Success Factors and Barriers of Last Planner System Implementation in the Gaza Strip Construction Industry

RESEARCH ARTICLE Success Factors and Barriers of Last Planner System Implementation in the Gaza Strip Construction Industry Bassam A. Tayeh, Khalid Al Hallaq, Abdulla H. Al Faqawi, Wesam S. Alaloul and Soo Y. Kim Civil Engineering Department, Faculty of Engineering, Islamic University of Gaza, Gaza, Palestine Department of Civil and Environmental Engineering, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 32610 Tronoh, Perak, Malaysia Department of Civil Engineering, Pukyong National University, 45 Yongso-ro, Nam-gu, Busan, 48513, South Korea


INTRODUCTION
The construction industry is influenced by a number of issues, which necessity to be explained and addressed [1].The chronic problems of construction projects poor performance are low productivity, risk, defective design, inferior working conditions, and insufficient quality etc. [2,3].Unfortunately, these chronic problems have created a large wastes volume, which the owner, in reality, is paying as a part of the project budget [4].The construction industry is known to be one of the largest environmental polluters, physical waste producers, and energy consumers throughout its lifecycle.Because of these challenges in the built environment, including issues relating to rapidly growing populations and anthropogenic climate changes, there is an important need in proceeding the industry towards sustainable development.Therefore, lean construction approach was transformed from the car manufacturing industry into the construction industry to reduce the waste and optimize the resources.Lean construction is a mixture of operational research and practical development in design and construction with an adjustment of lean manufacturing philosophies and practices to the end-to-end design and construction procedure.Dissimilar manufacturing industry, the construction industry is a project-based production procedure.Lean construction is worried about the alignment and holistic pursuit of concurrent and continuous enhancements in all measurements of the built and natural environment: design, construction, repairs, retrieving and reprocessing [5].One of the lean construction tools is Last Planer Concept (LPC), which usually applied to cover the project planning and scheduling procedure.Therefore, this proves to be a perfect method in dealing with waste minimization and efficiency improvement by the analysis of the per cent of planned complete.The important role of the last planner concept is to replace optimistic planning with realistic planning by assessing the performance of workers based on their capability to reliably achieve their promises.The aim of the last planner is to pull the tasks by reverse phase scheduling through team planning that optimize the project resources.
The construction sector in Gaza strip had a major development and significant growth in the aftermath of 1994, after the Palestinian Authority establishment [6].It suffers from several problems such as overruns in time and budget, low productivity, insufficient coordination, poor quality, and high accident rates etc. [7,8].[9] stated that the industry needs major attempts at growing awareness of the modern management approaches among its stakeholders.Educating the operators of the construction industry is vital to consolidate the quality culture and wastes reduction.It also needs a proper national campaign to capitalize on its strengths and the potential improvement opportunity [10].The industry can be motorized by initiative programs that include firm technical assistance, access to finance access to technology, workforce development, and policy and regulatory reform [11].
This paper investigates the LPC success factors and barriers in Gaza Strip construction industry.The results draw the roadmap for this concept proper implementation in order to address the poor performance problem in Gaza strip construction industry.

LITERATURE REVIEW
lean thinking concepts have evolved and were successfully implemented by Toyota Motor Company since the 1950s.The system has two main concepts: Just in Time flow (JIT) and Autonomation (smooth mechanization).Implementing lean concepts means applying tools and techniques throughout the stages of a project lifecycle in order to minimize waste and enhance productivity.A hypothetical foundation is given through the transformation flow-value aspect and further aspects of management theory and complexity theory.Apparently, however, adopting lean concepts need an essential adjustment of classical structures in terms of both organisation and behaviour.

