Risk Response in Construction Project: A Review Study

C onstruction projects are characterized as projects with multi phases and activities, complex, unique, and have many different parties and stakeholders. Risks could appear at one or more of the construction project stages and may affect the achievement of project objectives. Therefore, one of the key elements in the planning phase of any project is the risk management process (RMP). This study attempts to understand the terminology of risk in general, risk management, and response to risk in particular. This study is mainly a review of thirty-eight studies that have been published between 1997 and 2020 that demonstrate the importance of the crucial phase of risk response from the risk management process and its impact on the project objectives, as well as the tools and methodologies that project managers and decision-makers could use to handle the risks to reduce the negative effects of risks on the success of the construction projects. This study concludes that risk response should be considered an essential activity to complete the RMP, which will lead to minimizing the losses due to risks, maximizing the benefits due to opportunities, and achieving the objectives of projects.


INTRODUCTION
A project is a temporary endeavor to create a unique service or result. A project is a series of activities that should be done within an acceptable time, cost, and desirable quality. Project management is the use of specific knowledge, skills, tools, and techniques to deliver something of value to people (PMI, 2022) and that leads to all projects should be managed properly by using the right resources: equipment, material, different team members in all phases of any project. Projects cannot be performed in a deterministic environment since risks and uncertainties could be generated and may affect the project objectives, parties, or even the project's success. Risk management should be planned tightly and equipped with the right skills and techniques to identify the potential risks, assess the risks quantitatively and qualitatively, and develop strategies to address the risks to reduce or eliminate the occurrence or the negative impacts of risk events. Risk response strategies play a proactive role in either preventing the risks or making the project adapt to risks or both ways. The main objective of the risk responses stage is the success of the project and team members in confronting the risk with the right responses, so that would not be achieved without hiring experienced managers and trained team members, using appropriate techniques to choose, implement, monitor, and control the proper responses to address the risks successfully. To validate the hypothesis of this study, which believes in the importance of the risk response phase from the risk management process and how this phase must be given the attention it deserves during the planning and implementation of various types of construction projects. This work focuses on reviewing previous studies that dealt with the risk response stage and presenting the objectives and tools adopted in each study. This work seeks to emphasize the importance of understanding the stage of risk response in risk management and give it sufficient attention in planning and implementing the risk management process in all types of construction projects. Fig. 1 represents the systematic literature review used in the study.

Figure 1. Research Methodology
Through the search process, it was found that there is a clear discrepancy between the number of research papers that dealt with the concepts, types, identification, and evaluation of risks, how to plan and implement the phases of the risk management process, and the research papers that concerned with the risk response phase. Studies about the risk response stage were less numerous compared to investigations related to risk identification and assessment stages. The keywords adopted in the selection of previous studies were: "risk response in construction projects "to highlight this important stage which has a major role in the success of any project and achieving its goals. The period for the selected papers is from 1997 to 2020. Fig. 2 illustrates the growing interest in risk response through the increasing number of studies proposing new frameworks to plan, select, and evaluate risk responses. To review what previous researchers have presented in the field of risk response in construction projects, Thirty-eight research papers were selected from different countries around the world, such as Australia, China, Canada, Egypt, Europe, Fiji, Iraq, Iran, Japan, Palestine, South Africa, Turkey, United Arab Emirates, United States of America and the United Kingdom.

DEINITION OF RISK
Risks always accompany the execution of project phases. The risks could become more difficult according to the complexity degree of the project. Project complexity can be defined as the degree of differentiation between project components, the interdependence of project components, and the influence on project decisions (Hossny et al., 2021). So project complexity depends on the type, characteristics, and project requirements. Risks can be classified into different groups according to their sources, effect, and project activities such as: (Burhan, 2003; Ehsan et al., 2010; Al-Ajmi and Makinde, 2018; Rasheed, 2015a; Al-Mukahal, 2020)  External and internal risks  Acceptable and unacceptable risks  Manageable and unmanageable risks  Risk discipline; technical, logistical, environmental, financial, socio-political, and management-related risks Because of the importance of understanding the concept of the term risk, many researchers have studied risks and defined them from their point of view, as shown below:  Risk is the exposure to the potential of fiscal loss or gain, physical damage, or delay due to the uncertainty associated with a particular action. No.
of studies  Risks are a combination of events that negatively affect the project objectives and can be associated with operational, technical, or commercial aspects of the project (Singh et al., 2017)  Risks are uncertain events that adversely affect the project objectives and can occur at any phase in any construction project (Abu Safayet et al., 2018)  Risk is the probability of any problem in the future that could affect the project plan, and then the project will deviate from the planned schedule (Nassar, 2021)  A risk is an uncertain event that may impact one or more of the project objectives positively or negatively, and it must be handled to maximize the positives and minimize the negatives. (Kadum, 2021) The researchers concluded that risk could be defined as an external or internal event that may occur in one or more of the construction project phases, and this event may negatively influence achieving project requirements and objectives.

