Barriers to Achieving Sustainability in Highway Construction Projects: The Case of Jordan

Abstract

Despite the importance of sustainable highway construction projects in achieving sustainable development, unsustainable construction highway projects still prevail in Jordan. Therefore, this article aims to identify barriers affecting sustainability implementation in Jordan’s highway construction projects. These barriers were identified from the previous literature. Questionnaire surveys were developed and distributed to experts to rank the degree of importance of each barrier. Moreover, a case study was assessed to evaluate the sustainability level of highway projects in Jordan. The research found that the sustainability concept should be supported financially to protect the environment by using a legislative framework to implement sustainability principles. There are several barriers to implementing the concept, like the lack of sustainability education, improper communication amongst team members, and the lack of familiarity with the techniques and the necessary skills to employ them properly. The use of sustainability assessment tools is needed to evaluate the sustainability level for highway projects. For the case study, a sustainability assessment tool was applied to the most recent important highway project in Jordan, “Bus Rapid Transit project,” to determine its sustainability level and to show how the barriers affect the implementation of the sustainable highway project and lower the sustainability level in the project.

1. Introduction

Highway construction is a major human activity. Unless transportation networks are strengthened, economic growth will be hampered. It improves the economy by reducing travel time, lowering transportation costs, increasing access to products and services, and creating new job possibilities. Several decades ago, the primary obstacles were technological and operational. Engineers and contractors did not have to think about the environment. Nevertheless, environmental concerns have become prevalent. As a result of new highway buildings, the environment is negatively impacted in both the short and long term [1].

According to the broad definition of sustainable development (World Commission on Environment and Development, 1987), mobility is a technique, not an end, in a sustainable transportation system. Determining how to achieve ecologically friendly transportation requires fresh, creative ideas from all strata of society and economic sectors [2].

A sustainable transportation system adheres to social, economic, and environmental sustainability principles. Anybody may use them, and they satisfy the general public’s demand for safe transportation while simultaneously protecting the environment and fostering social equality [1]. More sustainable highways mean less environmental effects, lower impacts on the life cycle, and better social results. The environment comprises the important surrounding conditions (landscape). Therefore, the roadway must be seen as part of a symbiotic arrangement that involves infrastructure and nature [3].

Sustainable highway projects support economic development while meeting society’s transportation needs and respecting natural laws and human values. Two elements must be considered; first, sustainability measures are responsive to the project’s socio-economic setting. Second, a fair definition of sustainable highway projects includes conception, operation, maintenance, and recycling/reuse [4].

Researchers prioritize social well-being over material riches, as measured by gross domestic product. Although there is no widespread agreement on the specific definition of sustainability, it is acknowledged that development to improve people’s living standards (broadly defined) must be conducted so that uncompensated future costs are minimized. The main concept is to consider social, environmental, and economic aspects while making decisions [1].

A sustainable system supports some significant issues to provide decreasing resource components, inputs, disposal outputs, and minimizing transportation failure effects in the public dimension [5]. Social and technical implications include improved fuel efficiency and lower emissions that affect traffic movement on major highways; nonetheless, they are not essential for sustainable transportation. Furthermore, sustainable transportation strives to reduce financial expenses to the government and individuals by reducing reliance on vehicles as the primary mode of individual movement [6].

The enormous amounts of solid waste generated in major cities have become a severe concern. Incineration may significantly decrease the amount and weight of solid waste and generate power, making it a more sustainable option than conventional landfilling [7]. The use of solid waste as an alternative construction material recycles waste, such as producing blocks and ceramics using soil and industrial solid waste [8].

Business as Ever (BAE) in transportation claims that highways have been built and expanded to minimize traffic congestion [9]. Over the previous decades, the development of many additional bus stations and terminals has been facilitated by sustainable improvement in traffic and states, consolidation of transportation modes, and resuscitation of subway traffic [10].