Principle of the Last Planner Concept
The Last Planner Concept (LPC) is an applied technique in which construction executives and crew leaders cooperate with each other to arrange work plans.The outcome work plans will be executed with a high level of reliability, therefore enhancing work constancy and expectedness [12].In other words, the LPC means works to fulfilment "Coordination by the Plan" [13,14].This concept was established by Ballard and Howell as a production planning and control scheme to help in levelling changes in construction workflow, emerging scheduling foresight, and decreasing ambiguity in construction processes [15] Porwal [16] explained that the main principles of the LPC are: Identify activities are planned with more details to accomplish the work; Identify plans cooperatively with those who are to execute them; Identify and eliminate restrictions on planned activities as a crew; Create and secure consistent promises; and take future lessons from failures to prevent future reoccurrence.While, the functions of LPC are: "Cooperative planning; Making Ready by constraints identification and removal, Task breakdown, Operations design.Releasing; Obligation; and Learning".
The functions of the LPC also consist of the productive section and workflow management and affecting quality tasks.Moreover, the purpose of the LPC is to make the work simpler to understand the root causes of the issues, and to take suitable decisions concerning action needed during the construction process in order to bring the project back to the baseline; thereby enhance the performance [17].
The LPC consists of many effective techniques such as improved visualization, 5S procedure, regular huddle meeting, first run study, fail-safe for quality, value stream mapping afford working planning to optimize the cost and time by maintaining the intense pressure for construction on every task [18].The LPC is a methodology designed to minimize plan failures and to avoid unnecessary execution failures [19,20] stated that LPC provides all of the following: A work scheme of what must be done, An organization map-who-does-what, An agreement among parts of work -when to start and when to finish, A strategic plan-when we need to prepare materials, trade teams, drawings etc., A device for workflow monitoring, and A basis for control progress.The LPC consists of five fundamental integrated components [21], as shown in Table 1

Phase Planning
This stage is used to divide the master plan into different stages to improve further detailed and information work plans and supply objectives that could be deliberated as targets by the project manager.
▪ Shape work plan features in the best achievable details and rate for satisfying project objectives within the power of the organization in time.

Look Ahead Planning
This stage is used to focus management awareness on what is assumed to occur concurrently in the future and to motivate actions in the current time that required future.It represents a transitional phase of planning.This timetable covers key work elements that should be accomplished to achieve the milestone times in the main pull schedule.
▪ Mapping manpower and other resources with workflow, ▪ Harvest a backlog of tasks for frontline crew superintendent screened for design and finishing of the predefined work, ▪ Assemble interdependent tasks together, thus the work statement planned for entire procedure jointly by multiple trades.

Weekly Work Plan (WWP)
This stage concern is to make production tasks cooperative arrangement for the succeeding day or week thru weekly meetings.The WWP meeting includes the weekly plans, safety concerns, quality issue, resources, construction techniques, and any posable problems.
▪ Recognize real actions and check their feasibility earlier to task execution so as to shield construction units from ambiguity.▪ Optimize the use of the construction unit's capability and recognize individual's differences based on the timetable loads.

Percent Plan Completed (PPC)
In this stage, the project planning is improved by continual valuation and knowledge from breakdown.The PPC is the degree of the proportion of potentials made that are provided on time.The PPC can be computed as the number of tasks that are finished as planned divided by the total number of planned tasks, and it is shown as a percentage.
▪ Assist in the incessant enhancement of the construction project as efforts are made to avoid the reoccurrence of issues.▪ Determine the reasons for the nonachievement of tasks immediately during analysing PPC.

Critical Success Factors (CSFs) for Implementation LPC
There is a substantial body of literature concerning the use of LPS for various construction projects.The majority of this literature is in the form of case studies from academic and industrial backgrounds.Case studies report the use of LPS in different project settings (building construction, heavy civil construction, etc.), in different parts of the world, and for different project phases (definition, design, pre-design, and construction).In particular, some of them discussed the CSFs for LPC implementation.Table 2 shows a summarized list of the key factors supporting the implementation of LPC in the construction industry from previous studies: The critical factors for successful implementation LPC are the commitment to planning and coordination between the project parties.The collected factors showed that the LPC achieve more successful planning and control than the traditional approach through the involvement of all stakeholders e.g.sub-contractors and suppliers [25].Lacking greater commitment by management on the implementation 16.
There was a lack of integration of subcontractors 17.
Managers lacked participation

