliance, and execution phases [7,12].

A collaborative and adaptable organizational culture fosters trust and innovation, enabling better integration among project participants and improving outcomes [13]. The utilization of advanced project management systems enhances coordination, process alignment, and efficient communication across different project stages [10,14]. Successful project execution in DB methods further depends on factors like clear design briefs, authoritative and decisive leadership, and shared understanding of project objectives among stakeholders [2,12]. Establishing trust and seamless integration within the project team encourages open communication and knowledge sharing, which are vital for responsiveness to project challenges [15].

An experienced multidisciplinary team, supported by a well-organized structure, enhances communication, decision-making, and accountability [16]. The team members’ qualities, including organizational and leadership skills, significantly affect project performance [12]. Competent contractors and clients who can effectively adapt to project-specific requirements ensure smoother operations and better financial performance [12,15]. Comprehensive risk and liability management strategies help in proactively addressing challenges, promoting resilience throughout the project lifecycle [11]. Maintaining clarity on end-user requirements and project scope prevents scope creep and aligns efforts with intended deliverables [6,15]. Thoroughly evaluating contractor proposals and ensuring clarity on costs facilitates sound financial management, timely completion within budget, and overall financial success [2,17].

Consistency in funding and resource utilization stability supports cost-effective execution, while efficient conflict resolution mechanisms maintain stakeholder satisfaction and project momentum [7,18]. Adhering to desired quality standards and regulatory requirements through robust quality assurance mechanisms is essential, especially in sectors with strict regulations like water and wastewater [12]. Political stability and supportive legislative frameworks create a favorable environment for project success by providing reliable regulatory and compliance guidelines [11].

Challenges such as resistance to organizational change and navigating state procurement or municipal requirements can hinder project progression. Effective change management strategies, stakeholder engagement, and adaptability to regulatory protocols are necessary to overcome these challenges [14].

The following sections highlight the studies conducted in different sectors to examine the CSFs of DB projects.

2.1. Critical Success Factors in General Infrastructure

To define project success in DB projects, Lam et al. [19] have introduced a project success index tailored to the Hong Kong context. This index was assessed using project performance indicators, such as time, cost, quality, and functionality. Through the application of multiple regression analyses, it was identified that the project’s distinctive characteristics, adept project management practices, and the incorporation of contemporary management approaches were the key drivers of success in DB projects.

In a separate study, Lee [20] has conducted a qualitative analysis through interviews with Malaysian industry practitioners with hands-on DB project experience. The findings indicate that factors contributing to the success of DB projects were client capabilities (inclusive of the client’s ability to brief the project team and articulate clear goals, as well as a proper understanding of project scope), competency of the construction leader (capability and experience), competency of the consultant team (proficiency in design works and project management skills), organizational behavior (fostering a harmonious working environment and instilling confidence in team members), and an effective project management system (communication and organizational aspects).

Lee et al. [21] have investigated the CSFs associated with DB implementation in Malaysian public construction projects through a questionnaire survey. The findings highlighted the top five CSFs as the effective briefing of design by the client, prompt and authoritative decision-making by the construction leader, the establishment of mutual trust among project team members, seamless integration among team members, and the inclusion of project members possessing robust organizational, management, and leadership skills.

2.2. Critical Success Factors in the Building Sector

Chan [22] has used factor analysis on data collected from 53 participants involved in public-sector DB building projects, obtained through a questionnaire survey. The study identified six key project success factors: project team commitment, contractor competencies, risk and liability assessment, client competencies, end-users’ needs, and constraints imposed by end-users. Multiple regression analysis revealed that among these factors, “project team commitment,” “contractor competencies,” and “client competencies” emerged as the most critical factors for explaining the overall performance of DB building projects.

Adnan [23] has investigated the critical factors for DB projects in Malaysian public universities using interviews and a survey. The study identified several CSFs, including a clear understanding of project scope, a concise and thorough assessment of the contractor’s proposal, a comprehensive analysis of project costs, adherence to end-user requirements, ensuring the quality finish of the project, and achieving completion within the designated time frame and allocated budget. The study also emphasized the role of planning, monitoring, coordination, control, communication, and decision-making in project success.

Similarly, Dang and Le-Hoai [24] have identified six CSFs through correlation analysis, gathering data from both public and private sector DB building projects in Vietnam via a survey questionnaire. The six principal CSFs identified were rapid conflict resolution, effective comprehensive managerial actions encompassing planning, organizing, leading, and controlling, project participants’ satisfaction with the project’s financial returns, the presence of an experienced multidisciplinary project team, positive attitudes of competent project team members toward their work, and consistent availability of adequate funding throughout the project.

Lee [20] has interviewed Malaysian professionals (architects, engineers, and surveyors) and surveyed 111 professionals to understand the key drivers for DB adoption. The identified key DB drivers among these stakeholders consisted of factors such as maximizing the utilization of resources between project team members, sharing expertise (design and technical) with project team members, maintaining a well-organized project team structure, and emphasizing a high success rate. Notably, clients and contractors valued better project pricing and greater allocation of risks to contractors, while consultants emphasized design efficiency and a better track record.

2.3. Critical Success Factors in the Water and Wastewater Sector

Akrm Al-Juboori [25] has identified the five most important CSFs for water supply projects in Iraq through a questionnaire survey administered to 260 construction experts affiliated with the construction and education sectors. The five CSFs identified were a stable political environment, sustainable construction legislation and regulation, effective risk management practices, well-organized and committed project teams, and government decisions throughout the project life cycle.

The Water Design-Build Council (WDBC), in collaboration with the Civil and Environmental Engineering and Construction Department of the University of Nevada, Las Vegas (UNLV), conducted a survey in 2012 targeting policy officials, utility managers, and project staff members associated with the Water Environment Federation (WEF) and AWWA. The survey aimed to identify factors that hinder the success of DB projects within the water and wastewater sector. The survey results indicated that the top two internal challenges influencing the success of DB were identified as “unfamiliarity with the process by management or policy officials” and “resistance to change within management or policy officials”. Externally, the top two factors affecting the success of DB projects were determined to be “state procurement statutory requirements” and “municipal or agency procurement regulations” [26].

The summary of the CSFs for DB is given in

Table 1. List of critical success items identified for Design-Build projects.

