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Productivity Measurement and Analysis Final Report - CIVL 493 AMAC C O N S U L T A N T S THE UNIVERSITY OF BRITISH COLUMBIA - 2004
Productivity Measurement and Analysis Final Report - CIVL 493
AMAC C O N S U L T A N T S
THE UNIVERSITY OF BRITISH COLUMBIA - 2004
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Executive Summary The following report contains the productivity study performed on specific construction processes during construction of the Chancellor House residential project. Chancellor House is a new multi-level, multi-family development located on the edge of The University of British Columbia campus. This document focuses on construction practices associated with formwork installation, concrete pouring, and formwork removal. The objective is to identify areas of improvement or alternative methods that would improve time, cost, quality, and safety performance of the project. As a starting point, the description of activities under investigation is provided and the general observations and various data collection methods are introduced. The data collected is then analyzed using conventional data analysis techniques to measure the productivity of the processes involved. These results are interpreted and recommendations regarding productivity and safety improvement are put forward based on these interpretations. Various areas for improvement have been identified. It was found that there is room for improvement with regards to efficiency within processes such as formwork erection and concrete placing. In some cases the overall crew size could be reduced. Problems regarding fitting the formwork were observed during the site visits and could be attributed to design flaws, lack of detailed drawings form designers, or carelessness of the formwork builders.
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Table of Contents Executive Summary ....................................................................................................i List of Illustrations .................................................................................................... iii 1.0 Introduction.........................................................................................................1 2.0 Project Site Description ........................................................................................2 3.0 Work Details ........................................................................................................3
3.1 Activity of Interest ............................................................................................3 3.2 Observations ....................................................................................................4
3.2.1 General Observations..................................................................................4 3.2.2 Work Sampling...........................................................................................5 3.2.3 Video Techniques .......................................................................................6 3.2.4 Site Safety .................................................................................................6 3.2.5 Environmental ............................................................................................7
3.3 Data Analysis....................................................................................................8 3.3.1 Cycle Chart ................................................................................................8 3.3.2 Crew Balance Chart ..................................................................................12 3.3.3 Labour Utilization......................................................................................15
3.4 Discussion ......................................................................................................16 3.5 Recommendations ..........................................................................................16
4.0 Conclusion.........................................................................................................18 5.0 Acknowledgements ............................................................................................19 Appendix A. Site Observation Tables .........................................................................20 Appendix B. Cycle Charts – Expected Results.............................................................28 Appendix C. Crew Balance Charts .............................................................................30 Appendix D. Project Decision Table...........................................................................33 Appendix E. Labour Utilization Calculations................................................................34
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List of Illustrations Figure 1. Arrangement of formwork corner piece. ........................................................5 Figure 2. Formwork installation cycle chart..................................................................9 Figure 3. Concrete pour cycle chart...........................................................................11 Figure 4. Formwork removal sequence......................................................................12 Figure 5. Panel installation balance chart...................................................................13 Figure 6. Formwork removal balance chart ................................................................14 Figure 7. Concrete Pour Balance Chart ......................................................................15
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1.0 Introduction This report will investigate the productivity of construction methods involved in formwork installation, concrete placement, and formwork removal. This investigation was carried out for the Chancellor House construction project at The University of British Columbia (UBC). After visiting various construction sites on campus and interviewing site personnel, the Chancellor House site was chosen for the purposes of this research. This site was chosen due to its highly visible layout, the suitable work schedule, and positive management response. The following sections will provide a general project overview followed by a detailed description of the activities under observation. Data collection techniques and various methods of data analysis are discussed in the later sections. A comprehensive analysis of productivity of the specified operations is then conducted and various areas of improvement regarding productivity and safety are identified.
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2.0 Project Site Description The University of British Columbia (UBC) is currently being swarmed by construction crews. On practically every end of campus there is a construction project. Various facilities such as the new staff and faculty homes, a new life sciences research building, an extension of two of the primary engineering buildings, a new genome lab, and multiple other new housing structures including the Chancellor House are currently under construction. The Chancellor House is a new multi-level, multi-family development located on the edge of the UBC campus. Located at 1715 Theology Mall on the south side of North-West Marine Drive, residents will be able to capture breathtaking views of the ocean and coastal mountains while basking in superbly designed interiors and having the option to go for a stole along the boulevard at a moments notice. There are numerous reasons why the Chancellor House will be a successful development one of which are the major players involved with the project. UBC Properties has done a great job of selecting Ramsay Warden Architects Ltd to design the building and Intracorp Developments to bring it to life. Intracorp is focussed on residential communities and for over 25 years has been involved in projects across BC, Alberta, and Ontario. For this project CitiWest Structures was selected as the designer. This $35 million structure is primarily concrete and includes numerous columns spread throughout. Construction at the site began in December of 2003. Since that time the excavation has been completed and the foundation and basement floor have been poured. Currently, the third floor structure is under construction. February 2005 is the intended occupancy date. Besides the general information of the project and the structure, the layout of the construction site itself is very important. Arriving at the site one of the first observations made was the centrally located tower crane. The location and size of the crane allows it to reach anywhere on the site. There are two main access points into the site although only one is ever used because of it ease of access for deliveries and relevant location to other parts of the site. Located directly along side the construction of the building and across from the main entrance just mentioned are the lunchroom, main offices, and first-aid trailer. Restrooms were provided directly within the project site and not forced to the outer, fenced perimeter. There are two main rows of storage pilings along two sides of the square inner perimeter of the project site.
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3.0 Work Details This section of the report will focus on describing the objectives of this project, which entail the study of construction techniques and discussions with site personnel regarding these techniques. As a starting point, the description of activities under investigation is provided and the general observations and various data collection methods are introduced. The data collected is then analyzed using conventional data analysis techniques to measure the productivity of the processes involved. These results are interpreted and recommendations regarding productivity and safety improvement are put forward based on these interpretations.