Challenges Faced During the Implementation of LPC
Porwal, et al. [26] explained that the LPC challenges fall into two categories: The first category is "challenges faced during the implementation phase" as follows: "(1) Lack of training, (2) Lack of leadership/failure of management commitment or organizational climate, (3) Organizational inertia & resistance to change, (4) Stakeholder support, (5) Contracting and legal issues/contractual structure, and (6) Partial implementation of LPC & late implementation of LPC".The second category is "challenges faced during the use of LPC" as follows "(1) Lack of human capital & Lack of understanding of new system; difficulty making quality assignments/human capital-skills and experience, (2) Lack of commitment to use LPC & attitude toward new system, (3) Bad team chemistry & lack of collaboration, (4) Empowerment of field management or lengthy approval procedure from client and top management, and (5) Physical integration".Dave, et al. [27] said that the barriers emerge through direct observation from organizations practicing LPC.There are several recurrent problems, which can be categorized, as follows: "(1) Inability to effectively deploy collaborative aspects, (2) Partial deployment of LPC, (3) Reduced importance of robust phase and master plans, (4) Missing continuous improvement, and (5) Missing the links between detailed and high level plans [28].explained that the barriers during implementation of LPC are: (1) Misuse of information generated during implementation of LPC, (2) Lack of time and training, (3) Lack of self-criticism, (4) Inadequate administration, (5) Inadequate communication, (6) Inadequate management support, (7) Lack of commitment, (8) Lack of integration of all area, (9) Standards not full suitable, (10) Difficult relationships, and (11) Lack of involvement".
At the same time, the barriers during the implementation of LPC discussed in construction projects within another context are: "(1) Lengthy approval procedure from client and top management, (2) Involvement of so many parties joined the project, especially subcontractors and suppliers, (3) Low understanding of the process planner to the concepts of last planner, (4) Weak communication and transparency among participants of the production process, (5) Lack of integration of the production chain between client, consultant, contractor and supplier, (6) Inadequate administration of the necessary information to generate a "learning cycle" and to take corrective actions, (7) Low implementation of advanced technology in construction, (8) Language and cultural issues when performing a project, (9) Shortage of the training course for the directors when planning and controlling a project, and (10) Over-commitment to the work which can be done in a look ahead plan" [23, 29 -31].Table 3 shows summarized lists for the challenges when implementing LPC in the construction industry from previous studies:

METHODOLOGY
In this paper, a questionnaire survey was conducted to gather the opinions, views, and attitudes of the participants.The questionnaire is the most widely applied method for data collection for both descriptive and inferential surveys.Furthermore, the questionnaire is a fast and simple technique of data collection and more precise when beginning exploring and analyzing the collected data [49].
The targeted population was the construction companies which have valid registration in the Palestinian Contractors Union (PCU) in Gaza Strip and categorized by the national classification committee to have active membership in the PCU until the February 2017.The number of contractors has been recorded and classified according to the work field was 246 companies.For this research target group, there are totally 189 contractors classified under building category only with grades first, second and third classes.The companies under categories fourth and fifth classes were excluded because of the lack of workable and management expertise.

Sample Size and Characteristics
[50] said that sampling is generally executed by recognizing the relative significance of every segment in population and utilizing such weighting to classify them.In order to decide the sample size; the following statistical formula was utilized: Where: SS: The size of sample.Z: Z value (for example: when confidence interval 95%, Z value =1.96).P: Percentage picking a choice, expressed as decimal, (0.50 applied for sample size required).C: Maximum estimation error (0.08).

Correction for finite population is:
The result illustrates that the minimum number of the questionnaires required to be collected is 84, which represent 44.44% of the target group.This research has distributed 110 questionnaires randomly and then received 98 valid responses with 89.01%response rate.