CSI #	Critical Success Items	Lee et al. [21]	Dang [24]	Adnan [23]	Chan et al. [22]	Lam et al. [19]	Lee [20]	Shrestha et al. [26]	Akrm [25]
1	Client can effectively brief the design.	√		√	√	√
2	Client can effectively define the role of participants in the project.	√		√	√
3	Delegation of decision-making authorities from the client.	√	√	√	√	√
4	Project management skills of the client’s representative.	√		√	√	√
5	Mutual trust among the project team members.	√	√	√	√
6	Project team members with strong organizational, management, leadership, and controlling skills.	√	√			√	√
7	Project team members are well-integrated.	√				√			√
8	Project team members have good technical and planning skills.	√				√
9	Project team members have established good working relationships.	√				√
10	Clear flow of communication among the project participants.	√		√	√	√	√		√
11	Project team members demonstrate high satisfaction with their involvement in the project.	√
12	Design-Builder has a strong financial capability.	√	√	√					√
13	Design-Builder has a high commitment to achieving the project’s goals.	√	√	√		√			√
14	Design-Builder’s good combination of design expertise and building techniques.	√	√	√	√	√
15	Design-Builder’s strong construction management capability.	√	√	√	√	√
16	Design-Builder’s project team leader’s competence, experience, and delegated authority.	√	√			√
17	Owner’s quick response to Design-Builder’s requests and instructions.		√
18	Resolving conflicts quickly.		√	√	√		√
19	Effective monitoring and approval mechanisms for design changes.	√	√	√	√
20	Thorough understanding of project complexity.		√			√
21	Risk avoidance.								√
22	Input from the Design-Builder.			√	√	√
23	Maximize the use of resources between project team members.						√		√
24	Early Design-Builders’ involvement in the design stage.						√
25	Greater allocation of risks to Design-Builders.						√
26	Ability to bring change from traditional delivery methods within management, policy officials, and senior staff.							√
27	Familiarity with the DB process within management, policy officials, and senior staff.							√
28	Inclusion of the DB process in state procurement statutory requirements.							√	√
29	Inclusion of the DB process in municipal or agency procurement regulations.							√	√
30	Availability of qualified personnel for the DB project.							√

.

2.4. Gaps in the Literature

The existing literature on CSFs for DB projects reveals certain gaps that this study aims to address. While numerous studies have examined CSFs for general infrastructure, building, and public-sector projects, limited research focuses specifically on DB water and wastewater projects. Most existing studies generalize CSFs across multiple project types, failing to account for the unique characteristics and requirements of water and wastewater facilities. Additionally, previous research has identified several CSFs, but there is a lack of studies on the most critical items to ensure projects are completed under or on budget and schedule. While items like project team competence, leadership, and effective communication are acknowledged in general construction studies, it remains unclear how these items rank in importance for water and wastewater DB projects. In addition, the previous researchers have identified several factors that affect the general DB infrastructure projects, but these are not specific to the water and wastewater sectors. By addressing these gaps, this study provides a focused investigation into the specific CSIs and CSFs that influence DB water and wastewater project outcomes, thereby offering a sector-specific perspective that is currently lacking in the literature.

3. Methodology

The research aimed to fulfill its objectives in three phases. The first phase included an in-depth literature review of several articles pertaining to the CSIs and CSFs of general infrastructure’s DB methods, with specific infrastructures pertaining to buildings and water, and wastewater projects.

Secondly, based on the review, a questionnaire survey was developed that mainly included indicating the significance of the identified CSIs that impact the delivery methods’ cost and schedule performance. Before this survey was distributed to the respondents, it was reviewed by the local water and wastewater engineer working in the Las Vegas municipality. The list of the CSIs was not changed, but some items were reworded. This survey was distributed among water and wastewater utility owners, contractors, clients, consultants, and experts in the water and wastewater industry located in the US to rate the CSIs based on their experience.

The third step consisted of conducting a reliability analysis to validate the participants’ responses. Then, the next step was to calculate the Relative Importance Index (RII) of these factors based on their level of significance and rank them based on their RII. Finally, the top-ranked CSIs were discussed for DB water and wastewater projects, and CSFs related to budget and schedule will be identified using Principal Component Analysis (PCA). The recommendations are given as to how these factors can be focused to make DB water and wastewater projects schedule-efficient and cost-effective.

3.1. Inter-Rate Reliability Agreement Test for CSF Ranking

The inter-rater reliability agreement test is a reliability analysis employed to assess the degree of concordance among distinct respondents or raters. This test will be applied to evaluate the varied ratings furnished by respondents concerning the CSIs of DB projects in the water and wastewater sector. Intra-class correlation coefficient (ICC) is used in this type of test for evaluation of continuous measurements like Likert scale to assess agreement, which considers the systematic bias in measurements [27].

The ICC value can be calculated using Equation [28],

$$\mathrm{I}\mathrm{C}\mathrm{C}={\displaystyle \frac{\mathrm{V}\mathrm{a}\mathrm{r}\mathrm{i}\mathrm{a}\mathrm{n}\mathrm{c}\mathrm{e} \mathrm{o}\mathrm{f} \mathrm{d}\mathrm{i}\mathrm{f}\mathrm{f}\mathrm{e}\mathrm{r}\mathrm{e}\mathrm{n}\mathrm{t} \mathrm{r}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{n}\mathrm{g}\mathrm{s} \mathrm{a}\mathrm{m}\mathrm{o}\mathrm{n}\mathrm{g} \mathrm{t}\mathrm{h}\mathrm{e} \mathrm{s}\mathrm{u}\mathrm{b}\mathrm{j}\mathrm{e}\mathrm{c}\mathrm{t}\mathrm{s} \mathrm{i}\mathrm{n} \mathrm{t}\mathrm{h}\mathrm{e} \mathrm{p}\mathrm{o}\mathrm{p}\mathrm{u}\mathrm{l}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n} \mathrm{P}}{\mathrm{T}\mathrm{o}\mathrm{t}\mathrm{a}\mathrm{l} \mathrm{V}\mathrm{a}\mathrm{r}\mathrm{i}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}}}$$

(1)

A low ICC may indicate a low rater agreement, whereas a high ICC indicates high rater agreement. There are four common categories for ICC values:

• ICC value < 0.40: Level of Significance is poor;
• 0.40 < ICC value < 0.59: Level of Significance is fair;
• 0.60 < ICC value < 0.74: Level of Significance is good;
• 0.75 < ICC value < 1.00: Level of Significance is excellent.

3.2. Relative Importance Index (RII) Test

Relative Importance Index (RII) analysis has been used in the construction research industry to rank the significant items based on the level of significance determined for each. RII will be used in this study to determine the ranking of the CSIs of DB projects to achieve cost and schedule efficiency according to their relative significance. For RII analysis, the following five-point Likert scale of 1 to 5 has been adopted.

1 = Not Significant;

2 = Less Significant;

3 = Neutral;

4 = Significant;

5 = Highly Significant.