The term Triple Bottom Line (TBL) was coined for the first time in 1994 by John Elkington, the founder of a British consultancy called “SustainAbility” in a California Management Review article, and it was developed and extensively defined in 1998 in a book titled Cannibals with Forks: the TBL of 21st Century Business [11]. The TBL stems from the sustainable development paradigm and is focused on the pursuit of balance across three dimensions: economics, ecology, and ethics [12]. Elkington’s concept was that firms should be generating three primary (and different) bottom lines. The first is the standard measure of business profit—the “bottom line” of the profit and loss statement, which refers to Economics. The second is the bottom line of a company’s “people account”—a gauge in some shape or form of how socially responsible a business has been throughout its activities, which refers to the social factor. The third is the bottom line of the company’s “planet” account—a measure of how environmentally responsible it has been, which refers to the Environment [13].

The TBL is also represented graphically as a Venn diagram integrating environmental, economic, and social systems [14]. These three systems are sometimes called “the three Ps” (people, planet, and profit) or “the three Es” (equity, environment, and economics).

In the literature, this paradigm is known as the 3P—people, profit, and planet—concept. Its purpose is for commercial organizations’ activities regarding the environment and the social sphere to be considered financial outcomes, and therefore clearly settled regarding the performance in these aspects. This goal is rooted in the belief that we only care about what we must look after and what we need to settle. The term “bottom line” relates to a company’s profitability or the field of economics. The social and environmental fields are also included in the triple bottom line [12].

The TBL is an unpleasant idea for many companies because it emphasizes that its obligations extend well beyond the financial measures of improving the efficiency that consumers desire, by regulatory requirements, and at a profit. The TBL adds social and environmental performance indicators to the economic measures usually employed in most companies. Environmental performance typically refers to the amount of resources a company consumes in its operations (for example, energy, land, and water) and its byproducts (e.g., waste, air emissions, chemical residues, etc.). Social performance can be defined as the company’s impact (and its suppliers) on the communities in which they operate. Performance measurement against these factors is not an easy process. Shareholder value, market share, customer satisfaction, and even employee health is relatively measurable; instead, measures developed by one organization are helpful to others. However, social and environmental performance is almost precise to the company or each industry, and they are frequently difficult to quantify [15].

Therefore, this research aims to study the main barriers behind implementing sustainable highway construction in Jordan, and the sub-objectives are to:

• Identify barriers to implementing sustainability in the Jordanian highway construction.
• Evaluate the level of sustainability of the actual highway project in Jordan.

2. Literature Review

2.1. Sustainability in Jordan

Jordan is located in the Eastern Mediterranean region and has a land area of approximately 89,300 km². Most of the population is situated along the mountain ranges, including the following major cities: Irbid, Zarqa, Amman, Salt, Madaba, and Karak. Amman is Jordan’s capital city, and its population accounted for around 43 percent of the Jordanian population in 2018 [16].

The country suffers from a lack of natural resources, mainly freshwater resources, which are declining at an alarming rate due to unsustainable groundwater extraction and a downward trend in precipitation in the current years [17].

Jordan’s economic and social well-being is inextricably tied to its country’s political standing and relationship with its neighbors [18]. Moreover, the economic development strategy is unsustainable according to the country’s dependency on fuel imports, which, given the region’s politically unpredictable situation, would lead to energy insecurity [19].

A legislative system of rules and regulations was formed in Jordan targeted at environmental preservation. In addition, international agreements and conventions adopted procedures, protocols, and standards to protect the environment and its many aspects from pollution generated by various industrial, agricultural, and service businesses [20].

Jordan is an example of a developing nation dealing with urbanization issues and a goal to support sustainable growth to enhance living conditions. However, population growth and urbanization have had adverse long-term effects on all aspects of the country’s economy, ecology, social life, and politics. In addition, this growth has led to increased demand for resources and increased competition for scarce resources [21].