Questionnaire Design and Contents
After making a review of all studies that focus on LPC especially in the construction industry, the questionnaire was prepared to satisfy the research objectives.The questionnaire contained a covering letter that explains the study purpose, the way of filling the questionnaire, the study goal and the confidentiality of the information for encouraging high response, as shown in Appendix A. Sections in the questionnaire were arranged as following: (i) General information about the participant, (ii) Profile of company, (iii) Evaluating key factors (success factors) for applicability of LPC, (iv) Evaluating challenges and barriers of LPC.The Relative Importance Index (RII) method has been extensively applied in construction management studies for determining attitudes with regards to surveyed factors.Numerous studies [10, 51 -58] have used the RII in their analysis.The participants were requested to assess the identified interface problems on a five-point Likert scale between "1" for the strongly disagree and "5" for the strongly agree.Based on the survey response, RII was calculated using the following equation: Relative Importance Index = Where, W is the weighting specified to every factor by the participant between 1 and 5, n1 = number of participants for strongly disagree, n2 = number of participants for disagree, n3 = number of participants for neutral, n4 = number of participants for agree, n5 = number of participants for strongly agree, A is the highest weight (5 in this study) and N is the total number of samples.Regarding the job title results, it is shown that (23) 23.47% of the respondents are head/board member, (29) 29.59% of them are projects manager, (24) 24.49% of them are project manager, (13) 13.27% of them are site engineer and (9) 9.18% of them are office engineer.This indicates that the projects manager is the most persons who face all the crises and he is most of the times available in the sites.For the work experience, it is shown that (31) 31.63% of the respondents have experience less than 5 years, (24) 24.49% of the respondents have experience from 5 years to less than 10 years, (21) 21.43% of the respondents have experience from10 years to less than 15 years, and (22) 22.45% of the respondents have experience more than 15 years.This indicates that the individuals who have experience less than 5 years are the most vigor at work and who don't demand high fees wherefore the contractors mostly required them.

Respondents and Companies Profile
For the companies' profile, Table 5 shows the results of the questions about the company age (years), company size (according to the number of permanent employees), Capital of the company, and Number of completed projects worked in during last five years.The results confirm more that 60.020% (59) from the sample have company age more than 15 years.This indicates reliable results.However, in term of company size, it is shown that (2) 2.04% of surveyed companies is very small companies, (61) 62.24% of them small companies, (26) 26.53% from the surveyed sample is medium companies, and (9) 9.18% of them is large companies.This indicates the companies at Gaza strip have few permanent employees while the majorities have non-permanent employee.
Regarding the Capital of the company, it is shown that (15) 15.31% from the sample have capital Less than $100,000, (21) 21.43% from the sample have capital from $ 100,000 to $250,000, ( 27) 27.55% from the sample have capital from $251,000 to $500,000 and (35) 35.71% from the sample have capital more than $ 500,000.This indicates that the size of Gaza strip construction projects is comparatively small.Regarding the company work volume, it is shown that (11) 11.22% from the companies sample have number of completed projects worked in during last five years from 1 to 5 projects, (21) 21.43% from the companies sample have number of completed projects worked in during last five years from 6 to 10 projects, (43) 43.88% from the companies sample have number of completed projects worked in during last five years from 11 to 15 projects and (23) 23.47% from the companies sample have number of completed projects worked in during last five years more than 15 projects.This indicates that the projects which have been started in the same period were high, and the number of projects is small in comparison to the number of companies in the Gaza.But the companies in the market cannot have more than one project in the same time because of the shortage of capitals.

Evaluating the Key Factors Supporting for Success the LPC
The mean, RII, and t-test were calculated for each factor as presented in Table 6.Based on Table 6 results, it is shown that "close relationship with subcontractors" factor is ranked in the first position with a mean of 4.05, RII of 81.02% and P-value of 0.00.This result explains that implementing LPC require high cooperation and robust relationship between the subcontractors and the top management.The obtained results agreed with [24] who highlighted that coordination issues with subcontractors may cause interface issues in sequences of activities and delay in the completing the tasks on time.Also based on Table 6, it is presented that "top management support " factor scored the second order with a mean of 4.03, RII of 80.61% and P-value of 0.00.This indicates that implementing LPC require support and commitment of top management.The achieved outcomes agreed with [23] who highlighted that the presence of complete support and obligation from top management is necessary."Coordination and cooperation between staffs to achieve teamwork" factor scored the third order with a mean of 3.94, RII of 78.77% and P-value of 0.00.This result shows that huge cooperation and robust relationship between the staffs themselves and the top management is necessary.The effective team building will support the LPC and achieve satisfactory performance indicators.The obtained outcomes in the same line with [23] who highlighted that the existence of coordination and cooperation between staffs helps to achieve team work and leads to the success of the project."Motivate employees to make a change" and "willingness to learn and train" do not have high influence on the implementation of LPC.The first factor is ranked in the position 16 with a mean of 2.84, RII of 56.73% and P-value of 0.00 while the second factor is ranked in the last important position with a mean of 2.82, RII of 56.32% and P-value of 0.00.These results confirm that implementing LPC still needs massive attempts to change the mentality and culture of the parties operating in Gaza Strip construction industry.The results do not match with [23] who found that "motivate employees to make a change" is important factor to implement LPC and do not match with [24] who found that "willingness to learn and train" will be useful to implement LPC.This may relate to unwillingness to self-development through learning and training and may relate to resistance to change.
The overall results show that the average mean is equal to 3.56, RII is equal to 71.28% which is larger than " 60%", the value of t-test is equivalent to 4.372 which is larger than the critical value of 1.99, and the p-value equal 0.000 which is less than 0.05.These indicate that key factors for applicability of LPC are significant at the level of 0.05.