RII will be applied for each critical success factor using the given equation:

$$\mathrm{R}\mathrm{I}\mathrm{I}={\displaystyle \frac{\sum W}{\mathrm{A}\times \mathrm{N}}}$$

(2)

where

• W: Weight given to each factor by the respondents and ranges from 1 to 5 (where 1 is Not Significant and 5 is Highly Significant);
• A: Highest Weight (i.e., 5);
• N: Total Number of Respondents.

The RII value ranges from 0 to 1. It shows that the higher the value of RII, the more important the critical item is and vice versa.

3.3. Mann–Whitney U Test

The Mann–Whitney U test is a non-parametric statistical test used to determine whether there is a significant difference between two independent groups: critical and non-critical items. This test was selected to evaluate differences in medians, as it is appropriate when the dependent data are measured at the ordinal level. If the data are not normally distributed, then this test is used to measure the significant difference between critical and non-critical success items.

3.4. Principal Component Analysis

Principal Component Analysis (PCA) will be conducted to transform the correlated 27 CSIs into a smaller number of uncorrelated factors, called “budget and schedule-related CSFs”. Before conducting PCA, all the CSIs’ ratings were examined for potential outliers. The outlier plots show that there were no significant outliers in budget- and schedule-related CSI rating data. When the correlation matrices were analyzed for budget-related CSFs, CSI # 28, “Inclusion of DB process in state procurement statutory requirements,” and CSI # 29, “Inclusion of DB process in municipal or agency procurement regulations,” were highly correlated (correlation value = 0.90). The same is true for schedule-related CSFs; therefore, the latter CSI # 29 was removed while conducting PCA, as state procurement statutory requirements also cover municipal or agency procurement regulations. The remaining CSI correlation values were between −0.60 and +0.60, which do not show strong correlation.

4. Results

The survey questionnaire was distributed to 81 agencies. In total, 27 agencies, representing 33%, responded from a total of 14 states. The response rate for the survey is very good due to the difficulty in reaching the respondents and the questionnaire being long. The location of DB water and wastewater projects from various states across the US were California, Colorado, Florida, Georgia, Idaho, Maryland, Michigan, Minnesota, Nevada, New Mexico, Pennsylvania, Rhode Island, Virginia, and Washington. The survey also provides an overview of the geographic distribution of DB water and wastewater projects, encompassing responses from diverse states across the United States. The respondents were also asked about the type of water and wastewater projects they were involved in, with the majority being in conveyance projects (15), water treatment plans (12), and pumping stations (12). They also reported on the construction types, with most involved in New Construction (22), followed by rehabilitation (12), and expansion (9). Additionally, the respondents were also asked about their experience levels, revealing that 18 participants had more than 15 years of experience in DB water and wastewater projects.

4.1. Budget-Related CSIs

4.1.1. Consistency of Responses for Budget-Related Critical Success Items

The consistency of data for budget-related critical success items (CSIs) was evaluated using the ICC, as presented in

Table 2. ICC Analysis for CSIs for DB for completing the project under or on budget.

	Intraclass Correlation b	95% Confidence Interval
		Lower Bound	Upper Bound
Single Measures	0.164 a	0.100	0.277
Average Measures	0.841 c	0.748	0.912

^a The estimator remains consistent, regardless of the presence or absence of the interaction effect. ^b Intraclass correlation coefficients of Type A, employing an absolute agreement definition. ^c This estimation is calculated under the assumption of the absence of the interaction effect, as it is not estimable under alternative conditions.

. The results showed an ICC value of 0.164 for single measures and 0.841 for average measures, with a 95% confidence interval ranging from 0.748 to 0.912. These values indicate good consistency among the respondents’ ratings.

4.1.2. Ranking of Critical Success Items

To determine the top CSIs influencing budget performance, items with a median rating of 5 were selected. A median value of 5 indicates that these CSIs were ranked as “highly significant” by at least 50% of the participants. This approach ensures that only the most impactful and widely agreed-upon items are identified as CSIs.

Based on the RII and median values, seven budget-related CSIs (CSI # 5, 6, 8, 10, 14, 16, and 30) were identified as having significant impacts on completing DB water and wastewater projects within budget. They are (1) project team members have good technical and planning skills; (2) clear flow of communication among the project participants; (3) Design-Builder’s good combination of design expertise and building techniques; (4) mutual trust among the project team members; (5) Design-Builder’s project team leader’s competence, experience and delegated authority; (6) availability of qualified personnel with DB projects; and (7) project team members with strong organizational, management, leading and controlling skills.

Table 3. Ranking of CSIs based on RII for DB projects completed under or on budget.

Description of CSIs	CSI #	RII	Mean	Median	Rank
Project team members have good technical and planning skills.	8	0.91	4.56	5	1
Clear flow of communication among the project participants.	10	0.90	4.52	5	2
Design-Builder’s good combination of design expertise and building techniques.	14	0.90	4.52	5	2
Mutual trust among the project team members.	5	0.90	4.52	5	2
Design-Builder’s project team leader’s competence, experience, and delegated authority.	16	0.88	4.41	5	3
Availability of qualified personnel for DB project.	30	0.87	4.37	5	4
Project team members with strong organizational, management, leadership, and controlling skills.	6	0.87	4.37	5	4
Design-Builder’s strong construction management capability.	15	0.87	4.33	4	5
Owner’s quick response to Design-Builder’s requests and instructions.	17	0.87	4.33	4	5
Resolving conflicts quickly.	18	0.87	4.33	4	5
Design-Builder has a high commitment to achieving the project’s goals.	13	0.86	4.30	4	6
Project team members are well-integrated.	7	0.86	4.30	4	6
Thorough understanding of project complexity.	20	0.85	4.26	4	7
Project management skills of the client’s representative.	4	0.84	4.19	4	8
Project team members have established good working relationships.	9	0.84	4.19	4	8
Effective monitoring and approval mechanisms for design changes.	19	0.81	4.07	4	9
Early Design-Builders’ involvement in the design stage.	24	0.80	4.00	4	10
Client can effectively brief the design.	1	0.79	3.96	4	11
Input from the Design-Builder.	22	0.79	3.96	4	11
Familiarity with the DB process within management, policy officials, and senior staff.	27	0.77	3.85	4	12
Delegation of decision-making authority from the client.	3	0.76	3.81	4	13
Inclusion of the DB process in Municipal or agency procurement regulations.	29	0.75	3.74	4	14
Client can effectively define the role of participants in the project.	2	0.73	3.67	4	15
Maximize the use of resources between project team members.	23	0.73	3.67	4	15
Inclusion of the DB process in state procurement statutory requirements.	28	0.70	3.52	3	16
Project team members demonstrate high satisfaction with the involvement of the project.	11	0.70	3.48	4	17
Design-Builder has a strong financial capability.	12	0.70	3.48	4	17
Risk avoidance.	21	0.68	3.41	3	18
Greater allocation of risks to Design-Builders.	25	0.67	3.33	3	19
Ability to bring change from traditional delivery methods within management, policy officials, and senior staff.	26	0.64	3.22	3	20

presents all 30 factors with the RII values, mean, median, and their ranks.