Definition
Construction projects can be described as risky business. Confronting risks is a heavy burden for project managers and team members to deal with, and from this, the significant role played by risk management in construction projects appears. Project Management Body of Knowledge(PMBOK) puts risk management as one of its nine knowledge areas in project management; integration, scope, time, cost, quality, human resource, communication, risk, and procurement. Risk management has many different definitions according to the previous studies, as illustrated below:  Risk management is a system to identify, evaluate, categorize risks and make the risks explicit (Anthony, 1996, as cited in Abu Safayet et al., 2018)  Risk management is a critical element of any successful management process (Chavas, 2004)  Risk management is an attempt to identify threats, the probability of their occurrence, appropriate responses to address them, and take the necessary actions to reduce their occurrence (Mcnamara, 2008)  Risk management is a systematic approach to addressing unknown events by taking the necessary steps to protect the assets and objectives of the organization from being adversely affected by external or internal events (Sharma and Swain, 2011)  Risk management is a process of risk identification assessment and implementing appropriate strategies to reduce them to an acceptable level. Risk management should be applied in projects to improve the project management process (Banaitiene and Banaitis, 2012)  Risk management is an effective approach used in the Management of construction projects to maximize the probability of completing the project successfully (Rasheed, 2015b)  Risk management means the entire process of managing project risks that cause adverse impacts on the project objectives (Fukuda and Kuwano, 2017)  Risk management is a process consisting of negative risk identification, risk impact quantification, and implementation of actions to mitigate the impact of risks (Singh et al., 2017)  Risk management is a process that aims to manage and decrease the risks facing an organization (Nassar, 2021)  Risk management is a systematic process aimed at identifying and managing risks to achieve project objectives and improve communication between project parties (Kadum,

2021)
The researchers have defined risk management as one of the success elements for all types of construction projects that must be used to identify, analyze, and propose responses to eliminate negative impacts and increase positive impacts in achieving the objectives of projects.

Process
Many different processes are proposed for risk management according to the project phase's division. The number of risk management process stages differs from one study to another according to the perspective of researchers that have been presented in their research papers, as clarified: The risk management process consists of the following:

RISK RESPONSE DEFINITION
In the risk management process, after risks are identified, quantified, and qualified, the next step should be determining actions to address the evaluated risks. The risk response phase includes planning, monitoring, and controlling the determined actions to reach the required result.
Many researchers attempt to clarify the risk response phase according to their point of view by developing a suitable and understandable definition for it, such as:  Risk response is developing actions to improve opportunities and minimize threats to project objectives. From the researchers' point of view, risk response is a critical and vital stage in project risk management, and it involves developing appropriate responses to reduce or eliminate threats and increase opportunities from the identified and evaluated risks in the early stages of the risk management process.

STRATEGIES OF RISK RESPONSES
To deal with risks in construction projects, (Ehsan et al., 2010; Kadum, 2021; Singh et al., 2017; Rasheed, 2015; Bransah, 2020) have reviewed the following strategies for risk responses that would be helpful to use one or more of them:  Avoiding means removing the threats of risks by not doing part of the actions that include risks or changing the project plan.  Accepting means accepting the risk and not taking any action unless the risk occurs. This method can be useful in situations when the consequences of the risk are cheaper than the cure.
 Mitigating and reducing: it is about reducing the negative impact of risks on the project by educating and training project team members and enhancing the working environment.  Transferring: This strategy refers to passaging the responsibility of doing the work and resolving risks to third parties.  Sharing: the concept of this method is to share the risk responsibility with other partners across different teams or projects, so the risks would be handled by the partners who think these risks are within their capabilities.  Removing: it refers to eliminating the risks by removing their causes.

LITERATURE REVIEW RELATED TO RISK RESPONSE
For the first time, risk response to the project was presented by (Chapman, 1979), who introduced a systematic work breakdown structure WBS-based approach to analyze, assess, and respond to risks. proposed a multi-party risk management process to help in the decision-making process efficiently and systematically risk Management within the multi-part environment by using trade-off approach. (Ben-David and Raz, 2001) presented an optimization model that integrated project work breakdown structure (WBS), risks, risk reduction actions, and their impacts into a framework. The model represents the overlapping impacts of risk reduction actions, and the effects of secondary risks, as well as the model supports the assessment of the risk exposure of the project under different risk reduction actions. (Kujawski, 2002) used Trade, Decision trees, Monte Carlo simulation, and Cumulative risk profiles to propose a mathematical approach that: links the risk response action to contingency planning and the success probability and supports decision-makers toward risk mathematically and practically.

