Exploring Causes of Waste Relating to the Role of Project Managers in Highway Projects in Pakistan ^†

Abstract

The construction industry is struggling to resolve the issue of the enormous quantity of waste produced during construction processes, which impacts the performance and sustainability of projects. Causes of waste generation have been studied by researchers to formulate waste minimization strategies for these projects. The research on waste in highway infrastructure projects and waste causes specific to the roles and competencies of project team members is inadequate. This quantitative study addresses this gap by evaluating the influence of project managers (PMs) in minimizing CW through a structured questionnaire survey administered to 300 professionals, yielding 129 valid responses (43% response rate). The results indicate that 8.5% of construction materials are wasted in highway projects. Among four key project stakeholders (PM, quantity surveyor, designer, and client), PMs were rated as having the most significant impact on waste minimization (mean Likert score: 4.5/5). Using the Relative Importance Index (RII), the study identified the top five waste causes linked to PM competencies: faulty work requiring the work to be carried out again (RII = 0.742), wrong construction methods (0.734), lack of awareness (0.731), poor supervision (0.721), and poor material planning (0.706). A waste minimization framework is proposed, linking each of these causes to specific PM competencies and actionable strategies. These findings provide empirical support for targeting PM training and resource planning to reduce material waste in highway construction projects.

1. Introduction

The role of the project manager (PM) is considered the most critical to the success of any construction project. PMs are responsible for a wide range of duties and tasks, all leading towards the success of a project, which means project completion within the prescribed time and budget and to an adequate quality [1,2]. PMs also share their responsibility towards financial and environmental sustainability of construction projects with other stakeholders, which requires them to pay increased attention to waste minimization [3]. Waste generation in construction projects, particularly in highway infrastructure projects, is a significant issue with serious sustainability implications. Highway infrastructure projects are susceptible to unique challenges relating to logistics, management, and performance [4]. These projects consume huge quantities of materials, and a small percentage of waste can adversely affect the performance and sustainability of projects [5,6]. Time and cost overrun in construction projects are also correlated with waste generation [7].

Many waste management studies have quantified waste percentages of various materials used in construction projects to signify the impact of waste on project performance [8,9]. Moreover, studies have also endeavored to identify waste causative factors in construction projects. These causative factors assist in understanding and formulating waste-minimizing strategies. Most of the studies on causative factors of waste have evaluated inter alia human resources/workers/people as one of the most important factors impacting waste generation, without focusing on specific roles of important project team members in waste management [10]. A few studies on the roles of project managers, designers, quantity surveyors, and workers have been conducted; however, they are primarily focused on the attitudes and behavior of stakeholders towards waste generation in construction projects and do not discuss individual or combined professional roles of project team members [11,12]. In the context of waste management in highway projects, the roles of project team members have not been studied adequately [13].

There is a need to study the roles/responsibilities of construction project team members in waste reduction by relating relevant waste causative factors with the roles/responsibilities of team members. In this regard, examining the role of the PM vis-à-vis waste causes is of utmost importance, especially in highway projects.

1.1. Construction Waste (CW)

Construction waste (CW) has been described as the fraction of materials consumed at a work site out of the total materials delivered [14,15]. Another definition of CW refers to material losses and unnecessary work that result in additional costs without adding value [16]. Waste reduction or minimization is regarded as the most cost-effective strategy within the broader waste prevention framework [17,18]. However, research specifically focused on waste prevention based on causative factors is limited [19]. Furthermore, most existing studies on waste generation are either general or focused on building projects, with only a few addressing highway or infrastructure projects [19,20].

In the context of highway projects, a recent study on the wastage of Aggregate Base Course (ABC) material proposed waste reduction measures corresponding to the causes of material wastage [21]. A recent study conducted in Pakistan proposed strategies for waste reduction in road projects by evaluating waste factors [22]. Another study evaluated causative factors relating to the responsibilities of quantity surveyors in waste reduction in highway projects in the Pakistani context [13].