The results of the Mann–Whitney U test indicate that there is a statistically significant difference between critical (CSI # 5, 6, 8, 10, 14, 16, and 30) and non-critical (the other 23) items for DB projects completed under or on budget, as shown in

Table 4. Result of Mann–Whitney U test for budget-related CSIs.

Factors	N	Mean	Median	Mean Rank	p Value
Critical	189	4.47	5	514.07	<0.001
Non-Critical	627	3.89	4	372.46

. The critical items have a higher mean (4.47) and mean rank (514.07) compared to the non-critical items (3.89 mean, 372.46 mean rank). The low p-value implies that this difference is unlikely to be due to chance, supporting the classification of items as “Critical” and “Non-Critical”.

4.1.3. Principal Component Analysis of Budget-Related Critical Success Factors (CSFs)

Principal component analysis was conducted using the Statistical Package for Social Science (SPSS Version 29.0.2.0) to determine the CSFs related to budget. During the PCA, varimax rotation was performed to reduce the 29 CSIs into a smaller number of factors. The test statistics of Bartlett’s test of sphericity were significant at the alpha level of 0.05, which shows the correlations of CSIs with factors that were significantly different from zero. For budget-related analysis, five factors were extracted that altogether accounted for 63.6% of the variance in responses.

Table 5. Result of Principal Component Analysis for budget-related CSIs.

CSI #	Critical Success Items	Factor Loading	% Variance	Total % Variance
Critical Success Factor (CSF) #1: Project Team Competencies
11	Project team members demonstrate high satisfaction with their involvement in the project.	0.92	28.3	28.3
5	Mutual trust among the project team members.	0.75
23	Maximize the use of resources between project team members.	0.72
12	Design-Builder has a strong financial capability.	0.71
13	Design-Builder has a high commitment to achieving the project’s goals.	0.56
26	Ability to bring change from traditional delivery methods within management, policy officials, and senior staff.	0.56
Critical Success Factor (CSF) # 2: Client’s Competencies
17	Early Design-Builders’ involvement in the design stage.	0.77	10.6	38.9
20	Familiarity with the DB process within management, policy officials, and senior staff.	0.69
21	Delegation of decision-making authorities from the client.	0.68
19	Input from the Design-Builder.	0.68
3	Design-Builder’s good combination of design expertise and building techniques.	0.58
Critical Success Factor (CSF) # 3: Client and Design-Builder’s Working Relationship
9	Owner’s quick response to Design-Builder’s requests and instructions.	0.80	9.0	47.9
8	Design-Builder’s strong construction management capability.	0.79
10	Resolving conflicts quickly.	0.58
16	Effective monitoring and approval mechanisms for design changes.	0.51
Critical Success Factor (CSF) # 4: Client’s Capacity
18	Client can effectively brief the design.	0.87	8.7	56.6
23	Client can effectively define the role of participants in the project.	0.82
25	Inclusion of the DB process in state procurement statutory requirements.	0.58
Critical Success Factor (CSF) # 5: Design-Builder’s Competencies
17	Project team members with strong organizational, management, leadership, and controlling skills.	0.80	7.0	63.6
5	Design-Builder’s project team leader’s competence, experience, and delegated authority.	0.64
28	Risk avoidance.	0.58

shows the five CSFs and CSIs that were included in each factor. The first three factors accounted for 28.3%, 10.6%, and 9.0%, respectively. All factor loadings were greater than 0.50.

The loading and interpretation of the CSFs are described below.

Project Team Competencies (CSF # 1): This factor consists of six CSIs that focus on project teamwork, satisfaction, trust, resource allocation, commitment, and attitudes. This factor emphasizes that the clients and Design-Builder’s members must have competencies to take on the challenge of DB projects and work together to successfully complete them within budget.

• Client’s Competencies (CSF # 2): This factor consists of five items that emphasize clients’ competencies related to the involvment of Design -Builder during the design phase and obtain their inputs, their decision-making process, their famlairty to the DB process, and their selection method of Design-Builders who have good design and construction expertise. This factor is important to complete DB water and wastewater projects on budget;
• Client and Design-Builder’s Working Relationship (CSF # 3): This factor consists of four items that highlight the qualities the client and Design-Builder must have to work as an effective team. The client should quickly respond to the Design-Builder’s requests for information (RFIs), monitor their design work, and approve it in a timely manner. The Design-Builder should also have management and conflict resolution skills to work effectively with the client. These attributes will help to complete DB water and wastewater projects within budget;
• Client’s Capacity (CSF # 4): In this factor, there are three CSIs related to the client’s capacity to successfully complete DB water and wastewater projects within budget. The client should make sure that the procurement policy clearly states how to procure DB projects. The client should also effectively communicate design scope and the Design-Builders’ roles during the DB project implementation phase;
• Design-Builder’s Competencies (CSF # 5): There are three items that were correlated to this factor. DB team members should possess strong organizational, management, leadership, and controlling skills. Their team leaders should be competent, have DB experience, and know how to avoid project risk. These attributes are important for the DB water and wastewater projects to be completed on budget.

These five CSFs represent important factors that the DB project owners and Design-Builders must focus on in order to complete their project on budget. These factors cover not only the Design-Builder’s team qualifications, skills, and knowledge to complete DB projects, but also the client’s characteristics, which play an important role in completing the project successfully. Without the client and Design-Builder’s combined efforts, DB projects cannot be successfully completed within budget.

4.2. Schedule Related CSFs

4.2.1. Consistency of Responses for Schedule-Related Critical Success Items

The consistency of data for schedule-related items was assessed using the ICC, as presented in

Table 6. ICC Analysis for CSIs for DB for completing the project under or on schedule.

	Intraclass Correlation b	95% Confidence Interval
		Lower Bound	Upper Bound
Single Measures	0.242 a	0.157	0.379
Average Measures	0.896 c	0.833	0.943

^a The estimator remains consistent, regardless of the presence or absence of the interaction effect. ^b Intraclass correlation coefficients of Type A, employing an absolute agreement definition. ^c This estimation is calculated under the assumption of the absence of the interaction effect, as it is not estimable under alternative conditions.