Evaluating the Challenges/Barriers of LPC
Table 7 shows that "lack of skills, training, and experience" and "lack of the training program for the managers" related to the challenges/barriers of LPC implementation are ranked in the first position with a mean of 4.13, RII of 82.65% and P-value of 0.00.Actually, this is a critical fact in the Gaza Strip since any training for the managers and staffs (subordinates and labours) needs extra resources (cost and time) while the contractors are not ready to overcome this barrier.The majority of the believe that they can invest better in construction process itself instead of training the staff.These outcomes agreed with [59] who highlighted that any company needed training programs for staffs and highlight the importance of skill development and human capital in using LPC.Also according to Table 7, it is shown that "lengthy approval procedure from the client and top management" and "misuse of information generated during implementation of LPC" are categorized in the third rank with a mean of 4.11, RII of 82.24% and P-value of 0.00.Actually, long-lasting endorsement process from the client and highest management is one of the utmost fumes obstacles in arrangement and monitoring construction projects in the Gaza Strip.Therefore, if any delay occurs during construction stage the owner should be in charge of damages instigated by this interruption.In addition, misuse of information generated during implementation of LPC would affect the corrective actions to improve the accomplishment rate.These two barriers were introduced by [59,60].
Critical value of t at df "97" and significance level 0.05 equal 1.99Moreover, the respondents did not strongly believe that implementing LPC needs "short-term vision".The result means that the managers and staffs do not allow visualizing issues with sufficient time to take the correct decisions.This barrier is in the last position with a mean of 3.03, RII of 60.61% and P-value of 0.00.
The overall results show that the average mean is equal to 3.76, RII is equal to 75.23% which is larger than 60%, the value of t-test is equivalent to 6.361 which is larger than the critical value of 1.99, and the p-value is equivalent to 0.000 which is less than 0.05.These mean that the challenges/barriers to LPC implementation are significant at the level of 0.05.

CONCLUSION
LPC is one of the lean construction approaches.In this research, a questionnaire survey was implemented to identify the key factors supporting the applicability LPC and to determine its challenges/barriers in the Gaza Strip construction industry.The main results of the study show that: Close relationship with subcontractors, top management support and coordination and cooperation between staffs to achieve teamwork were the key factors of LPC implementation.The high cooperation and robust relationship between the subcontractors, staffs and the top management should be exerted to enhance and develop the LPC implementation.On the other hand, lack of skills, training, and experience, lack of the training program for the managers, lengthy approval procedure from the client and top management, and misuse of information generated during implementation of LPC were the main challenges /barriers of LPC implementation.The intensive training for all parties is in order to enhance and develop the LPC implementation.
It is recommended that contractors ought to comprehend their accountability to Choose the subcontractor based on his previous expertise and competence in light of workers, tools, and equipment as these elements safeguard the obligation of the subcontractor in finalizing the works according to the time schedule.In addition to supporting all parties in the project for the short-term vision to visualize issues with sufficient time to take the correct decisions and achieve the project objectives.

Table 2 . Factors to support the implementation of LPC.
The project does not have all the subcontractors, which forces perform the implementation of LPC through several stages 15.

Table 4
presents the representation of three (3) questions about the respondents; Respondent educational level, Job Title, and Work experience in the construction sector (Years).It is shown that (13) 13.27% of them have educational level diploma, (66) 67.35% of the respondents have educational level bachelors and (19) 19.39% of the respondents have educational level master.This indicates that the willingness of most of the graduates after graduation go to work directly to get workable expertise.