6.2.
Literatures from 2003 to 2008 (Haimes, 2005) focused on two factors: 1) the cost of the risk response method, 2) the work losses percentage related to the risk response strategy. (Kayis et al., 2007) used five heuristic algorithms to find feasible solutions for risk mitigation. The developed approach aims to support project managers in selecting the best mitigation strategy within the budget constraints and project objectives. (Fan et al., 2008) made a conceptual framework that explains the quantitative relationships between project characteristics and risk-handling strategy. The analysis is performed to find the minimum cost of risk responses for each risk event using optimization and mathematical modeling. (Kılıç et al., 2008) proposed a mixed integer programming model to address the problem of the impact of risks on project scheduling. The main objectives of the optimization model were to minimize both: 1) expected makespan and 2) total cost. A genetic algorithm (GA) was used to solve small problems, and that experiment showed that GA was a fast and efficient approach. To minimize the losses due to risks, (Sherali et al., 2008) presented an optimization model to assign obtainable resources for risk mitigation actions.

Literatures from 2009 to 2014
An article by (Seyedhosein et al., 2009) provides a methodology incorporating modeling and WBS approaches. The proposed model helps risk analysts select risk response actions that reduce the undesirable deviation from achieving the scope of projects. had put together Integer programming, WBS, and Trade-offs tools to propose analyzing method which combines qualitative analysis and quantitative model to select the optimal risk response strategies. A network-structured framework that confronts the multidimensional nature of project risks and responds to highly prioritized risks was presented by (Samadi et al., 2014) using tools such as Information Technology Outsourcing (ITO), fuzzy ANP, and fuzzy TOPSIS.
To understand the optimization of risk reduction, (Bai et al., 2014) proposed a multi-phase approach. The risk response process in their method was divided into two phases:1) analyzing and determining the actions to reduce the initial risks;2) identifying and analyzing the secondary risks to ensure that secondary risk losses are less than initial risks. (Motaleb and Kishk, 2014) used questionnaire and d statistical analysis to evaluate the relationship between risk response mitigation (reduction, absorption, and transfer) and project management maturity (PMM). The result of the study was a framework to enhance the practical functioning of risk response. An integer linear programming model has been proposed by (Soofifard and Gharib, 2017) to choose appropriate responses for risks. This suggested model has considered the relationships between risk responses, relationships between risks, as well as time and quality constraints. (Naji and Ali, 2017) their study aims to explain and control the uncertainties, identify the reasons for risk response failure, and use optimization methods to choose the strategy to respond to risk successfully. The questionnaire, Gravitational Search Algorithm (GSA), and particle swarm (PSO) were the tools that the researchers used. A quantitative multi-objective risk response method was provided by (Wu et al., 2018), considering the risk correlation among different project sub-processes. The decision-making model was proposed to assist the project managers in selecting the optimal risk responses that minimize the total expected losses, delays, and quality reduction by using In sum, all the above previous studies have made considerable contributions to the understanding and the execution of project risk management in general and the risk response phase in particular, which will facilitate the decision-making process and lead to achieving the objectives of construction projects.

CLASSIFICATION OF REVIEW
The previous studies can be classified into different categories based on the process, approach, and research methodology used by researchers, as illustrated in

CONCLUSIONS
Although most of the research papers have discussed risk management and focused especially on risk identification and assessment. This study has focused on reviewing works of literature related to the risk response stage with the fulfillment of all objectives of projects. To achieve the aim of this research, the concepts of risk, risk management in general, and risk response in specific were reviewed. This study suggests that six steps could outline risk management: 1) Planning 2) Data collection and risk identification 3) Evaluation of risks quantitatively and qualitatively 4) Developing a risk response plan 5) Evaluation and implementation 6) Monitoring and control. The risk response literature showed two important points:  Risk response is a crucial phase in the risk management process. After the risks have been identified and evaluated, they can be eliminated, reduced, or controlled by choosing the appropriate response to address the risks.  There is an obvious augmentation in the interest in studying the risk response stage.
Therefore, this study concludes and emphasizes that risk response should be considered an essential activity to complete the risk management process to execute project activities successfully, which will lead to achieving the objectives of projects, minimizing the losses due to risks, and maximizing the benefits due to opportunities. As indicated in the literature review, a new research direction has opened. This study recommends proposing more detailed research papers to address the problems of planning, selecting, evaluating, implementing, controlling, or monitoring risk response phases during different situations, such as presenting a study about responding to risk:  According to the perspective of each project party (owner, contractor, engineer, etc.)