. The results showed an ICC value of 0.242 for single measures and 0.896 for average measures, with a 95% confidence interval ranging from 0.833 to 0.943, confirming strong agreement among respondents.

4.2.2. Ranking of Factors

Three critical success items (CSI # 10, 17, and 18) were identified as being significant for schedule performance, as they were ranked as highly significant (median = 5) by at least 50% of respondents. These items include (1) the owner’s quick response to Design-Builder’s requests and instructions, (2) resolving conflicts quickly, and (3) a clear flow of communication among the project participants.

Table 7. Ranking of CSIs based on RII for DB projects completed under or on schedule.

Description of CSIs	CSI #	RII	Mean	Median	Rank
Owner’s quick response to Design-Builder’s requests and instructions.	17	0.94	4.70	5	1
Resolving conflicts quickly.	18	0.94	4.70	5	1
Clear flow of communication among the project participants.	10	0.91	4.56	5	2
Project team members have good technical and planning skills.	8	0.88	4.41	4	3
Design-Builder’s strong construction management capability.	15	0.87	4.37	4	4
Project team members with strong organizational, management, leadership, and controlling skills.	6	0.87	4.37	4	4
Design-Builder’s project team leader’s competence, experience, and delegated authority.	16	0.87	4.33	4	5
Effective monitoring and approval mechanisms for design changes.	19	0.86	4.30	4	6
Availability of qualified personnel for DB project.	30	0.85	4.26	4	7
Mutual trust among the project team members.	5	0.85	4.26	4	7
Project team members are well-integrated.	7	0.85	4.26	4	7
Design-Builder’s good combination of design expertise and building techniques.	14	0.84	4.22	4	8
Delegation of decision-making authority from the client.	3	0.84	4.22	4	8
Project team members have established good working relationships.	9	0.84	4.22	4	8
Thorough understanding of project complexity.	20	0.83	4.15	4	9
Early Design-Builders’ involvement in the design stage.	24	0.81	4.07	4	10
Project management skills of the client’s representative.	4	0.81	4.07	4	10
Design-Builder has a high commitment to achieving the project’s goals.	13	0.80	4.00	4	11
Maximize the use of resources between project team members.	23	0.79	3.93	4	12
Input from the Design-Builder.	22	0.77	3.85	4	13
Familiarity with the DB process within management, policy officials, and senior staff.	27	0.70	3.52	3	14
Client can effectively brief the design	1	0.65	3.26	4	15
Project team members demonstrate high satisfaction with the involvement of the project.	11	0.65	3.26	3	15
Client can effectively define the role of participants in the project.	2	0.65	3.26	4	15
Risk avoidance.	21	0.65	3.26	3	15
Ability to bring change from traditional delivery methods within management, policy officials, and senior staff.	26	0.65	3.26	3	15
Inclusion of the DB process in state procurement statutory requirements.	28	0.63	3.15	3	16
Inclusion of the DB process in municipal or agency procurement regulations.	29	0.63	3.15	3	16
Design-Builder has a strong financial capability.	12	0.62	3.11	3	17
Greater allocation of risks to Design-Builders.	25	0.61	3.07	3	18

presents all the CSIs that are critical for completing the DB project on time, with the RII, mean, median, and their rankings.

The results of the Mann–Whitney U test indicate that there is a statistically significant difference between critical (CSI # 10, 17, and 18) and non-critical (the rest) items for DB projects completed under or on schedule, as shown in

Table 8. Result of Mann–Whitney U test for schedule-related CSIs.

Factors	N	Mean	Median	Mean Rank	p Value
Critical	81	4.65	5	577.15	<0.001
Non-Critical	729	3.84	4	386.43

. The critical items have a higher mean (4.65) and mean rank (577.15) compared to the non-critical items (3.84 mean and 386.43 mean rank). The low p-value implies that this difference is unlikely to be due to chance, supporting the classification of items as “Critical” and “Non-Critical”.

4.2.3. Principal Component Analysis of Schedule-Related Critical Success Factors (CSFs)

As for budget-related CSFs, the authors again performed PCA to determine the factors that are important to complete the DB projects within the scheduled duration. Similar tests were conducted as in the case of budget-related CSFs, and it was found that Bartlett’s test of sphericity was significant at an alpha level of 0.05. For schedule-related CSFs, a similar number of factors were extracted that altogether accounted for 63.7% of the variance in responses.

Table 9. Result of Principal Component Analysis for Schedule-related CSIs.

CSI #	Critical Success Items	Factor Loading	% Variance	Total % Variance
Critical Success Factor (CSF) #1: Project Team Competencies
12	Design-Builder has a strong financial capability.	0.83	26.5	26.5
11	Project team members demonstrate high satisfaction with their involvement in the project.	0.82
21	Risk avoidance.	0.82
7	Project team members are well-integrated.	0.65
13	Design-Builder has a high commitment to achieving the project’s goals.	0.60
5	Mutual trust among the project team members.	0.57
26	Ability to bring change from traditional delivery methods within management, policy officials, and senior staff.	0.55
2	Client can effectively define the role of participants in the project.	0.50
Critical Success Factor (CSF) # 2: Client’s Competencies
3	Delegation of decision-making authorities from the client.	0.84	13.2	39.7
22	Input from the Design-Builder.	0.80
23	Maximize the use of resources between project team members.	0.67
Critical Success Factor (CSF) # 3: Client and Design-Builder’s Competencies
16	Design-Builder’s project team leader’s competence, experience, and delegated authority.	0.89	11.1	50.8
17	Owner’s quick response to Design-Builder’s requests and instructions.	0.79
14	Design-Builder’s good combination of design expertise and building techniques.	0.70
25	Greater allocation of risks to Design-Builders.	0.62
Critical Success Factor (CSF) # 4: Client’s Capacity
4	Project management skills of the client’s representative.	0.84	6.8	57.6
6	Project team members with strong organizational, management, leadership, and controlling skills.	0.79
30	Availability of qualified personnel for DB project.	0.65
27	Familiarity with the DB process within management, policy officials, and senior staff.	0.65
8	Project team members have good technical and planning skills.	0.61
Critical Success Factor (CSF) # 5: Design-Builder’s Working Relationship
18	Resolving conflicts quickly.	0.88	6.1	63.7
19	Effective monitoring and approval mechanisms for design changes.	0.71

shows the five CSFs and CSIs that were included in each factor. The first three factors accounted for 26.5%, 13.2%, and 11.1%, respectively. All the items’ loadings were greater than 0.50.

