022 b construction croductivity-write system
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On-Site Construction Productivity Using the WRITE System
Existing construction productivity measurement techniques are not capable of providing the real-time productivity data to project managers and engineers for analyses and sharing the data among participants involved in construction operations.
On-Site Construction Productivity Using the WRITE System On-site productivity problems cannot be taken
just in time. To address these shortfalls, the Wireless Real-
time Productivity Measurement (WRITE) System was developed.
it can measure the on-site construction productivity in real time.
In addition, an on-site construction productivity improvement model using the WRITE System and the benchmark data was developed.
WRITE SystemObjective Approach- The real-time productivity data measured by
the WRITE System was compared to the benchmark productivity data.
The results of the comparison provided the necessary information for:
project management team to determine if immediate actions should be taken
WRITE System Secondly, it provides an advanced
technology for managers to determine on-site construction productivity in real time.
Improving on-site could be taken just in time if needed.
These advancements enhance the contractors’ capability of managing construction projects.
WRITE System Productivity data have been widely used as
performance indicators: to evaluate construction operations throughout
the entire phase of construction. Construction companies must continuously
track productivity in order to measure their performance.
1. Maintain profitability2. Prepare future biddings
WRITE System
Measuring productivity on site has been an important task in the construction industry.
In the past many On-site productivity measurement techniques have been developed. They include:
questionnaires stopwatch studies photography time-lapse videos video-taping
WRITE System In recent years, real-time
monitoring systems have become key methods to reduce the gap between:
1. Actual
2. planned production rates
In an effective way.
On-Site Construction Productivity Using the WRITE System A real-time video system was
developed by Everett and Slocum.
For monitor lifting activities of crane in attempts to improve both productivity and safety of crane operations.
WRITE System
Since 2000, wireless technologies, such as: global positioning system (GPS) radio frequency identification (RFID)
system, were utilized Have been adopted in construction In
order to track the current status of the resources and activities.
On-Site Construction Productivity Using the WRITE System
A GPS technology was used to automatically measure earthmoving performance.
It is by identifying the locations of equipment at regular time intervals,
Converting the information into project productivity (Navon and Shpatnitsky 2005).
WRITE System
A web-based camera was used to monitor interior construction operations.
This web-based network technology produced an opportunity to avoid using a wired network connection.
In a congested construction jobsite not a good idea (Kang and Choi 2005).
On-Site Construction Productivity Using the WRITE System Existing on-site construction productivity
measurement methods have some common limitations.
They are unable to provide the real-time productivity data for analyses, and sharing the data among participants.
WRITE SystemDEVELOPMENT OF WRITE SYTEM The developed WRITE system
includes: A video camera; a digital camera; a data processor;
WRITE System an AC transformer; two antennas; A laptop computer as shown in Fig 1. The preliminary test results indicated that
the developed system can measure the on-site construction productivity accurately (Kim 2008)
WRITE System
Framework of the WRITE System
Development of the Productivity Improvement Model
After building the WRITE System; a model for the on-site construction
productivity improvement was developed. In this model: the first task is to collect pictorial data in
the construction site using the WRITE System.
Development of the Productivity Improvement ModelThe second task is: to determine the real-time productivity data
which is the ratio of working and nonworking time.
The third task is: to compare the real-time productivity data
with the productivity benchmark data.
WRITE SystemDuring the comparison, Management team MUST answer two
questions, and then make productivity improvement decisions accordingly.
The first question whether the real-time productivity data is
higher than the benchmark data at which action should be taken.
WRITE System
If the answer for this question is no, management needs to take action
immediately to improve the on-site productivity.
If it is yes, management goes to the next stage to
compare the real-time data with the acceptable benchmark data.
WRITE System
If the real-time data is > than the acceptable benchmark data,
No action is needed. Otherwise, management needs to be aware that
action may be needed in the near future. It follows with a close monitoring at the construction
site. The developed model can be utilized for the entire
period of construction or for the segments of construction.
WRITE System
Work Breakdown Structure (WBS) The work breakdown structure (WBS) has
been widely used to manage the project. WBS is defined as “a deliverable-oriented
grouping of project elements”. which organizes and defines the hierarchical
structure of the entire project (Jung and Woo 2004).
WRITE System It is often used in the complex construction
projects. To identify project information. Improve the efficiency of control
processes.
WRITE System A WBS shows the relationship of all
project activities. It is at important and decisive levels. WBS makes each activity more
manageable and measurable. The number of levels depends on the
size and complexity of the projects (U.S. Department of Energy 1997).
On-Site Construction Productivity Using the WRITE System The bridge reconstruction project used in
the field experiments was broken down into four levels. They are:
including Level 1 (project) Level 2 (work zone) Level 3 (activity) and Level 4 (operation) Examples of the levels of steel girder
bridge WBSs are shown in Table 1.