Recently, sustainability challenges have started to assume a more prominent position on governmental agendas. However, social sustainability issues seem to be weak, underlining the importance of undertaking appropriate steps to strategically manage social requirements, as the majority of efforts so far have been unsatisfactory. Ignorance of good social issue management and appropriate physical environment building resulted in severe consequences for public facilities and services, hurting people’s quality of life [22]. Uncontrollable urban growth negatively influences people’s economic well-being and quality of life in Jordan because of rising demand, poor economic conditions, and a lack of precise control over urban planning [23]. As a result, Jordanian cities have serious problems with the surrounding environment regarding people’s health, community services, social cohesion, and human rights [24].

Immigration from neighboring countries has caused the infrastructure to be affected by sudden increases in population. Due to the rapid growth of the population, the transportation system could not meet the needs of the people. As a result, the system has become unstable and prone to many traffic accidents and high congestion [25].

Rapid population expansion in Jordan, especially in Amman, along with unplanned urban sprawl have further reduced mobility and accessibility, increased traffic congestion, and undermined the city’s limited public transportation infrastructure. The harmful environmental (both pollution and noise) and safety consequences of increased traffic are also significant [26].

In 2015, the annual mean of fine particulate matter (PM_2.5) concentration in Amman was 40 µg/m³ (micrograms per cubic meter of air), exceeding the World Health Organization (WHO) standard of 10 µg/m³ and above the national limit 15 µg/m³. The most recent data for 2017 from the same source indicates a significant drop to 28 µg/m³, yet this still falls short of the national limits [27].

Greenroads solutions in cities will decrease emissions and pollutants, improve quality of life, save money, and raise public knowledge of sustainable mobility and renewable energy systems [28]. Therefore, the proper solution is to implement the concept of sustainability and the new sustainable technologies considered while designing a new highway project. For example, according to [29], the use of waste tire rubber and porous asphalt mixes resulted in lower abrasion loss, optimal asphalt contents, improved hot temperature performance, water, aging, and skid resistance.

From this point of view, the Jordanian government recognized the need for an effective public transit system and has been working on constructing a Bus Rapid Transit (BRT) network in Amman. Furthermore, the government collaborated with the Ministries of Public Works and Transport to connect the Amman BRT to the projected Amman–Zarqa BRT [26].

The construction industry is considered a major cause of many environmental damages as it consumes many natural resources [30]. So, the introduction of the sustainability concept in this area is necessary to enhance the quality of highways and evaluate the sustainability level for the case study in Jordan. BRT systems are positioned as critical interventions capable of facilitating social justice, poverty reduction, and vertical equity among urban populations, the main sustainability concepts [31].

2.2. Greenroads Assessment Tool

Greenroads is the overarching concept for sustainable infrastructure construction research and development programs. It was developed by Cornell, Howland, Hayes, and Merryfield at the University of Washington in 2009 [32]. Greenroads system goals are (1) water use and water management; (2) energy and emissions reductions; (3) the use of recycled, reused, and renewable components; (4) conservation and management of the environment; and (5) economic social benefits [33].

A total of 49 voluntary items up to 130 points within six categories, known as "voluntary credits," will be planned. These categories are (1) Environment and Water; (2) Construction Activities; (3) Material and Design; (4) Utilities and Control; (5) Access and Livability; and (6) Creativity and Effort [34].

Table 1. Greenroads V2 credits (source: www.greenroads.org (accessed on 6 March 2022)).

Category Name	Credits	Points
Project Requirements (PR)	12	0
Environment and Water (EW)	10	30
Construction Activities (CA)	11	20
Materials and Design (MD)	6	24
Utilities and Controls (UC)	8	20
Access and Livability (AL)	10	21
Total Main Categories	57	115
Creativity and Effort (CE)	4	15
Total with CE	61	130

summarizes the type and point for each main category and its credit points.