The PCA shows that the majority of the items included in these five factors are similar to the budget-related analysis. Four factors are similar to the budget-related factors; however, a new factor was constructed. The five factors and the difference in items included in each factor are explained below.

• Project Team Competencies (CSF # 1): In this factor, there are a total of 8 items that have a factor loading value of 0.50 and higher. Compared with the items included in this factor for budget-related analysis, there are five identical items included. They are CSI # 5, 11, 12, 13, and 26. Three more items (CSI # 2, 7, and 21) were included. The project team’s competence should include team members’ attitude of risk avoidance and a cohesive environment where the entire team works as a group. Apart from these competencies, the clients should define the role of participants in the project. However, these three items are more critical to complete the DB project on time than to complete the project on budget;
• Client’s Competencies (CSF # 2): There are a total of three items included in this factor. Out of these three, two are similar to the items included in the budget-related factor. The third item included in this factor is “to maximize the use of resources between project team members”, which is critical to completing the project on time. If the client does not distribute their resources properly, then it will have an adverse effect on project completion;
• Design-Builder’s Competencies (CSF # 3): This factor was ranked fifth in the budget-related factors; however, for the schedule-related factors, it is placed third. This factor accounted for 11.1% of the variance of the responses. CSI # 16 was the only common item in both scenarios. CSI # 14, 17, and 25 were included in this factor, which were different from the budget-related analysis. One of the competencies of Design-Builder is to check whether they have a good combination of design and building techniques, so that the DB project can be completed on time. Also, the Design-Builder should be able to take more risks during the DB project, and they should be able to effectively communicate with the client to collect quick responses for their RFIs;
• Team Members’ Capacity (CSF # 4): It is a new factor compared to the budget-related factor analysis. There are five CSIs included in this factor, and these items are related to the team members’ capacity for handling DB projects. These items were not included in the case of the budget-related factor. Therefore, a new name was provided. The team members’ capacity includes client and team’s project management skills, availability of qualified people, client familiarity with the DB process, and team members’ technical and planning skills. All of these project team members’ characteristics contribute to completing the DB project on time;
• Client’s and Design-Builder’s Working Relationship (CSF # 5): This factor has two items, and both of these items are also included in a budget-related factor. The items are to resolve conflicts quickly and ensure effective monitoring and approval of design changes. These two attributes are very important for DB projects to be completed on time.

5. Discussion

The findings from this study on the CSIs and CSFs for DB water and wastewater projects completed under or on budget and schedule were compared to previous studies to evaluate similarities and differences in the items’ rankings. The comparison provides insights into evolving priorities and practices in DB water and wastewater project management and other DB projects.

5.1. Budget-Related CSIs Ranking

The results indicate that CSI # 8 ranked the highest in this study, aligning with its significance in ensuring cost efficiency and budget management. This differs significantly from previous studies, such as Lam et al. [19], where it was ranked 5th, and Lee et al. [21], where it was ranked 7th. This item is related to the project team members’ technical and planning skills. Water and wastewater projects differ from other infrastructure projects in terms of technical details. The variations in ranking across studies reflect differences in emphasis on technical skills based on project context and regional practices. In DB water and wastewater projects, the team members should have knowledge about the design components, because these projects involve designing and installing wastewater treatment equipment, which requires high levels of technical knowledge. Therefore, this item is highly ranked for water and wastewater projects compared to other general infrastructure projects. CSI # 5, 10, and 14 were ranked 2nd in this study. CSI # 5, which is mutual trust among the project team members, is highly ranked by Chan et al. [22] and Lam et al. [19], showing that it is recognized as an important factor in DB project success irrespective of project types. CSI # 10 is ranked 2nd by this study. This item is related to the communication between the project participants. As this study is related to water and wastewater projects, there should be high levels of communication with the client, designer, and builder to make sure that the design is performed with value engineering and constructability. This will help to reduce the cost overrun of the project. CSI # 14 is also ranked 2nd by this study. Other studies did not rank this item in the top five. CSE # 14 is related to the Design-Builder’s knowledge about design and construction capability. Because of this, the Design-Builder should have this qualification to prepare the design so that there are fewer change orders and the cost overrun can be controlled.

This study ranked CSI # 16 as 3rd to complete the DB water and wastewater project within budget, showing its role in mitigating the financial impact of change orders. This item is related to the Design-Builder leader’s competence, experience, and authority. Lam et al. [19] ranked it 2nd, which is consistent with its importance in managing changes effectively in cost control programs. Other studies have not identified this item as critical due to project types and location differences. CSI # 6 and # 30 were ranked 4th in this study, emphasizing the need for qualified personnel and team members having strong organization, management, and leadership skills to control the budget overrun. This aligns with its ranking in Lam et al. [19] (1st) and Lee et al. [21] (4th), further validating its critical role in project cost management.

Table 10. Comparison of the ranking of CSIs for DB projects completed under or on budget with the ranking of CSIs for previous studies.

CSIs #	Ranking
	This Study	Chan [22]	Lam [19]	Lee [20]	Lee [21]
8	1	NA	5	NA	7
10	2	9	NA	NA	13
14	2	8	NA	7	NA
5	2	1	4	NA	NA
16	3	NA	2	NA	NA
30	4	NA	NA	NA	NA
6	4	NA	1	NA	4

shows the comparison of the ranking of CSFs for DB water and wastewater projects completed under or on budget with the ranking of CSIs for previous studies.

Five of the seven CSIs identified as related to DB water and wastewater projects completed on budget are related to the team members’ skills and knowledge. CSIs # 5, 6, 8, and 10 are related to the project team’s knowledge, communication, and technical skills. These attributes are critical for DB projects to be completed on budget. Without mutual trust and clear communication, it will be difficult to control the cost overruns of the project. Most of the DB water and wastewater projects are complex and large, so the Design-Builder team members should have clear lines of communication, and there should be mutual trust developed between them to solve problems so that the project can be completed within budget.

In addition to this, the project team members should have strong management and technical skills to make the DB project successful. CSI # 14 and # 16 are related to the Design-Builder team’s design and construction experience and the team leader’s competencies. To complete the DB on budget, the Design-Builder should have vast experience in estimating the project accurately. Because in DB projects, the design has not been completed at the time of bidding; therefore, the Design-Builder must design the project and come up with an accurate estimate of the project. If the project cannot be estimated accurately, the Design-Builder cannot complete the project on budget, so team members’ experience and skills are the most important factor in making the DB water and wastewater projects successful. Critical success item # 30 is about the availability of qualified personnel who have experience in DB projects. This is very important as the team members who do not have DB project experience cannot contribute effectively to control the cost, because these team members do not know how change orders in the DB projects work.