1.2. Roles of PMs

The PM is considered the most important member of the construction project team and endeavors to use all available project resources efficiently and effectively for the success of the project [2,23]. PMs have also been termed Change Agents as they address anomalies and introduceimproved processes and technologies [3,23]. The key roles/competences of PMs have been shortlisted from the literature for the purpose of this study (adopted from [1]) (see Figure 1).

1.3. Causes of CW Related to Roles of PM

Contemporary research includes many studies that identify and evaluate a host of waste generation causes in construction projects, which are subsequently grouped into waste causative factors after evaluation [2,3,4,5]. Most of the studies are generic and focused on waste produced in building projects, while a few examine waste causes in highway and infrastructure projects [6,7]. A review study indicated that the most repeated waste causes were frequent design changes, storage, mistakes by workers, planning issues, leftover materials on site, ordering the wrong materials, and weather [2]. Waste causes relating to the role of project team members have not been studied sufficiently [8,9]. Most of the waste management studies on human resources/workers employed on construction projects have been focused on their attitudes and behavior towards waste generation in construction projects and have ignored their professional roles/duties/competencies [11,12]. In this study, fifteen waste causes relating to the competencies of construction project members have been identified.

Table 1. CW causes related to PMs’ key roles.

ID	CW Causes	Source	PMs’ Key Roles/Competencies (Figure 1)
W1	Faulty work requiring the work to be carried out again	[10,11]	Quality Management
W2	Storage inadequacies	[12,13]	Resource Management
W3	No waste management plan	[3,10]	Cost Management/HSE
W4	Poor supervision of work	[24,25]	Quality Management
W5	Poor material planning	[14,26,27]	Resource Management
W6	Poor coordination	[3,13]	Team Management
W7	Wrong construction methods	[3,10]	Knowledge of Construction
W8	Equipment-related issues	[15,16]	Resource Management
W9	Gaps between different processes	[10,13]	Time Management
W10	Poor working conditions	[3,13]	HSE
W11	Inadequate planning time	[13,17,26]	Time Management
W12	Attitude and behavior issues	[8,18,19]	Team Management
W13	Lack of awareness	[3,10]	Communication
W14	Pace of work	[3,10]	Time Management
W15	Bulk procurement in advance	[25,26]	Resource management

shows CW causes associated with the competencies of PMs mentioned in the preceding paragraph.

1.4. Quantification of CW

The significance of construction material in a project can be easily evaluated from its overall share in the project cost, which is generally estimated to be 60–70% of the total project cost [20,21]. Studies have reported that almost 10% of the construction materials delivered are wasted [23]. In highway construction projects, wastage is even greater due to their distinct characteristics [7,28]. Generally waste quantification requires elaborate measurements and observations over a project’s duration; however, researchers have also quantified wastage of materials based on opinions/perspectives of experts and professionals [16].

1.5. Study Rationale and Objectives

The individual roles of project team members in reducing waste have not been studied adequately. Although most of the studies on causative factors have included human resources/workers/people as one of the factors, the important, unique, and varied roles performed by project team members have been ignored in most of these studies. The literature includes a host of studies on behavior and attitudes towards waste minimization; however, these studies do not also examine professional roles/duties of project team members [11,12].

The aims of this study are as follows:

• To compare the roles of important team members in highway projects (PM, quantity surveyor, designer, and client) in waste minimization to ascertain who plays the most critical role in waste minimization.
• To identify and evaluate waste-causing factors relating to the roles/competences of highway construction project managers.
• To recommend a conceptual framework for minimizing CW.

2. Research Methodology

This quantitative study was carried out in multiple stages through a questionnaire survey. The research methodology flow chart is shown in Figure 2. Many similar studies have also used a questionnaire survey to evaluate the causes of waste generation [3]. The questionnaire survey was structured in four sections (the Questionnaire is presented in Appendix A 

Table A1. Questionnaire Survey.