3.1 Activity of Interest In order to obtain sufficient observations of a particular activity and determine the productivity associated with it requires selecting an activity of interest that is repetitive and lasts between 10 minutes and 2 hours. Discussing possible options with the site supervisor it was determined that at the current stage of the project, collecting data and observations related to formwork would be an excellent focus. With this being a concrete structure, formwork was to be used extensively for this project. The design of the building called for numerous walls and columns that varied in size and complexity. After being directed to the formwork foreman, Mr. Tom Nowak with CitiWest Structures welcomed us onto the site and discussed with us the processes that are involved with formwork. Out of this meeting came the determination to focus our attention on formwork installation, concrete pouring, and formwork removal. Formwork is used to create a barrier or perimeter and can be arranged in a variety of sizes and shapes. Typically made of wood but increasingly made of plastic, formwork is used to form concrete elements. Pieces of formwork are brought together and secured to create a hollow structure with a smooth, interior face. Concrete is poured inside the structure and allowed to cure. The formwork is then removed leaving the completed concrete element. The process of installation formwork involves seven steps starting with creating the layout for the formwork. This task requires about 15 minutes and involves marking out the formwork arrangements at a particular location where formwork is to be used. The steel reinforcement cage is then installed followed by installing a series of wooden blocks into the supporting floor at locations specified by the layout. These blocks serve as stops of horizontal movement of the formwork. The first of two form panels is then brought in by the crane, guided by two workers, and held in place while temporary bracing is installed to support it. The crane is then detached and an elevation inspection is performed to identify the level the concrete is to reach during pouring. This procedure lasts approximately 5 minutes. With the crane bringing in the second or close-up form panel, the two panels are braced together, which takes anywhere from 5 to 10 minutes. A final finishing step is performed to seal and gaps at the interfaces of
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the two form panels, to ensure the forms are plumb, and to ensure they have adequate support. Similar details were obtained for pouring concrete into the formwork and removal of the formwork. Appendix B illustrates the sequences for these three major activities. The observations associated with these processed, formwork installation, concrete pouring, and formwork removal, are now presented.
3.2 Observations Various observation techniques were incorporated to study the operations of the constructions site. These include the general site observations, work sampling, and video recording. In addition, site safety and environmental concerns were taken into consideration during the observation sessions.
3.2.1 General Observations
Overall the site was found to be organized and well managed. The construction team seemed to have good team dynamics and interact well with each other. The observations were focused mainly on the installation of wall/column formwork, bracing/tying the formwork, placing rebar, and pouring concrete. Observations were also made on formwork construction and slab/wall rebar placement. It was observed that placing and fastening/bracing the formwork would take approximately 10 minutes with optimal crew size of 3 workers. Many times it would take longer to complete this task and a larger crew size was used. In some occasions, up to six workers would be involved in the erection process which was found to be very inefficient since it would they would take the same amount of time as a 3 person crew to complete the task. It was found that there is room for improvement in the productivity of formwork erection procedure. In a few cases, the formwork would not fit in the designated location and it had to be sawn or cut down to size during which the crane was holding the formwork and was unavailable for other activities during that time. During the resizing activity, a majority of the formwork crew had to wait for the sizing to be completed so they could brace/tie the formwork. Erection and installation of the corner formwork section appeared to be very challenging and time consuming. A large amount of time and effort was spent on fitting/securing the corner piece in place and placing rebar (Figure 1).
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Figure 1. Arrangement of formwork corner piece.
On one occasion the foreman (site engineer) had to stop the work on the section and spend some time reviewing the formwork drawings. This situation seemed to be the cause of a formwork design flaw or a lack of sufficient detail in the original drawings. The formwork surface was cleaned and surface treated before erection which would normally take a long time due to the difficulty with removing older concrete from the surface of plywood. This process would become more efficient if the cleaning is done immediately after stripping the formwork from the new concrete since it has a much lower strength and could be removed with more ease. It was found that a two person crew was responsible for the construction of formwork. Since most of these tasks are interdependent, normally, one worker was busy while the other was waiting for the first to do his part. This task could be ideally carried out by one person considering the inefficiencies present with a two man crew. Installing rebar into slabs seemed to be a long and monotonous process. The workers would occasionally work on it for 10-15 minutes at a time. The slab rebar cage could possibly be prefabricated, similar to column rebar cages, since it consumes large amount of labour time.
3.2.2 Work Sampling Work sampling was done to find the general productivity of the workers on site. For this purpose workers were observed working on various tasks at five-minute intervals. Based on their level of activity for 2.5 minutes these observations were recorded under the following categories:
• "Effective" - worker performs an activity that directly leads to the creation
of the facility. E.g. hammering a nail to secure braces
• "Contributory" - worker is not directly effective but he/she is needed in order for the effective work to take place. E.g. getting tools
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• "Non-contributory" - worker is not doing anything that falls into either of the above two categories. E.g. waiting for others to finish their work
Overall approximately 410 observations are recorded by the three members of AMAC. The first set of data was from five-minute rating that followed a continuous process at a certain location where the task was undertaken. This method allowed for the complete process to be observed. The second set of observations was again a five-minute rating of the same type of activities but in random locations. In this form, depending on the stage of the tasks in different locations, activities were observed in a discrete manner but since the location varied a more general picture of the site productivity could be obtained. The third set of observations was obtained using video recording. The nature of the observations was again every five minutes of a continuous process in addition to tasks preformed in random locations. All this data was recorded in efforts to determine the productivity of each job and is analysed in the next section: Data Analysis.
