Construction Process Improvement for a Mass Housing Project: A Case of Pre-cast Housing Construction

Timely completion at minimum cost satisfying quality requirements and specifications is the main objective of any construction project. However, these achievements becomes much more crucial in case of housing projects, partly because of demand of the client, for selling a product in this competitive market, the houses should demonstrate sound quality as well as should be available in time. Residential projects are generally client driven constructions, the demand of client becomes more crucial in case of housing projects. Since the houses are being built on the expense of investors and developers, the retrieving of spent money is important to maintain the cash flow.

Ms. Pratigya Pradhan made a research which particular attempt was to tackle the common management dilemma of housing projects of a newly emerging company in Thailand i.e. to achieve its objective of timely completion of project with satisfactory quality to be offered to the client. The major management dilemma is that the project is failing to achieve the schedule target as demanded by client and buildings are suffering quality problems which cause low satisfaction of client and ultimately direct or indirect loss to the company. Project is behind the schedule and displaying low quality products.

The major objective of Ms. Pradhan’s thesis is identification of factors causing delay and quality degradation in projects and propose construction process improvement in order to improve the quality and shorten the schedule. In order to achieve the major objective, the following sub-objectives were formulated.

1. Identification of managerial delay factors, its frequency of occurrence, impact on delay and impact on quality by assessing the perception of site personnel; Managers and foremen.

2. Conducting construction process diagnosis to study the work process and workers productivity, safety provisions during operations in order to identify the underlying operational factors causing delay and quality degradation in activities and their sequencing.

3. Finally, to propose construction process improvement in order to minimize the hindrances in achieving time and quality target.

Conclusion

The observation conclusions presented in this part, consists of summary from periodic observations and discussions and questionnaire survey with project manager, site engineers, foremen and quality control department including yard persons.

1. Identification of managerial delay factors (its frequency of occurrence, impact on delay and impact on quality)

The managerial factors, defined as the factors affecting overall project performance, were finalized by the literature review and informal interview and enlisted in the questionnaire and ranked by site personnel broadly categorized as managers and foremen, from nine different sites of the same company. As per the data analysis i.e. observation of mean value and hypothesis testing for frequency of occurrence, impact on delay and impact on quality as ranked by site personnel following conclusion can be drawn regarding problems affecting overall project.

a. Manpower Problem is the major problematic area which has greater impact on delay and quality of the project. It also includes four major problems such as: (a) lack of manpower, (b) crew absenteeism as the major one, (c) unskilled manpower and (d) lack of supervision as the other problems.

b. Material Problem is another major aspect of problem. The unavailability of material had major impact on delay, and problem in quality of material had greater impact on quality problem in the project. Both problems had high frequency of occurrence in the project. However, the major problem affecting the quality was ranked to be quality problem in material. The reason for late delivery of material was answered as a supplier fault due to high market demand; however the long procedure of the purchasing order from head office was complained

c. Problem in Co-ordination was ranked third problematic area as evident from structured questionnaire results. Problem between sub-contractors was basically occurring in one individual house between structure and finishing works. Problem in co-ordination rarely exist between the sub-contractors of activities of one group because each group i.e. structure and finishing were handled by one foreman so he normally handles the relating problems swiftly. However, the problem of co-ordination between the subcontractors of structure occurs with that of finishing. Normally due to carelessness of the structure workers, finishing workers have to suffer the problems such as holes, grooves and bolts left, uneven surfaces, creating problem in finishing work thus resulting to conflicts and delay in amending the faults and also quality problem in some cases such as leakage and smoothness in surface.

d. Problem in design was ranked to be moderately occurring in site. While inquired, the changes in specification of finishing works occurred moderately.

e. Financial Problem occurred moderately in the site, inadequate financial problem was ranked by foremen more than that of manager and cost overrun was ranked more by managers. When asked it was said that although the company do not much compromise in the financial supply, due to cost overrun on site, sometime there is inadequate supply to foremen level. Normally, subcontractors extend activities work to few days more, due to delay in payment. As per the direct labor (about 30%) hired in site result to more crew absenteeism than subcontractor as they only consider the daily payment and take less care of completion of the work since payment doesn’t depend upon work quality and completion.

f. Problem in equipment or shortage of equipment was rarely experienced. To reinforce the construction process and increase the target of accomplishment, equipment was readily supplied in the site with very few cases of damage and delay due to repair situation. Also evident from survey results the frequency of occurrence, impact on delay and impact on quality due to this problem is quite low.

g. Problem due to site accidents were quite less. The safety checklists show the satisfactory condition of safety provision except in some cases like not enough scaffolding provision, carelessness of the workers especially in roof tiling. The frequency of occurrence, impact on delay and impact on quality on project are quite low due to this problem.

In addition to observing the overall mean values of the attributes; frequency of occurrence, impact on delay and impact on quality, of a particular problem, the variation in view points of managers and foremen regarding a particular attribute of a problem was also compared. The comparison results shows that the significant difference in opinion was found in very few problems, in most of the cases slight difference in opinion was found.

3. Identification of Operational factors (Conducting construction process diagnosis to study the work process and workers productivity, safety provisions) in order to identify the underlying operational factors causing delay and quality degradation in activities and their sequencing

Major operational Problems in Activities

a. Structure works

For casting panels, the schedule for delivery is given to the yard by the site office before hand in order to get the material (pre-cast piles) on time. But the yard fail to meet this target, in such case sometime the stock pre-cast elements are also not enough and the schedule of that building is delayed.