The Greenroads research and development process resulted in assigning weights for each task based on the data collected that reflect each practice’s ecological, economic, and social effects over its lifespan. There are between 0 and 5 points for each voluntary task. Voluntary credit that has higher impacts on sustainable construction has higher values. The documentation of all project requirements and collecting several voluntary approvals to meet the thresholds for each award will deliver four levels of achievement: Bronze, 40 voluntary credit points (31%); Silver, 50 voluntary credit points (38%); Gold, 60 voluntary credit points (46%); and Evergreen, 80 or more voluntary credit points (>62%) [34].

3. Methods

This research is designed to identify barriers to implementing sustainability in Jordanian highway construction and to evaluate the level of sustainability of an actual highway project in Jordan. For this purpose, previous sustainability-related research papers were reviewed to generate a preliminary list of barriers—see

Table 2. Previous related research for barriers to implementing sustainability concept.

Barrier	Previous Research
	[36]	[5]	[37]	[38]	[39]	[40]	[41]	[42]	[43]	[44]	[45]	[46]
B1: The design team members did not understand that “sustainability” is a philosophy, not an architectural style.	√					√					√
B2: Contractors may lack skills, knowledge, and information on sustainable highway design and construction, as well as sustainable products and procedures.	√	√			√	√	√	√	√	√	√	√
B3: In Jordanian universities, there is a lack of education regarding sustainable design and construction, and developers do not educate or train about the sustainable development.	√	√			√		√
B4: Jordanian engineers have a lack to exposure to current resources and knowledge of sustainable highway design and construction.	√						√
B5: Architects, designers, the construction industry, consumers, and other stakeholders are unaware of the concept of sustainability and how critical it is.	√	√			√	√	√	√	√	√	√	√
B6: Improper communications exist among members of the design or execution teams.	√	√				√		√		√
B7: Limited knowledge of the long-term economic benefits of sustainable design and construction.	√						√		√		√	√
B8: Sustainable building design and construction are more expensive, so owners usually prefer relatively quick payback times because of the higher initial construction costs.	√		√	√		√	√	√	√		√	√
B9: Lack of familiarity with the techniques and the necessary skills to employ them properly.		√				√		√	√		√
B10: High time consumption in using the techniques.	√	√				√		√	√
B11: Limited programming software needed to implement the concept.		√									√
B12: Difficulties in handling the risks that will be incurred affect the construction activities.		√				√			√
B13: Uncertainties concerning the future worth of the project.		√
B14: Jordanian engineers are hesitant to use natural resources in their varied tasks (water, air, sun… etc.).					√					√

. Additionally, questionnaire surveys were conducted to rank the identified barriers. A survey was used to collect data. The collected data were evaluated using frequencies, means, statistics, and the Relative Importance Index (RII). After that, the sustainability assessment tool “Greenroads” was applied to the most recent important highway project in Jordan, “BRT project,” to determine its sustainability level by using a web application for self-assessment on its official website. Finally, six interviews were performed with experts working in the highway construction industry to discuss the barriers and suggest proper solutions.

3.1. Data Collection

Data concerning the barriers were obtained from many previous related research papers, as shown in Table 2. The main tool for data collection was a survey via a structured questionnaire that was tested by conducting a pilot study. This questionnaire consisted of two sections; the first section obtained demographic data from participants. For the second section, respondents were asked for the degree of agreement for each barrier according to their contributions in highway construction industry to implement sustainability concept based on a 5-point Likert scale (varying from 1: strongly disagree to 5: strongly agree).

The surveys were distributed to 345 individuals (managers, academics, experts, and engineers) experienced in the highway construction industry from several companies in public and private sectors, and 240 participants (68 percent) completed the survey. A statistical analysis was conducted to determine the sample size based on “Table for Determining Minimum Returned Sample” [35]; therefore, the sample size was 242, and 240 participants is adequate.

In this study, 79% of the respondents were experienced in highway construction, infrastructure, and buildings projects. The remaining 21% were experienced with several other roles such as the design phase, manufacturing, logistics, and management. Notably, 60% of the respondents had more than five years of experience, and 25% had a Ph.D. or master’s degree.