3.2.3 Video Techniques Video recording was used to gather more detailed information about specific operations. Using a video camera complete tasks were filmed that formed the basis of our cycle charts and balance charts. In addition, some general observations of the site and witnessed problems were noted and are discussed in the general observation section. Furthermore, the video was a good source of collecting 5 minute sampling data since one worker could be observed at a time and the film could be played back as needed. Thus the video was used to verify work sampling, work cycles, and to look for other factors that might be affecting productivity. Although this method was very beneficial it also had its limitations such as restricted field view in time and space: some dependent activities in the cycle could not be shown. Extraction of data from the video recording was a long and time-consuming process.
3.2.4 Site Safety Of greatest concern to the superintendent on this site, and from past experience on any construction site, is fall protection. Not only is this the number one cause of injury and/or death, it is also the most costly. The cost of an accident goes beyond paying for the material or equipment that may have been damaged. When a worker is injured, work stops and not only for the directly affected worker. Bystanders are drawn to the scene to offer help and observe the proceedings. An investigation by the employer is most likely set to follow thereby not allowing work to continue. Current legislation requires that any site where an accident has occurred be investigated by the Workers Compensation Board (WCB) before further work is started. This requirement means greater productivity loses. Of course with the potential loss of an employee, the employer must now alter the work schedule respectively. This could entail
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delaying activities that have a serious impact on the project schedule and/or dealing with hiring new employees. Added to this is the possibility of increased costs associated with increased insurance rates. With fencing installed along the perimeter of the elevated structure and workers wearing the appropriate safety vests, hard hats, and steel-toed boots, it seems that the superintendent was doing a good job at preventing any accidents. No unprotected openings (openings in the floor for instance that could pose the opportunity for a fall) were identified during the site visits. Fencing was installed along the entire perimeter of the site with signs indicating safety guidelines and protective wear placed at various, clearly visible locations along the perimeter and at the dedicated entrances of the site. A first aid station was located adjacent to the field office for easy access and quick assessment of injuries. Traffic was directed by a flag person ensuring control over moving vehicles and workers. For the most part, reflective safety vests were worn by the crew when working on site and harnesses were used to tie workers to the formwork while working on elevated sections. However, some workers ignored this requirement and no discipline of this breach was observed. Other safety concerns observed during the site visits include the lack of wearing protective eyewear while cutting wood or placing concrete. Moreover, occasionally careless conduct was observed during rigging/unhooking the formwork to/from the crane. This includes standing on top of the formwork while the crane was in operation without using harnessing equipment.
3.2.5 Environmental A construction site can make a significant impact on the surrounding area. Dust, noise, pollution, and disturbance of natural habitat are very serious concerns. The design of the site in question was limited by surrounding roads and buildings on all four sides. Due to the size of the structure to be constructed and the size of the lot, it is was most likely not a concern to reduce the footprint of the construction site or something that couldn’t be avoided. It was noted that the layout of the site reduced the space required for storage and equipment thereby unnecessary space was not used however there was not much to begin with either. Most of the vegetation on the construction site was removed and there should be no expectation for otherwise. The nature of the work required a clean environment and accessible environment. Where excavation occurred along a primary side of the site, disturbed and exposed soil was covered with plastic to direct runoff. Any cleaning of concrete equipment, such as the concrete truck, was performed away from sewage drains and on gravelled areas: a controlled method to reduce contamination of the area.
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3.3 Data Analysis To improve the site productivity the collected data had to be analysed. This section of the report provides a detailed productivity analysis using tools such as cycle charts, crew balance charts, and labour utilization and furthermore explores and identifies possible improvement for future discussion with site managers.
3.3.1 Cycle Chart Cycle charts were used to study the complete operation of the process under inspection. This allowed the timing and the sequence of all the steps to be mapped on a chart and relevant relationships of steps to be observed. Furthermore, using the minimum and maximum times of the steps, the most vulnerable (activities that have a cycle time with the highest variance i.e. max – min is the highest) and critical activities in the cycle could be identified and given more attention to find ways of improving the sequence. The first process that was observed was the installation of formwork. This cycle involves everything necessary to construct an enclosed system into which concrete will be poured to create a wall or column. Figure 2 illustrates the entire cycle and includes the minimum, maximum, and average times for each sub-activity associated with formwork installation.
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Figure 2. Formwork installation cycle chart
Min (83 min) Ave (111 min) Max (140 min)
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140
Time (mins)
Finishing
Close-up Panel
Elevation
One Side Panel
Blocks
Layout
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The minimum time observed for the complete cycle was 83 minutes and the maximum time was 140 minutes. Layout, blocks, and finishing of the formwork, which are generally completed independently of the rest of the operation, are included in these values. Upon inspection of this chart, it is easy to observe that the two activities with the maximum difference between the min and max cycles are installation of the first side panel and the installation of the close-up panel. Both activities involve the delivery of panels by crane from the storage area to the desired location and installation. Clearly attention needs to be paid to these sub-activities where careful planning of the crane utilization and design of the formwork are crucial. In a few occasions it was noticed that form panels could not be installed in their intended location thus modifications where required on the fly, which resulted in reduction of effective time and therefore productivity. This type of problem can be associated to design flaws, lack of detailed drawings for form builders, carelessness of the formwork builders, etc. While the occurrence of these types of problems could be reduced, they can’t be eliminated. Thus the actual productivity of the crew had to be looked at to identify other ways to improve productivity of this process. For this purpose balance charts were produced and are discussed in the next section. The cycle chart for this next process shows a complete cycle of all the operations involved in a concrete pour. Included are the initial stages of truck positioning and mixing, which occur once for each delivery of concrete. Depending on the size and complexity of the formwork that is to be filled, multiple bucket runs maybe necessary. The cycle chart includes the overlapping procedures between bucket pouring.
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Figure 3. Concrete pour cycle chart.