ID	Questions	Responses (Score) 1 Very Low, 2 Low, 3 Neutral, 4 High, 5 Very High
W1	What is impact of faulty work (requiring rework) on waste generation?	1	2	3	4	5
W2	What is impact of Storage inadequacies on waste generation?	1	2	3	4	5
W3	What is impact of No Waste Management Plan on waste generation?	1	2	3	4	5
W4	What is impact of Poor supervision of work on waste generation?	1	2	3	4	5
W5	What is impact of Poor material planning on waste generation?	1	2	3	4	5
W6	What is impact of Poor coordination on waste generation?	1	2	3	4	5
W7	What is impact of Wrong Construction methods on waste generation?	1	2	3	4	5
W8	What is impact of Equipment related issues on waste generation?	1	2	3	4	5
W9	What is impact of Halts between different processes on waste generation?	1	2	3	4	5
W10	What is impact of Poor Working Conditions on waste generation?	1	2	3	4	5
W11	What is impact of Less Planning Time on waste generation?	1	2	3	4	5
W12	What is impact of Attitude and Behavior issues on waste generation?	1	2	3	4	5
W13	What is impact of Lack of Awareness on waste generation?	1	2	3	4	5
W14	What is impact of Pace of Work on waste generation?	1	2	3	4	5
W15	What is impact of Bulk Procurement in Advance on waste generation?	1	2	3	4	5

). In the first section, the profile of respondents was acquired. In the second section, respondents were asked to report waste percentage ranges as per their perception. The third section inquired about the impact of important team members on waste minimization in highway projects, using the mean values of Likert Scale responses, to ascertain which team member is deemed most important for waste reduction. In the last section, the respondents were asked about the impact of waste causes relating to the roles/competences of PMs. The Likert Scale data was statistically analyzed using the Relative Importance Index (RII) for the ranking of each cause (See Equation (1), adapted from [13,14]):

RII = ƩW/(A × N)

(1)

where “W” is weightage of factors, “A” is largest value of weightage, and “N” is respondents.

3. Respondents’ Profile

The questionnaire survey (created using Google Forms) was delivered to 300 highway construction professionals working in Pakistan. A total of 129 completed forms were accepted for the analysis for this study. The response rate was 43%. This sample size is adequate for this exploratory study, as several similar studies on CW management have been conducted with sample sizes ranging between 110 and 140 [13,25,29]. In total, 42% of respondents had 21 years of experience or more, while those with 6–10, 11–15, and 16–20 years of experience accounted for 16%, 14%, 14%, and 12% of respondents, respectively. Most of the respondents were BE-qualified Civil Engineers (51%), followed by MS-qualified Civil Engineering professionals (30%), and the remaining respondents (placed in the miscellaneous category) were PHD, B Tech, and DAE holders. The nature of the experience of respondents was diversified, including clients (20%), contractors (51%), and consultants (20%). The Profile of the respondents is shown in Figure 3.

4. Results

4.1. Quantification of CW Percentages

The analysis of data obtained in Section 2 of the questionnaire showed that the largest percentage of respondents (35%) opined that the waste percentage was within the wastage range of 6–10%, while 27% of respondents though that the waste percentage range was between 3 and 5%, and 22% of respondents reported a waste percentage range of 11–15%. The waste percentage ranges as per the perceptions of respondents are shown in Figure 4. The mean value of the data was calculated to be 8.5%, whereas the median range of the data was computed to be 6–10%. These results confirm that a substantial quantity of construction materials is wasted.

4.2. Responsibility of Team Members

In the second part of the questionnaire based on the Likert Scale, the respondents were asked about the degree of impact important team members had on waste reduction. The important team members included designers, quantity surveyors, PMs, and clients. The five-point Likert options included Very High (5), High (4), Moderate (3), Low (2), and Very Low (1). Figure 5 shows the impact of important team members on waste minimization. The mean impact of PMs (4.5) was found to be the highest, followed by quantity surveyors (4.2), designers (3.8), and clients (3.2). Therefore, PMs were deemed the most impactful team members for waste minimization as per the perceptions of the respondents.