3.2. Data Analysis

The RII method was used to assess the barriers according to respondent’s degree of agreement. A Likert scale (5-point) ranging from 1 to 5 was used to assess the significance of each barrier. RII was considered only when a significant relationship existed between each barrier and the implementation of the sustainability concept. RII was calculated with the following equation for each barrier. The geometric mean was determined for all RII values of each barrier. A higher RII value means a more significant barrier to implementing the sustainability concept in highway construction industry.

$$\mathrm{RII}=\frac{{{\displaystyle \sum }}_{\mathrm{i}=1}^{\mathrm{N}}\mathrm{Wi}}{\left(\mathrm{A}\times \mathrm{N}\right)}$$

where W = weight of agreement of each barrier to implementing sustainability concept, A = the maximum weight (5) in this study, and N = total number of participants.

The barriers were ranked after calculating the RII value for each one. RII represents the significance of the agreement of each barrier in the implementation of the sustainability concept.

3.3. Applying Greenroads for the Case Study

Applying the Greenroads rating system has become essential in some countries. The Greenroads rating system could provide a valuable and systematic way to tackle the issue of sustainability in a highway construction project using a quantitative approach that may influence decision making [47]. This research found that the Greenroads assessment tool is more proper for the barriers in this study compared with INVEST rating systems because the components of each are different.

The application of the Greenroads assessment tool requires registering the project by filling in the user’s information. A free web app for self-assessment needs to be filled in by the user based on the guides on the official website for Greenroads (www.greenroads.org (accessed on 6 March 2022)).

4. Results

4.1. RII Values for Barriers

The RII values were calculated for the barriers based on the equation presented and described in the data analysis section. The final RII values for the barriers are shown in Figure 1.

The RII values were used to rank the barriers to identify the most significant ones. Barrier B3 was assigned to the first rank, with an RII value of 84 percent. Barriers B6 and B9 are on the second and third ranks, with RII values of 83 and 80 percent, respectively.

4.2. Sustainability Assessment for Amman–Zarqa BRT Project Using Greenroads Rating System

The Greenroads tool needs some input to determine the score for the case study to certify its sustainability level. While using the free web app for self-assessment, some information is needed, such as project name, city or country, project budget, and status (planning, design, construction, complete). After completing this information, answers for 12 project requirement questions and scores for items in 6 different categories are required.

Table 3. Greenroads project requirements assessment for the Amman–Zarqa BRT project.

Category	Credit ID	Description	Assessed Score	Case Study (BRT) Notes
Project Requirements	PR-1	Ecological Impact Analysis	Yes	The construction activities were conducted under the client representative’s direct supervision to prevent any violation of approved standards.
	PR-2	Energy and Carbon Footprint	Yes	The operation of BRT aimed to reduce the traffic jams and the use of modern buses that reduce the overall operational emissions.
	PR-3	Low-Impact Development	Yes	The design of stormwater systems was included in the two sides of the project’s main road, and its construction was all conducted as planned.
	PR-4	Social Impact Analysis	Yes	The potential social impacts of BRT project on the surrounding communities were controlled by complying with the requirements of accessibility, safety, equity, community, engagement, and economic development.
	PR-5	Community Engagement	Yes	BRT project teams were engaged with the community and stakeholders throughout the project’s lifecycle.
	PR-6	Lifecycle Cost Analysis	No	Evaluating the cost estimation processes and the financial planning, assessing the costs over the entire life cycle (construction, maintenance, operation), considering the impact on the local economy (job creation, improved accessibility). BRT project faced some unseen barriers in the construction phase, causing additional costs over the budgeted costs.
	PR-7	Quality Control	Yes	Reviewing the documentation, records, and assessing the implementation and effectiveness of quality control measures. BRT’s site laboratories collaborated with other sectors to conduct inspections and testing for all construction activities to verify compliance with specifications, codes, and industry standards including materials testing, structural inspections, and other activities.
	PR-8	Pollution Prevention	Yes	PR-8 aims to assess the BRT’s efforts to reduce air and water pollution, and soil contamination. BRT minimized pollution during construction activities by using low-emission equipment, implementing dust-control measures, stormwater management, proper handling, and disposal of hazardous materials, and conducting regular soil testing.
	PR-9	Waste Management	Yes	PR-9 aims to evaluate the BRT’s efforts to manage construction waste effectively. In the excavation activities, the removed materials were used for filling in activities in other areas in the project by segregating the amount in the site using special equipment. The disposable materials were transported to approved areas designated for that purpose.
	PR-10	Noise and Glare Control	No	BRT project did not use noise barriers or other mitigation techniques during the construction phase to reduce noise levels generated by it.
	PR-11	Utility Conflict Analysis	Yes	Different teams (client, consultant, contractor) conducted a wide study for all existing utilities that may intersect with the proposed BRT project alignments beside the coordination with all stakeholders to minimize disruptions and ensure the safe and timely relocation or adjustment of utilities.
	PR-12	Asset Management	Yes	The client, via coordination with contractors, has maintenance and repair strategies including routine maintenance activities, timely repairs, and proactive interventions to optimize performance.