0 10 20 30 40 50
Time (mins)
Pour Bucket #2
Position Bucket
Move To New
Vibrate
Reload Bucket
Pour Bucket
Position Bucket
Load Bucket
Truck Mix
Truck Positioning
Min (27 min) Ave (36.5 min) Max (43 min)
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The minimum time for the cycle was 27 minutes and maximum time 43 minutes. The operation was fairly labour intensive and involved the movement of the bucket from one location to another. The activities identified to have the greatest difference between minimum and maximum cycle times are bucket load and bucket pour. Observations from site visits indicate that such time differences are mainly due to handling issues with the heavy concrete bucket. In addition, the involvement of the crane operator in controlling the bucket requires an enormous amount of communication and in some instances problems arose due to miscommunication or misunderstanding between the parties involved.
NEED INTO TO FIGURE
Figure 4. Formwork removal sequence
This chart shows a complete cycle of all the operations involved in formwork removal. The minimum time observed for the complete cycle was 23 minutes and maximum time was 50 minutes. Looking at the chart it is possible to observe that the process seems to be fairly smooth with the maximum and minimum values falling within a reasonable range. However, there is room for improving the productivity of the cycle since the crew might not operate efficiently. This is investigated further in the balance chart section.
3.3.2 Crew Balance Chart
The following balance charts are used to look at the overall productivity of the activities identified in the latter section. The amount of work that each person performed in 15-minute cycles was recorded and used to calculate the overall Labour Utilization Factor (LUF) of the whole operation and in cases where productivity improvements are possible, a new LUF based on the new proposed method was calculated. In the following charts, blue areas indicate effective
0 10 20 30 40 50
Time (mins)
Finishing
RemovalPanel
RemovalHardware
Min (23 min) Ave (41.5 min) Max (50 min)
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work, green indicates contributory work, and grey indicates times of non-productive work.
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Crane FormGuide
FormGuide
HookPerson
Bracer Cleaner Cleaner
Moved Off
Support
Panel
Carry
Moved Off
Watch
Brace Footing
Hold Brace
Guide Form
Wait
Moved Off
Watch
Brace Footing
Hold Brace
Guide Form
Wait
Moved Off
Unhook
AligningPanel
Nail Brace
Help Guides
Wait
Moved Off
Wait
AligningPanel
Nail Brace
Help Guides
Wait
Clean
Wait
Watch
Talk
Clean
Wait
Watch
Talk
Figure 5. Panel installation balance chart
The previous chart corresponds to panel installation for formwork. As shown, most of the workers do a fair amount of productive work. In many cases where workers were classified as contributory when they were waiting or watching because their presence was required during subsequent stages in next sequence. However, observing the last two workers who were responsible for cleaning after the formwork was done and preparing the ground for the next layout, it is easy to see that they have a long period of non-productive work when they are either talking, waiting, or watching. This was mainly due to lack of supervision and lack of direction or motivation. Along with being unproductive, these individuals were also distracting to other working labourers and thus the overall productivity of the area is affected in two ways. Rearranging the sequence of tasks that these two workers follow should result in significant gains in terms of productivity.
The following balance chart shows the productivity level of the workers associated with the formwork removal process.
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0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Crane FormDetacher
BoltRemover
HookPerson
Cleaner
Clean
Wait
Watch
Moved Off
Support
Panel
Move Span
Lift Panel
Moved Off
Separate Panel
Wait
W t h
GuidePanel
Moved Off
Separate Panel
Wait
W t h
Watch
Moved Off
Separate Panel
Hook Panel
W it
GuidePanel
Figure 6. Formwork removal balance chart
In this case, it is easy to observe the fact that the Bolt Remover is only productive 30% of the time. His/her job is separating panels, of which two other workers have expertise with. Thus if the job of this unproductive worker can be divided among the Form Detacher and the Hook Person, the total man hours required can decrease by 15 minutes (20%) and the amount of productive work performed by the other two workers with increase by 15% each. However, this may increase the total amount of time required for the process, but the overall productivity of the cycle will increase from LUF0.25 = 51% to LUF0.25 = 66%. Thus eliminating the Bolt Remover and distributing his work to others can be beneficial to this process. Finally, the workers associated with concrete pouring are considered. Although there are many wait and watch (see non-productive work) periods in this cycle, the work is being done between two distinct locations: at the concrete truck and at the formwork. With this arrangement one crew must wait for the other before proceeding with their specific duties: the crew on the wall doesn’t have much to do except vibrate, which only lasts so long, between receiving loads of concrete. It is therefore expected to witness non-productive periods. However, it was decided that the necessary waits should not be regarded as completely non-productive work. Instead a factor similar to the 0.25 contributory factors can be used to account for the waits as somewhat effective. For example, if we assign a 0.35 effective factor for the wait times, then our LUF value for the 15-minute cycle would be 58.5% (calculations are included in Appendix E).
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Figure 7. Concrete Pour Balance Chart
Through inspection of the balance charts, the performance of individual workers has been analysed. This is a very narrow view of certain aspects of the project. A more general or broad view of the project operations is dealt with in the following section.
3.3.3 Labour Utilization
Labour Utilization Factor is a basic measure of the relative effective work time of the operation. In this study the results from the 5-minute rating observations were used as the random samples since more accurate observations regarding the effective, contributory, or non-effective nature work could be made during this period of time. The results are presented below.
TimeWorkTotalTimeWorkryContributoTimeWorkEffectiveLUF )25.0( ×+
=
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Crane Rigger@
Truck
BucketGuide
BucketGuide
BucketOpener
Vibrator Truckdriver
Wait
Vibrate
Vibrate
Vibrate
Riging
Wait
wait
Hold
Rig
Guide
Carry Hold BucketPouring
Carry Bucket
Move Span
Support Bucket(Grnd)
Hold Bcuket Pouring
Support Bucket(Grnd)
Guide Pour
Guide Pour
wait
Wait
Mix
wait
Mixing
Rigin
Rig
Guide Pour
Guide Pour
wait
Wait
Guide Pour
Guide Pour
wait
Wait
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Table 1. Labour Utilization Calculation
Number of Observations Effective Contributory Non-Contributory Day 1 66 78 17 Day 2 55 36 20 Day 3 57 44 33 Sum 178 158 70 LUF (25) 53.6% LUF (100) 82.4%
Although the values are very close, there are some variations which can be related to environmental and weather condition, day of the week, type of the work performed, number of crews involved, and observer’s method of rating in each day. The Labour utilization factor using the 25% factor for contributory work is 53.57%. It should be noted that this number is somewhat conservative given the nature of data collection regarding contributory work. If the 25% factor is not taken into account the LUF becomes 82.4%: a very good rating.