4.3. Most Significant Causes Relating to Role of PM

In this section, respondents were asked about the impact of each waste cause related to the roles of PMs on waste generation on the same Likert Scale used in the preceding section. Reliability analysis of the data was carried out using the statistical package SPSS^® version 20. Cronbach’s Alpha (α) was computed to be 0.872, which means that the reliability of data was good, i.e., 8 ≥ α ≥ 9 [30]. The overall ranking of CW causes was calculated using the RII method. The RII score has been used in many studies for the ranking of construction waste causes [3,14]. The top five causes of wastage related to PM competencies in highway projects according to this study were faulty work requiring the work to be carried out again (W1), wrong construction methods (W7), lack of awareness (W13), poor supervision of work (W4), and poor material planning (W5).

Table 2. Ranking of CW causes as per RII.

ID	1	2	3	4	5	RII	Ranking
W1	0	12	41	46	28	0.742	1
W7	0	8	44	57	18	0.734	2
W13	1	15	33	56	22	0.731	3
W4	5	9	34	62	17	0.721	4
W5	3	16	35	57	16	0.706	5
W6	2	14	50	42	19	0.698	6
W2	1	19	42	49	16	0.694	7
W3	2	20	42	48	15	0.685	8
W10	2	20	44	47	14	0.680	9
W11	5	18	47	44	13	0.666	10
W12	2	24	44	48	9	0.660	11
W14	3	23	45	50	6	0.652	12
W13	4	31	42	33	17	0.644	13
W15	5	29	43	41	9	0.631	14
W9	6	30	49	33	9	0.614	15

shows RII of CW causes related to the role of PMs in highway projects.

5. Discussion

Our findings show an average perceived CW percentage of 8.5%, which, by volume, would be enormous due to the huge quantities of materials consumed in road projects. This highlights the need for effective intervention strategies to minimize wastage. PMs were identified as the most important and influential stakeholders in waste reduction efforts, as their decisions and competencies have a significant impact on project sustainability. The most critical causes of waste can be addressed by PMs by influencing quality control, communication, and resource management. These results align with the existing literature, which emphasizes the PM’s central role in ensuring operational performance and efficiency. Additionally, the study proposes a conceptual waste minimization framework that links specific waste causes to corresponding PM roles and actionable strategies based on opinions of experts (three from industry and two from academia). The recommended framework constitutes the most significant causes of construction waste and their corresponding project management (PM) competencies, waste-minimizing measures, and strategies (see

Table 3. CW minimization framework (measures and management strategies corresponding to roles of PM).

Most Significant Waste Causes	Role/Competencies of PMs Requiring Improvement	Waste-Minimizing Measures	Waste Management Strategy
Faulty work requiring the work to be carried out again	Quality Management	Skilled labor Site control	Visual management Onsite control Training
Wrong construction methods	Knowledge of Construction	Skilled staff Availability of machinery	Knowledge management Innovative methods of construction
Lack of awareness	Communication	Training	Training
Poor supervision of work	Quality Management	Use of technology/innovation Skilled supervisors	Visual management Onsite control Training
Poor material planning	Resource Management	Proper planning and scheduling Management of materials	Procurement planning Inventory management

).

6. Conclusions

Highway construction projects produce substantial material waste due to intensive consumption of materials, posing a serious threat to project sustainability and efficiency. Project team members play a crucial role in reducing this waste, with project managers (PMs) considered the most influential. This study aimed to examine the causes of construction waste in highway projects that fall within the scope of PM responsibilities, a topic that remains underexplored, particularly in the context of Pakistan’s highway sector. A quantitative methodology was employed using a structured questionnaire distributed to highway construction professionals. The study assessed perceived material wastage, compared the influence of key team members on waste reduction, and identified critical waste causes linked to PM competencies through the Relative Importance Index (RII). The findings revealed that 6–10% of construction materials are typically wasted in highway projects. PMs were rated as the most impactful project team members in waste management. The top five causes of waste associated with PM roles were faulty work requiring work to be carried out again, use of wrong construction methods, lack of awareness, poor supervision, and poor material planning. These causes are directly linked to key PM competencies, including quality management, communication, resource management, and construction knowledge. Based on these insights, this study proposes a waste minimization framework outlining specific measures and management strategies tailored to PM responsibilities. This exploratory research contributes to a better understanding of PMs’ roles in reducing construction waste and offers practical guidance for enhancing sustainability in highway projects.