and

Table 4. Greenroads main categories assessment for the Amman–Zarqa BRT project.

Category	Credit ID	Description	Assessed Score	Total Points
Environment and Water	EW-1	Preferred Alignment	1	3
	EW-2	Ecological Connectivity	1	3
	EW-3	Habitat Conservation	2	3
	EW-4	Land Use Enhancements	2	3
	EW-5	Vegetation Quality	1	3
	EW-6	Soil Management	2	3
	EW-7	Water Conservation	1	3
	EW-8	Runoff Flow Control	1	3
	EW-9	Enhanced Treatment: Metals	1	3
	EW-10	Oil and Contaminant Treatment	1	3
Construction Activities	CA-1	Environmental Excellence	1	3
	CA-2	Workplace Health and Safety	2	2
	CA-3	Quality Process	1	3
	CA-4	Equipment Fuel Efficiency	1	1
	CA-5	Workplace Air Emissions	0	1
	CA-6	Workplace Water Use	1	3
	CA-7	Accelerated Construction	1	2
	CA-8	Procurement Integrity	1	1
	CA-9	Communications and Outreach	1	1
	CA-10	Fair and Skilled Labor	1	2
	CA-11	Local Economic Development	1	1
Materials and design	MD-1	Preservation and Reuse	2	5
	MD-2	Recycled and Recovered Content	2	5
	MD-3	Environmental Product Declarations	1	2
	MD-4	Health Product Declarations	1	2
	MD-5	Local Materials	2	5
	MD-6	Long-Life Design	1	5
Utilities and Controls	UC-1	Ecological Impact Analysis	1	2
	UC-2	Energy and Carbon Footprint	1	1
	UC-3	Low-Impact Development	1	3
	UC-4	Social Impact Analysis	1	3
	UC-5	Community Engagement	0	3
	UC-6	Lifecycle Cost Analysis	1	3
	UC-7	Quality Control	1	3
	UC-8	Pollution Prevention	1	2
Access and Livability	AL-1	Waste Management	0	2
	AL-2	Noise and Glare Control	1	2
	AL-3	Utility Conflict Analysis	1	2
	AL-4	Asset Management	1	2
	AL-5	Preferred Alignment	0	2
	AL-6	Ecological Connectivity	1	2
	AL-7	Habitat Conservation	1	3
	AL-8	Land Use Enhancements	1	2
	AL-9	Vegetation Quality	0	2
	AL-10	Soil Management	0	2
Creativity and Effort	CE-1	Water Conservation	1	2
	CE-2	Runoff Flow Control	1	5
	CE-3	Enhanced Treatment: Metals	2	5
	CE-4	Oil and Contaminant Treatment	2	3
Total Score			53	130

, respectively, summarize the project requirements and the main category assessment processes for the case study based on the Greenroads rating system. For the BRT project, the assessment process was achieved by evaluating each credit in Greenroads and accumulating points from the project team and combining them with scores from other categories to determine the overall sustainability score of the project.