3.4 Discussion Due to the busy nature of construction, the occurrence of unexpected situations, and the timeframe allotted for this project, arrangements for a summary discussion meeting with the formwork foreman were very difficult to make and eventually fell through. The purposes of this meeting was to review the observations that were obtained, work through the creation of the cycle and balance charts, explain the determination of the labour utilization, present our recommendations, and obtain some feedback of our work. AMAC plans to hold this meeting in the future even though the minutes of which will not make it onto this report.
3.5 Recommendations It was found that productivity improvements could be made to the formwork erection and securing process. Therefore, more attention should be directed towards the duration of these processes. Constructability was found to be an important delay factor during the erection process and it should be taken into consideration when designing the formwork. Some delays were due to problems with fitting of the formwork panels into their designated locations. Perhaps more thorough pre-screening of drawings and spotting could help in eliminating some of these delays. Clean-up of the formwork surface, removing any concrete that had adhered it self to the surface, was performed directly before erection. Less time could be spent on the clean up process if it is carried out directly after stripping since concrete has a lower strength at that point. Installing rebar into slabs was found to be long and monotonous process. Similar to column rebar cages, there might be some merit in investigating whether the slab rebar cages could be prefabricated in the rebar storage section of the site.
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As mentioned, for the majority of the time that AMAC was onsite, safety regulations were followed quite well, however some non-conformance was observed regarding lack of connecting harnessed and wearing protective eyewear. During a concrete pour there were three workers at the top of the formwork and one or two below. Of the two below, one worker was responsible for operating the latch that controlled the flow of concrete. Another worker was sometimes seen stabilizing the ladder required for the latch operator to reach the latch, even with the latching extension pole. A recommendation would be to invest in an adjustable latching pole and save the time and expense of having the one worker holding the ladder: this worker could be used elsewhere on the site. Of the minimum three workers that were atop the form, two were seen guiding the crane bucket and inspecting the level of concrete in the form. The third worker was responsible for vibrating the concrete. Although it might be necessary to have the second guide in windy environments, on a calm day his presence seemed unnecessary. Although requiring a different style of bucket, it seems possible that the worker guiding the bucket and eyeballing the concrete level could operate the bucket latch. It was noted that the operation of the bucket that was used was quite crude and jammed at times thereby limiting the control over the amount of concrete dispensed.
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4.0 Conclusion By studying the operations at of the construction of Chancellor House, the productivity of the crew can be determined and therefore the efficiency of the project is determined. First, general observations were made about the design and layout of the site. Simply based on these preliminary observations, several problems were identified. Detailed observations of the working crew formed the basis for cycle charts that outlined the sequence of steps and the duration of each step for a particular activity. Formwork installation, concrete pouring, and removal of formwork were the activities under observation for this report. A more detailed look at individual workers was produced in the form of balance charts. This allowed a thorough investigation of the type of work each worker was doing whether effective, contributory, or non-contributory. Based on the observations from several site visits, recommendations were put forth to improve operations of the project and therefore productivity. Performing productivity analysis is an effective tool that is used to ensure employees are meeting expectations. By streamlining activities and employing an efficient crew, a business can realize substantial gains in term of faster construction, fewer resources, and reduced labour. These factors are contribute to reducing costs and improving the competitiveness of the business. Efficiency however cannot come at the sacrifice of quality.
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5.0 Acknowledgements Thank you to Paul MacKichan at Intracorp Developments Ltd. for informing us about the site specifics, allowing us to venture onto the site (with the proper attire), and for looking out for our safety on site. Roger Woodhead, a sessional lecturer at The University of British Columbia and President of Woodhead Consultants, provided us with invaluable advice when we were just beginning this project and really helped us sort through our thoughts. A sincere thanks to Mr. Tom Nowak, the superintendent of the Chancellor House project with CitiWest Developments. Tom graciously sat down with us and explained the entire formwork process to us, answered any questions we had, and allowed us to observe his crew for this project.