5.2. Budget-Related Critical Success Factors (CSFs)

The PCA showed that 22 CSIs can be combined into five critical success factors that are important for completing DB water and wastewater projects within budget. These five factors can be named as project team competencies, client’s competencies, client and Design-Builder’s working relationship, client’s capacity, and Design-Builder’s competencies. In DB projects, the attributes needed to make the project successful will generally be related to the attributes of the client or Design-Builder, or the entire team. All six CSIs in project team competencies were related to items that were either the Design-Builder team’s or the client team’s commitments, skills, and attitudes towards DB processes. To complete the DB water and wastewater project on budget, the design builder and the client must work together with high levels of trust, commitment, and open minds. The client’s competencies highlighted five major items that must be in the client’s work culture. The client should be familiar with the DB process, delegate their authority to the appropriate people, seek inputs from the Design-Builder by involving them early in the design stage, and select a Design-Builder who has experience in both design and construction. The client and Design-Builder working relationship factor highlights the attributes that are needed on both sides to complete the DB project on budget. This factor highlights the need to resolve the conflicts quickly and create an effective design approval mechanism that responds to the Design-Builder’s design-change request quickly. It also highlights Design-Builder’s construction management capacity to work with the client in the DB delivery process.

When comparing this study’s findings of budget-related factors with previous studies, the main difference is that none of the previous studies have identified the CSIs and CSFs based on the DB projects’ cost and schedule efficiencies. Also, none of the studies focus on DB water and wastewater projects. Chan et al. [22], Lam et al. [19], and Lee et al. [21] have created factors based on general DB projects because the sample of the respondents was selected from individuals who have experience in DB projects, irrespective of the type. Therefore, to have differences in findings is reasonable. Chan et al. [22] have found six factors related to DB project success, and among them, three factors were similar to this study’s findings. They are project team commitment, contractor’s competencies, and client’s competencies. This study has found three factors similar to these as project team competencies, Design-Builder’s competencies, and the client’s competencies. However, the CSIs included in these factors are somewhat different due to the nature of the projects and the geographical location. Lam et al. [19] have found 12 factors related to DB project success. However, the three factors stated above are similar, and one other factor is similar to this study’s finding: the working relationship among project team members. Lee et al. [21] have found three factors that are different from this study’s findings because Lee et al.’s [21] study was more focused on finding factors related to companies and their capacity to handle DB projects rather than focusing on clients and Design-Builders’ attributes. They found that the company’s cost- and industry-related forces have a high impact on making DB projects successful.

5.3. Schedule-Related CSIs Ranking

Table 11. Comparison of the ranking of CSIs for DB projects completed under or on schedule with the ranking of CSFs for previous studies.

CSIs #	Ranking
	This Study	Chan et al. [22]	Lam et al. [19]	Lee et al. [20]	Dang [24]
17	1	NA	NA	NA	2
18	1	3	NA	NA	3
10	2	8	NA	7	NA

shows the comparison of the ranking of CSIs for DB projects completed under or on schedule with the ranking of CSIs for previous studies. The RII analysis shows that CSI # 17, “Owner’s quick response to Design-Builder’s requests and instructions,” and CSI # 18, “Resolving conflicts quickly,” were ranked first. This reinforces that it is necessary for the client to be responsive to Design-Builder’s RFIs, as well as resolve disputes quickly, to complete the project on time. This study’s findings highlight the client’s critical role in maintaining project timelines through timely decision-making and approvals. This aligns with Dang and Le-Hoai [24], where this item was ranked 2nd, reinforcing its significance in schedule adherence. The absence of this item in other studies indicates that it may have gained prominence in recent years or in specific project contexts where rapid decision-making is essential. Chan et al. [22] and Dang and Le-Hoai [24] ranked CSI # 18 3rd, confirming its consistent recognition as a vital element in preventing schedule disruptions. These findings emphasize the importance of minimizing delays caused by disputes between the client and the Design-Builder. CSI # 10 “Clear flow of communication among the project participants” was ranked 2nd in this study, underscoring its importance in ensuring seamless collaboration and coordination, which are essential for maintaining project timelines. However, Chan et al. [22] ranked this factor 8th, and Lee et al. [20] ranked it 7th, indicating some variation in its perceived importance across different studies. As stated above, in DB water and wastewater projects, the technical knowledge about water and wastewater treatment equipment is necessary for the client and the Design-Builder. Without this knowledge, disagreements between them can delay project completion. This is not the case in other general infrastructure projects. In addition, this difference may reflect variations in project complexity or regional management practices. All these critical items are related to the communication skills and processes that will expedite the DB project’s progress. If the owner and Design-Builder do not have a clear line of communication and are not on the same page, then it will be difficult to complete the project on time.

5.4. Schedule-Related Critical Success Factors

The PCA results show that there are five factors in which most of the items (22 out of 30) are included. Those five factors are similar to budget-related ones. However, some of the items included are different because the respondents’ focus is to complete the project on time rather than on budget. Compared to the budget-related factors, out of 22 items included in schedule-related factors, 18 are the same items. This shows that some of the items are critical, whether the DB project needs to be completed within budget or on time. The PCA results also show that the items included in most schedule-related factors are similar to the budget-related ones. The reasons for the variations on items included are also stated below.

• Project Team Competencies (CSF # 1): In this factor, there are five items that are also included in the budget-related analysis. The three extra items included in this factor are: (1) risk avoidance, (2) project team members are well-integrated, and (3) the client can effectively define the role of participants in the project. The respondents agreed that, to complete the project on time, project team members should avoid risks and work as a team. The client should clearly communicate with each team member their roles, responsibilities, and authorities. This will assist the team in achieving the DB project goals;
• Client’s Competencies (CSF # 2): In this factor, there is one more item included compared to the budget-related factor. It is to maximize the use of resources among project team members. It is important for the client to distribute project resources based on the needs of the team members. If the required resources are provided to each team member, it will help to complete the project on time;
• Design-Builder’s Competencies (CSF # 3): Out of four items included in this factor, one item was also included in the budget-related analysis. The other three items included in the schedule-related factor are related to the Design-Builder’s capacity to take more risks, their expertise in the design and construction of DB projects, and how their RFIs are handled by the client. These items highlight how important it is for Design-Builder to have past experience in handling DB projects, so that they can complete the project on time;
• Team Members’ Capacity (CSF # 4): This is a new factor that was not constructed in budget-related analysis. The items included in this factor are the team members’ knowledge, skills, qualifications, and experience related to the DB process. This study has found that this factor is critical in completing the project on time. Without these attributes, it will be difficult for the team to handle complex DB projects and may cause delays;
• Client’s and Design-Builder’s Working Relationship (CSF # 5): The items included in this factor are similar to those of the budget-related analysis. This shows that, to complete the project on time, the client and Design-Builder should have those attributes.