Twelve project requirements and forty-nine other categories were assessed for the case study. Each of them was rated based on the actual situation and available resources of the BRT project to complete all self-assessment processes with total of sixty-one categories.

5. Discussion

5.1. The Most Significant Barriers to Implementing Sustainability in Jordan

The first-rank barrier, B3, implies that there is a lack of education regarding sustainable design and construction, and this result complies with [48], which confirmed the necessity of training courses in sustainable construction for construction company workers. Nevertheless, Ref. [49] concluded a lack of integration of sustainability issues in education and training programs. Meanwhile, Ref. [41] stated that the sustainability concept for highways in Malaysia is still not understood, and a green highway is less pleasing and undervalued by the development community.

The second-rank barrier, B6, indicates that improper communication occurs among members of the design or execution teams. Study [42] stated that project managers reported issues with the lack of communication and interest among project team members, considering it a main challenge in Singapore. Also, the results of [48] show that the lack of a proper communication system is a high-ranking barrier to sustainability implementation in Jordan.

The third-rank barrier, B9, suggests that there is a lack of familiarity with the techniques and the necessary skills to employ them properly. As stated in [45], frequently, construction workers with lower levels of qualification generally misunderstand the concept of green building. Transportation security and safety are highly sensitive subjects that impact both the customers and suppliers of transportation [50].

5.2. Greenroads Assessment Discussion

The results of the self-assessment using Greenroads V2 were:

• Requirements Met: Maybe.
• Target Score: Minimum Project Requirements Not Met (53).
• Target Rating: Silver (53 > 50).

As described in Table 3, the BRT project did not meet all the sustainability needs, but its score was 53 out of 130 points, which attains a Silver certificate for the case study. The score was based on the collected data from the questionnaires and the interviews. Since this exercise was the first for the BRT project, stakeholders in this field might be more aware of the sustainability concept in future projects.

6. Conclusions

In Jordan, highway projects suffer from several problems that affect their users due to a lack of proper planning, wrong decisions, and inefficiency during the planning and construction phases. The case study in this work is the BRT project, which links the cities Amman and Zarqa in Jordan. These cities have suffered from poor service levels on the main connecting roads for several years, so the BRT project was initiated in 2018 to reconstruct and enhance these main highways.

The main barriers to achieving sustainability in highway construction were highlighted throughout this paper. These barriers are summarized as follow:

• First-ranked barrier (B3): Lack of education regarding sustainable design and construction.
• Second-ranked barrier (B6): Improper communication among members of the design and execution teams.
• Third-ranked barrier (B9): Lack of familiarity with the techniques and necessary skills to employ sustainable practices.

To overcome these barriers, we pose several recommendations, such as:

• Introducing sustainability concepts into various engineering educational fields;
• Adopting new regulations towards sustainable practices within the construction industry, such as using recycled materials, renewable energy, and green construction techniques;
• Providing financial support and incentives, and lowering taxes for sustainable projects;
• Selecting contractors based on their work quality rather than price solely;
• Using sustainability assessment tools to evaluate the overall level of sustainability for highway projects to accumulate lessons learned for future projects.

One of the main limitations of this study is that the sustainability concept in highway construction is relatively novel in Jordan, so no previous studies are available in Jordan to use as a benchmark or compare to this study.

This study focuses on the challenges that the sustainability concept faces for highway projects in Jordan, using the BRT project as a case study. Future research could compare the BRT in Jordan and other BRT projects in Jordan or other countries. The same tools used in this research could be applied to highway construction projects in Jordan. Future studies could evaluate the sustainability of the Amman–Zarqa BRT (or any other) highway construction project using assessment tools other than the one adopted in this study.