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Appendix A. Site Observation Tables Day One AMAC Consultants
Project: Chancellor House Productivity StudyDate: Feb. 13, 2004 Observer: Adam
Observat ion Worker # 1 Worker # 2 Worker # 3
Time
BUILDING FORMWORK11:10 E
hammer11:15 E
saw11:20 E
hammer11:25 E
place11:30 E
11:35 Cguide
NEW LOCATION - SAME WORKER11:40 E
formwork11:45 C
moving mat'lNEW LOCATION - SAME WORKER
11:50 Cmoving
11:55 EformworkNEW LOCATION - SAME WORKER
12:00 Eformwork
12:05 Esaw set-up
12:10 Esaw set-up
12:15 E E
12:20 Emeasuring
12:25 C Emoving formwork
12:30 E Eformwork hammer
12:35 E Cdrill moving mat'l
12:40 E C Observat ion Worker # 5 Worker # 6 Worker # 7
formwork brace Time
12:45 C E BUILDING FORMWORKbrace hammer 12:47 E C C
12:50 C E clamp brace bracewalking 12:53 LUNCH C E
12:55 E LUNCH talk-instructsaw set-up 12:58 LUNCH E
1:00 E measurecutting 1:03 E
1:05 E hammerhammer 1:08 LUNCH
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Observat ion Worker # 1 Worker # 2 Worker # 3
Time
RETURN FROM LUNCH2:00 E NP
hammer watch2:05 C
move2:10 E
hammer2:15 NP E NP
talking hammer talking2:20 NP E E Observat ion Worker # 1 Crane Crane Worker # 4
hammer brace Time Operator
2:25 E C NP REMOVE FORMWORKdrill walk watch 2:27 E
2:30 E remove boltsformwork 2:32 C E E C
2:35 E guide lift wall op. crane guidehammer 2:37 C C C E
wait to unhoo wait unhook wallBUILDING FORMWORK 2:42 E E E E
2:45 E E remove boltlower chain op. crane hook uphammer hammer 2:47 NP C C NP
2:50 E E talking ait to unhoo wait talkinghammer hammer 2:52 NP C C NP
2:55 E E talking wait to hook wait talkinghammer hammer 2:57 E C C
3:00 E NP prying wait to lift waithammer 3:02 C C C
3:05 NP NP moving ait to unhoo wait3:07 NP C
3:10 E NP hold wallhammer 3:12 C E E C
3:15 E E spot lift op. crane spothammer hammer
3:20 NP
Observat ion Worker # 1 Worker # 2 Crane Crane Worker # 4 Worker # 5 Worker # 6 Worker # 7
Time Rigger @ truck Truck Operator Operator
POURING CONCRETE INTO FORMWORK3:25 C E C C C C C C
spot fill bucket olding bucke wait wait wait wait wait3:30 C C C C E C C C
wait wait olding bucke wait pour guide guide spot3:35 C C C C E C C
wait wait olding bucke wait pour guide spot3:40 C E C C C C E
spot fill bucket olding bucke wait watch watch vibrate3:45 C C C C C C E C
wait wait olding bucke wait hold ladderwait for pou vibrate spotPOURING CONCRETE INTO FORMWORK - NEW LOCATION
3:50 C C E E C C C Cwait wait ower bucke op. crane spot wait for pou wait wait
3:55 C E C C C Cspot fill bucket hold bucket wait wait wait
POURING CONCRETE INTO FORMWORK - NEW LOCATION4:00 C C C C C E NP NP
hold bucket wait spot vib hook-up walk walk
22
Day Two
AMAC Consultants
Project: Chancellor House Productivity StudyDate: Feb. 16, 2004 Observer: Mehrdad
Worker 1A Worker 1B Worker 1C Crane Crane Op
PLACING/BRACING FORMWORK
5 E E E E E
Guiding Guiding Guiding Carying Holding
10 C C C C C
Securing Securing Bracing waiting waiting
Worker 2A Worker 2B
RIGGING REBAR TO CRANE
5 C Crig rebar to
crane/waitingrig rebar to
crane/waiting
Worker 3A Worker 3B
FORMWORK CONSTRUCTION
5 E N
drilling talking
10 E N
Drill/Hammer waiting
15 E C
Hammer get material
20 E C
Hammer cutting
25 E C
Hammer get material
30 N E
waiting cutting
Worker 4A Worker 4B
CONCRETE FINISHING
5 E E
Patching C leaning corners
Worker 5A Worker 5B
REBARING WALLS (SPLICING)
5 E E
placing/splicing placing/splicing
Worker 6A Worker 6B Crane Crane Op
PLACING/BRACING FORMWORK
5 C C E E
Guiding/bracing Guiding/bracing Carying Holding
Worker 7A
CLEANING FORMWORK SURFACE
5 Ccleaning
Sampling Time ( i )
Comment: Normally it takes to guys to make formwork. Normally one is busy and the second os waiting for the first to do his part . It takes a long time. The process needs to be improved.
Improvement: C reate cross-checked rebars onteh floor then lift them up in place. Hard to work on a ladder.
Improvement: C lean forwork after stripping the forms off concrete, when the concret is not hard and easier to remove.
23
SLAB REBARING
Worker 8A Worker 8B
5 E ERebar
Placing/splicingRebar
Placing/splicing
10 E N
Rebar Placing standing
15 ERebar
Placing/splicing
BRACING FORMWORK
Worker 9A Worker 9B
5 E C
bracing instructing
10 N N
Standing Standing
PLACING/BRACING FORMWORK
Worker 10A Worker 10B Worker 10C Crane Crane Op
5 N N C C C
waiting waiting sawing Carying waiting
10 C C C E C
bracing bracing bracing Carying waiting
PLACING/BRACING FORMWORK
Worker 11A Worker 11B Worker 13C Crane Crane Op
5 C E E E C
guiding/bracing guiding/bracing guiding/bracing Carying waiting
PLACING/TYING FORMWORK TOGETHER
Worker 13A Worker 13B Worker 13C Crane Crane Op
5 E E E E E
Guide/fasten Guide/fasten Guide/fasten Carying guiding
PLACING/TYING FORMWORK TOGETHER
Worker 14A Worker 14B Worker 14C Worker 14D Crane Crane Op
5 E E E N E C
Guide/fasten Guide/fasten Guide/fasten standing Carying waiting
10 E E E
fastening fastening fastening
Comment: It seems that guiding and fastening the forwork is a task that would take around 5 minutes. However it is sometimes done slower.
Improvement: slab rebaring seems to be a long and menenous process. The slab rebar cage could possibly be prefabricated instead of the job site or outsourced. It ties up the labour.
Comment: Formwork did not fit, so part of it had to be sawn with a chain saw and had to be hammered in place. Workers had to wait for sawing to be finished
Improvement: Formwork are not designed having constructability in mind, therefore bracing is not done very effectively in some instances. Example provided below.