The major delay was identified in installation of panels to set house, typically characterized by rejection of panels- 5%, panels not fitting – ( about 30% cases)and adjustment to be made on site showing low productivity material not ready- 2%, poor workmanship and crew absenteeism.

Other reasons of delay are late delivery of material from pre-cast yard and steel roof, unavailability of transportation for material and turnover. The cases of equipment damage are very rare.

b. Finishing Works

The major factors causing delay in finishing works is because of insufficient labor in major items like cement finishing and flooring, unavailability, late delivery or insufficient delivery of material, Poor workmanship of labor in sanitary fittings and painting;- major reason for disapproval by client. The reason for late delivery of material was answered as a supplier fault due to high market demand; however the long procedure of purchasing order from head office was also complained.

c. Work Sampling Results

As per the assessment of productivity of a gang work by several periodic observations the following facts were observed:

- The productivity rate of the group of workers were found to be varied by the type of work of activities, number of obstructions in construction process , time of the day and also from one group of worker to another group in same activity as well.

- The productive percentage is is high up to 50 % in early morning hours, diminishes after 2-3 hours ie need a sort of cigarette break and lowers down up to 20% productive percentage of labors in midday sun time and boosts up to 35 % in late hours.

- Certain gangs of workers are found to be more productive than other even for same construction activity. However, there is no solid system to compare progress to subcontractor level so as to compare or encourage them for productive works.

Whenever, there is some delay factors occurring there is direct impact on productivity as well, such as panels not fitting exactly, material not arriving at time, some person engaged in welding and next process has not started. So workers take cigarette breaks or a small nap until the problem is solved.


3. Construction Process Improvement

“Labor output is considered beyond control, other than the journeyman”, Picard 2003. Experience shows that the construction work process can be improved significantly by simply reducing or eliminating factors that interfere with crafts and technicians, and contribute to variability while diminishing the level of performance. As such after summarizing the major and minor delay factors underlying in the construction process, following recommendations are proposed.

a. Improvement in Managerial Aspects

- Proper planning of crew should be done before admitting considering the unavailability of labor in harvesting season.
- Enhance communication with head office especially for material ordering and change in design
- Strengthen quality control by increasing number of supervising staff.
- Since prefabrication is new technology for unskilled labor from farming based background.
- Proper provision of training the labor should be done.
- Change material to the available one
Some of the materials need special order that is ordering from abroad such as there is risk in ordering timely delivery as well as quality problem.
- Develop Penalty System to the supplier for late delivery

b. Improvement in Construction Process and on site Activities

Scheduling and work sequence

1. Presently, the prefabrication (2 days) and installation ( 3 days) of steel roofing are done serially after the set house. (Refer to Steel roofing, Table 2).Prefabrication of steel roof can be done previously before the set house is complete; this enables reduction of 2 days in critical path in structure works.

2. Since its clear from CPM of finishing works ( Chart1) that parqueting work (lying in the critical path) takes a significantly long time i.e. 10-15 days (3 days for installation and rest 80% of time in drying of the glue for parqueting works) which is almost 20-33% of overall schedule. Use of parqueting as a finishing work also needs to be re-evaluated, in order to shorten the schedule.

3. Proper co-ordination between site office and yard to ensure the casting. Increasing supervision in some of the activities such as set house and sanitary fitting is to be provided. Due attention should be drawn in casting schedule and quality of the panels to avoid breaking or rejection of panels which delays the setting house activity and the finishing works in

Productivity of Worker

- Increase the target in first four months of a year, so as to utilize labor availability.
- A motivation strategy can be developed to increase the efficiency of the labor on site such as comparisons of one gang work with another, incentive system and quality circle.

Conversion of cast in situ to pre-cast

- Footing for fence can be pre-cast.
- Outer door window frame can come with the pre-cast panels. The time taken to fill the gaps by mortar is reduced.

His thesis abstract is copied and posted.

Abstract

An important measure of success in the management of construction projects is the achievement of project within the prescribed time scale. Although the importance of time is realized, many projects fail to achieve them. Specially, in client driven projects like mass housing where maintaining quality and in schedule is the major issue, this challenge becomes more prominent.

The major objective of this thesis is to shorten the time and improve the quality in housing projects. The first step was to identify the factors causing delay and quality degradation. Structured questionnaire were administered in nine of the sites with same organizational systems and building types but varying in the scale. Fifteen problems grouped in seven categories of problematic areas were ranked from 36 respondents from Managerial level (including project managers and site engineers) and 54 respondents from foremen level. Each of the problems was ranked regarding frequency of occurrence, it impact on delay and impact on quality on the project. Two hypotheses were formulated to detect the perception of a particular problem in delay of a project and quality problem in the project considering the difference in perception of managers and foremen.

In order to detect the operational problems regarding detail sequence of works and other detail problems during the construction, construction process diagnosis was performed for detail activities for a particular building type (most commonly constructed) in a selected site having greatest investments among the sites. These basically include the process and sequence study of work along with the time study, labor and equipment information were collected for each of the activities. During the study observations reinforced by informal interview, observations were made in order to determine the major and minor delay factors. Further, work sampling of the selected activities of work packages, were performed for four different period of time of a day i.e. early morning, late morning, afternoon and evening, the number of samples being collected in average 340 activities and 930 for overall construction scenario.

The results showed that the most problematic issues affecting delay as well as quality degradation were problem in manpower and that in material. Problem in co-ordination and finance also had moderate impact on the delay and quality degradation of the project.
Finally, suggestions for construction process improvement were proposed in terms of management level and improvement on construction process and on-site activities and their sequencing.