6. Limitations

The study is constrained by certain limitations. The relatively small sample size of 27 responses limits the generalizability of the findings. The authors tried to achieve high response rates; however, due to water and wastewater respondents’ busy schedules and the long questionnaire, most of the respondents did not complete the survey. Even though the sample size is small, the authors were able to find significant critical success items and factors that can be valuable for water and wastewater project managers to consider and make their future DB projects successful. As the study’s sample size is small and the respondents were geographically located in the US, the readers should take caution in generalizing its results to projects in other regions. The project managers should consider these critical success items and factors during the implementation of DB water and wastewater projects, but should not solely rely on them to make their DB water and wastewater projects successful.

Additionally, critical factors such as Commissioning and Start-Up were not included due to their limited presence in the existing literature and survey responses. These factors were identified only after sending the questionnaire to the respondents. Some respondents mentioned them in the list of CSIs and also ranked them. They are particularly important for water and wastewater projects, as they ensure the proper operation and maintenance of facilities after construction. However, for some of the CSIs, e.g., CSI # 20, “thorough understanding of project complexity,” CSI # 24, “early Design-Builders’ involvement in the design stage,” and CSI # 22, “input from the Design-Builder” are somewhat related to commissioning and startup, because the Design-Builder should bring up issues related to startup during the design phase.

Future research should address these limitations by including a larger and more balanced dataset, exploring alternative ranking methods such as the Delphi Approach, so that previously overlooked factors like Commissioning and Start-Up will be included in the CSI list. Moreover, continuously updating the list of CSIs based on newer literature and stakeholder experiences is essential to address the evolving challenges in the water and wastewater sectors. Including more CSIs will also help to find more CSFs related to budget and schedule. These efforts will enhance the robustness of project management practices and contribute to the successful execution of DB water and wastewater projects.

7. Conclusions

This research has ranked CSIs to complete DB water and wastewater projects under or on budget and schedule. In addition to this, PCA was conducted to determine the CSFs that are critical for the successful completion of DB projects. To achieve this, an extensive literature review was conducted to examine project delivery methods, their classifications, essential CSIs for project success, and statistical methodologies for ranking and factor development purposes. Based on this, a questionnaire survey was developed and distributed among relevant stakeholders, including utility owners, contractors, and designers across various states in the United States.

The research gathered 27 survey responses from these stakeholders, providing diverse perspectives on DB water and wastewater projects. The survey results were analyzed using Reliability Analysis (ICC Analysis) in R Studio Version 4.3.3, which showed excellent agreement among the respondents, validating the reliability of the rankings. The RII was calculated for each CSI, and they were ranked accordingly, which identified the important items affecting the successful completion of DB water and wastewater projects under or on budget and schedule. In addition, PCA in SPSS was conducted to construct the factors that are relevant to complete DB projects within budget and on schedule.

The significant CSIs identified for DB water and wastewater projects include project team members having good technical and planning skills; mutual trust among the project team members; clear flow of communication among the project participants; Design-Builder’s good combination of design expertise and building techniques; Design-Builder’s project team leader’s competence, experience, and delegated authority; resolving conflicts quickly; and the owner’s quick response to Design-Builder’s requests and instructions. The CSIs identified that on-budget project completion was related to team members’ experience, skills, and knowledge about the DB process. The CSIs related to the schedule all pertained to how fast the owner and Design-Builder can settle the conflict, as well as their clear line of communication. These factors represent the foundational elements that stakeholders should prioritize to achieve project success.

There are five budget- and schedule-related CSFs identified from the PCA. Four factors were similar for both cases, and the majority of the items loaded in these factors were similar. The four factors developed from this analysis were (1) project team competencies, (2) client’s competencies, (3) Design-Builder’s competencies, and (4) client and Design-Builder’s working relationship. All these factors and items included in these factors are very important in completing DB water and wastewater projects within budget and on schedule. In the analysis of budget-related factors, items related to the client’s capacity to handle DB projects were constructed, which cover the client’s ability to communicate design, their roles and responsibilities, and their familiarity with state procurement rules. These are very important items for clients before they start using the DB delivery method to design and construct water and wastewater projects, and expect to complete the project within budget. In the case of schedule-related analysis, a new factor was developed that pertained to team members’ capacity. This factor was included with items that were related to the team members’ skills and knowledge about the DB process and the strong management and leadership attributes required to complete the project on time. The findings of the factors related to budget and schedule were somewhat different due to the team’s focus on completing the project on budget or schedule. The items included in these factors should be different when the project team members’ goals are different.

The primary contribution of this study is to determine the CSI separately to complete the DB water and wastewater projects within budget and on time. Previous studies had determined critical success items for general DB projects only. This is the first attempt to determine the CSIs of DB projects based on the types of projects (in this case, water and wastewater projects). Another contribution of this study is that it found critical success factors separately for the budget- and schedule-related performances of DB water and wastewater projects. None of the previous studies had performed this type of analysis. The findings of this study show that the items included in each of the factors for budget-related and schedule-related are different. The practitioners should consider different critical factors and items when completing the DB projects on budget or on schedule. The stakeholders of DB projects should focus on these identified CSIs and CSFs to complete their project on budget and on time. While selecting the Design-Builder, the client should focus on their competencies and capacities. Similarly, for the Design-Builder, before bidding for any DB project, they should find out the client’s competencies and capacities. While putting together the DB team, both clients and Design-Builders should make sure that their team members have those attributes found under project team competencies and capacity factors. Since DB projects are completed within budget and schedule due to the combined effort of both parties, the working relationship between these entities is critical. This type of analysis for budget- and schedule-related factors had not been conducted previously. Therefore, this study is unique in terms of its objectives and findings.

The study’s findings in the water and wastewater industry are expected to provide a better insight into the underlying components of project success to the water and wastewater utility owners, contractors, design consultants, and experts. Based on the availability of resources and the CSIs and CSFs obtained from the study, owners can make informed decisions to choose the appropriate delivery method for their project’s success.

The authors would also like to recommend conducting further studies that focus on how to build water infrastructure projects successfully, considering the reallocation of water resources from rural to urban areas. It is not only important that the water infrastructure projects be built within budget and schedule, but it is also important to select water infrastructure projects that reallocate water from irrigation to other valuable uses. The study recommends policy guidelines and regulatory measures that would limit the reallocation of water from irrigation to other sectors due to rising urban water demand [29]. This study can form the basis of investigating this topic for future studies.