Comment: There is no way to brace the form from the front. Since it is a flat surce with no parts sticking out. By attaching timber that sticks out a bit, a surface for attaching the bracing is created.Formwor
k
Tibmer
24
FIXING/REPARING FORMWORK
Worker 15A
5 N
Standing around looking at it
PLACING/BRACING FORMWORK
Worker 16A Worker 16B Worker 16C Worker 16D Crane Crane Op
5 E E C N E E
guiding guiding guiding standing Carying guiding
10 E C E N E C
brace brace brace standing Carying waiting
PLACING/BRACING FORMWORK
Worker 17A Worker 17B Worker 17C Worker 17D Crane Crane Op
5 E C C N C C
hammering holding holding standing Carying guiding
PLACING/TYING FORMWORK TOGETHER
Worker 18A Worker 18B Worker 18C Crane Crane Op
5 E E E E C
guide/fasten guide/fasten guide/fasten Carying guiding
REBARING WALLS (SPLICING)
Worker 19A Worker 19B
5 E E
PLACING/TYING FORMWORK TOGETHER
Worker 20A Worker 20B Worker 20C Worker 20D Worker 20E Worker 20F Crane Crane Op
5 E E C C N N E E
guide/fasten guide/fasten guide/fasten guide/fasten standing standing carying guiding
Comment: The concrete truck had to wait 30 minutes before loading it's first bucket. The bucket was left hanging in the sky for 15 minutes before the first form was ready for puring.
Comment: Some workers are multi-taskers. They move from one task to another. Others stay on one task and wait for the work to come to them.
Comment: One worker was hammering/fitting the botomn of the formwork since it wouldn't fit in place 2 other guys were holding it. During all this time the crane was tied up holding the forwork in the air
Comment: Connecting the corner formwork to the rest apeared to be very challanging and time consuming both before placing and after placing. On one occasion, the non-working foreman (site engineer!) stopped the work on that sectiona and spent a few minutes going through his drawings and matching it up with the section. This situation seemed to be a designers mistake or lack of sufficient detail in the original drawing.
Comment: On this last piecec of formwork that would conclude the formwork placement for the wall, 6 people were helping. Not a very efficient process since too many people were involved.
25
Day Three
AMAC Consultants
Project: Chancellor House Productivity StudyDate: Feb. 16, 2004 Observer: Amir
Feb. 25, 2004
1st 5 min 2nd 5 min 3rd 5 min 4th 5 min 5th 5 minForm Installation
worker 1 Guide 1 cont guide form cont hold brace, nmoved moved offworker 2 Brace + nailecont guide form eff nail brace, al moved moved offworker 3 Hook Person eff release hook eff nail brace, al moved moved offworker 4 guide 2 eff guide from eff hold brace, nmoved moved offworker 5 Cleaner np wait np wait cont sweeping cont sweeping cont sweepingworker 6 Cleaner np wait cont start cleaningcont sweeping cont sweeping cont sweepingworker 7 bolt guy --- not there --- not there eff bolting eff bolting eff bolting
1st 5 min 2nd 5 min 3rd 5 min 4th 5 minForm Removal
worker 1 Hook Person eff hook to craneeff detach form moved moved offworker 2 Form detachenp wait eff dettach formeff guide crane moved moved offworker 3 bolt remover np wait eff detach from eff guide crane moved moved offworker 4 crane cont holding fromscont hold form eff lift form eff carry movedworker 5 cleaner --- eff sweep eff sweepworker 6 cleaner ---- np talking eff sweep
1st 5 min 2nd 5 min 3rd 5 min 4th 5 minConcrete Pour
worker 1 Truck Driver eff drive to positcont mix /rig, wait cont mix /rig, wait cont mix /rig, waitworker 2 Rigger at theeff guide driver cont rig, wait np wait cont rig, worker 3 Bucket Guide 1 eff guide eff guide cont contworker 4 Bucket Guide 2 eff guide eff guide cont contworker 5 Bucket Handle Hook cont pull handle cont pull handle cont pull handleworker 6 Crane eff move aroundeff move aroundeff move aroundworker 7 Vibrator np wait eff Vibrate eff Vibrate
26
Note some observations marked contributary although not active for 2.5 min. This is done, because they could not do anything else and their presence is required for the consequent job. If the process is imporved we might gain productivity
1st 5 min 2nd 5 min 3rd 5 minFinishing Form Placement
worker 1 Bolt person 1eff boltinh np talking cont getting toolsworker 2 Bracing cont moving arnd eff saw, brace,mnp moving arndworker 3 Bolt person 2cont bringing toolscont bringing toolsnp watch, talk
1st 5 min 2nd 5 minConcrete Drum
worker 1 Driver eff drive back eff drive backworker 2 Guide1 cont guide np guideworker 3 Guide2 cont guide cont guide
1st 5 min 2nd 5 min 3rd 5 minRebar
worker 1 helper cont tools np waitingworker 2 rebarer eff rebaring eff rebaringworker 3 rebarer eff rebaring eff rebaringworker 4 Safety cap meff making caps eff making caps eff making caps
1st 5 min 2nd 5 min 3rd 5 minRebar Depot
worker 1 truck np flat bed np idle np flat bedworker 2 crane eff moving rebareff moving rebareff moving rebarworker 3 worker at fla cont hook rebars np wait cont hook rebarsworker 4 worker at de np wait eff guide, unhoonp waitworker 5 heler at deponp wait cont guide help np wait
Driveer had to wait off the site and then drove all th way back and faith. When arrived on site and was ready to pour, either propr place was not ready or the worker wasn't ready. This shows lack of coordination, so he had to
i
27
The two workers at the depot might be able to do other things, while the worker at the flatbed is hooking and guiding the crane to move the bars. Instead of waiting for 2.5 min they can wait for 1.5 min if the crane and the crew work faster
1st 5 min 2nd 5 minClean up after formwork
worker 1 sweeping cont sweeping cont sweepingworker 2 help np talking,smokecont collect broken piecesworker 3 block breake np talking np watchingworker 4 concrete finiseff scraping eff scraping
1st 5 min 2nd 5 min 3rd 5 min 4th 5 min 5th 5 minBuilding Formwork
worker 1 formwork bu eff sawing cont sawing eff hemmering np talking cont guide
1st 5 min 2nd 5 min 3rd 5 min 4th 5 min 5th 5 minbuilding formwork
worker 1 formwork bu eff hammering eff sawing eff hemmering np talking cont guideworker 2 formwork builder np smokingworker 1 formwork bu eff drilling eff nail cont moving mate np move arnd np talkworker 2 formwork bu eff sawing np moving arnd cont getting tools cont helping eff nailingworker 1 formwork bu np talk cont helping np mocing arnd cont lifting eff carrying
28
Appendix B. Cycle Charts – Expected Results
0 10 20 30 40 50 60 70 80 90 100
Time (mins)
Finishing
Close-up Panel
Elevation
One Side Panel
Blocks
Layout
Figure B-1. Expected cycle chart for formwork installation.
0 10 20 30
Time (mins)
Pour Bucket #2
Position Bucket
Move To New
Vibrate
Reload Bucket
Pour Bucket
Position Bucket
Load Bucket
Truck Mix
Truck Positioning
Figure B-2. Expected cycle chart for concrete pour.
29
0 10 20 30 40
Time (mins)
Finishing
Panel Removal
Hardware Removal
Figure B-3. Expected cycle chart for formwork removal.
30
Appendix C. Crew Balance Charts
Common legend:
Figure C-1. Initial side panel installation balance chart.
Worker Moves Off Site
In-effective Work (idle)
Contributary Work
Effective Work
100
75
50
25
0 Crane
Form G
uide
Form G
uide
Hook Person
Bracer
Cleaner
Cleaner
Support
M ove
Guide
Hold bar
Guide
Hold bar
Help Help
Brace Brace
Brace Brace Align Align
Un- hook
Clean Clean
Tim
e Pe
rcen
tage
(%
)
31
Figure C-2. Formwork removal balance chart.
100
75
50
25
0 Crane
Form G
uide
Form G
uide
Hook Person
Bracer
Cleaner
Cleaner
Support
M ove
Guide
Hold bar
Guide
Hold bar
Help Help
Brace Brace
Brace Brace Align Align
Un- hook
Clean Clean
Tim
e Pe
rcen
tage
(%
)
32
Figure C-3. Concrete pour balance chart.
100
75
50
25
0 Crane
Form D
etacher
Bolt Remover
Hook Person
Cleaner
Support
M ove
Wait
Det tache
Wait
Remove bolt
Hook
Det tache
Working of f site
Tim
e Pe
rcen
tage
(%
)
Lif t
Clean
Guide GuideWatch
33
Appendix D. Project Decision Table
Project Location
Type of ProjectActivities in the month of
FebContractor Comments Contact Infos
VST (behind Gage)
Residential and admin offices
Wood Framing, demolition, siesmic upgrading
Scott Canada Friendly manager, willing to help, mostly wood work
N/A
VST (behind Gage)
managers are yet to be talked to IntraCorpGood management, lot's of heavy duty work, managers were in meeting
N/A
VST (behind Gage)
5 storey residential and admin offices
Mainly excavation, maybe some footings
Dominion
Firendly people, had problem getting labours which had slowed them down since the beginning of the process
Ken Hrynyk 604 631 1000
Main libaray extension of the library
Heavy excavation and footings Ledcor
early stages of construction. professionaly organized site, had a lot of restrictions in terms of safety issues, however, they were in early stages and once we talk to them we might be able to get special permissions. Manager was not there, but have the contact info to talk to them
Earl McIsac 604 681 7500
CISR extension
extension of the building
concrete and steel structure, at higher levels
Stuart Olson
friendly manager, willing to help, the project was in later stages, we can contact the manager for a site tour (for safety etc) if we want to start working with him.
Tony Boot 604 827 5487
34
Appendix E. Labour Utilization Calculations LUF calculation for Concrete Pour Balance Chart Effective work % Effective Work Minutes 1 worker 100 151 worker 40 61 worker 40 61 worker 40 61 worker 70 10.51 worker 30 4.5Sum Eff 48 Cont work % Cont Work Minutes 1 worker 45 1.68751 worker 20 0.75Sum Cont at 0.25 2.4375 1 worker 60 3.151 worker 60 3.151 worker 60 3.151 worker 30 1.575Sum NP at 0.35 11.025 Sum Worker utlization hour (min) 61.4625 7 15 Total amount of man hour (min) 105 LUF = Sum Woker Utili Hours / Amount of man hour 59%
35
LUF calculation for Formwork Removal Balance Chart With the third worker working Eliminating the third worker The first four workers work for only 10 min 3rd wroker eliminated thus time is reduced by 10min his effective work (30%) split between the two ther worker Their job increased by 30% * 15 min Effective work % Effective Work Minutes Effective work % Effective Work Minutes 1 worker 70 10.5 1 worker 70 10.5 1 worker 30 4.5 1 worker 45 6.75 1 worker 30 4.5 1 worker 45 6.75 1 worker 45 6.75 1 worker 45 6.75 Sum Eff 26.25 Sum Eff 30.75 Cont work % Cont Work Minutes Cont work % Cont Work Minutes 1 worker 10 0.375 1 worker 10 0.375 1 worker 30 1.125 1 worker 30 1.125 1 worker 10 0.375 1 worker 10 0.375 Sum Cont at 0.25 1.875 Sum Cont at 0.25 1.875 Sum Worker utlization hour (min) 28.125 Sum Worker utlization hour (min) 32.625 Total amount of man hour (min) 55 Total amount of man hour (min) 49.5 LUF = Sum Woker Utili Hours / Amount of man hour 0.511364 LUF = Sum Woker Utili Hours / Amount of man hour 0.659091