Table 1. WBS for steel girder bridge reconstruction Level 1 (Project) Level 2 (Work Zone) Level 3 (Activity) Level 4 (Operation)
Steel Girder Bridge General Mobilization Set up Crane Abutment Traffic Control Moving concrete safety barrier Pier 1 Demolition Driving pile Pier 2 Excavation Forming Pier 3 Abutment 1 Structural excavation North side Abutment 2 Slope protection (filter fabric and
rock) South side Pier Drill Shafts Set bearing devices Span 1 Pier Columns Unload beams Span 2 Pier Cap Set beams Span 3 Slope protection Install diaphragms Span 4 Beam Setting Bolting and tightening splice Deck Forming Ground splice Reinforcing Deck Prepare deck material Bridge Barrier Rail Prepare deck forming Concrete Barrier Overhangs Backfill Abutments Strip Approach road Place backwall (strip drain & backfill)
Tying rebar Pouring and curing Others Strip and check elevation
WRITE System
Determining Productivity Benchmark Data Benchmarking has been used as a tool to
improve productivity since the early 1980s. The Construction Industry Institute (CII) has
established construction productivity metrics and a reporting format for construction productivity benchmarking and improvement (Han et al. 2005).
WRITE SystemActual working time of construction
workers is at 56% in nuclear plant construction projects (Hewage and Ruwanpura 2006).
Christian and Hachey (1995) studied concrete-placement operations. Their finding showed that:
WRITE SystemThere are 61% working time and
39% nonworking time. According to the previous
research projects, the ratio of working time and nonworking time ranges approximately from 50:50 to 60:40.
WRITE System There is no consensus on the
acceptance ratio of working time verse nonworking time in the construction industry.
because construction projects have different natures such as different types of projects, activities, and operations.
WRITE System
Productive and non-productive time for five bridge operations were identified as:
deck forming tying rebar installing finisher
WRITE System backfilling and placing approach road footing. A total of 66 hours of video tapes were
recorded using the WRITE System to determine the productivity rates for the five bridge operations.
On-Site Construction Productivity Using the WRITE System These videos were all taken zoomed-in to
clearly identify: the productive time; nonworking; time for each operation. The ratio of productive and non-productive
time was: 86% and 14% on average as shown in Table 2.
WRITE System Table 2. Ratio of working and nonworking time determined by
the WRITE System Operation Time (Second) Percentage (%) Time Nonworking(nonproductive) Time Working Time Nonworking Time Deck forming 24,720 2,160 92 8 Tying rebar 40,320 5,880 87 13 Installing finisher 71,230 21,100 77 23 Placing backwall, strip drain, and backfill44,850 1,950 96 4
Grade and tie approach road footing 21,275 2,725 89 11
Total 202,395 33,815 86 14
WRITE System The benchmark data were based on
professional intuitions about rates of working time and nonworking time for each of the five bridge construction operations.
WRITE System Table 3. List of survey construction
professionals Name Company Construction Specialty
Position Ken Johnson BRB contractors, Inc. Bridge
Project Manager Mike Laird BRB contractors, Inc. Bridge and
Plant Project Manager Ray Rinne A.M. Cohron & Son, Inc. Bridge Superintendent Christopher J. Rech A.M. Cohron & Son, Inc.
Bridge Project Manager
WRITE System Table 4 shows acceptable ratios provided
by four survey participants. The overall average ratio for working time
(WT) was 81% and overall average ratio for nonworking
time (NWT) was 19%. Tying rebar had the highest nonworking
ratio of 21%, while deck forming had the lowest rate of
16%. T
On-Site Construction Productivity Using the WRITE System
According to the survey participants, they can accept the working time ratio of at least 79% for these bridge operations.
Table 5 presents ratios at which action should be taken by project managers to improve on-site construction productivity.
WRITE System The overall average ratio for WT was
75% and overall average for NWT was
25%. Tying rebar had the highest
nonworking time rate of 28%, while deck forming had the least
nonworking time rate of 23%.
Table 4. Acceptable ratio Operation BRB 1 BRB 2 A.M. Cohron 1 A.M. Cohron 2 Average WT (%) NWT (%) WT (%) NWT (%) WT (%) NWT (%) WT (%) NWT (%) WT (%) NWT (%) Deck forming 85 15 80 20 85 15 85 15
84 16 Tying rebar 80 20 75 25 80 20 80 20
79 21 Installing finisher 85 15 75 25 85 15 85 15
82 18 Placing backwall, strip drain, and backfill 70 30 80 20 85 15
85 15 80 20 Grade and tie approach road footing 80 20 80 20 85 15
85 15 82 18 Average 80 20 78 22 84 16 84 16 81
19
Note: WT–Working Time; NWT–Nonworking Time
WRITE System Table 5. Ratio at which action should be taken Operation BRB 1 BRB 2 A.M. Cohron 1 A.M. Cohron 2 Average WT (%) NWT (%) WT (%) NWT (%) WT (%) NWT (%) WT (%) NWT (%) WT (%) NWT (%) Deck Forming 75 25 75 25 80 20 80
20 77 23 Tying rebar 70 30 70 30 75 25 75 25
72 28 Installing finisher 75 25 70 30 80 20 80
20 76 24 Placing backwall, strip drain, and backfill 60 40 75 25 80
20 80 20 74 26 Grade and tie approach road footing 70 30 75 25 80 20
80 20 76 24 Average 70 30 73 27 79 21 79 21
75 25
Note: WT–Working Time; NWT–Nonworking Time
WRITE System Table 6 presents the results of the comparison
between the benchmarking data from the survey and the real-time productivity data determined by the WRITE System.
For the operation of installing finisher, the nonworking ratio of 24% was equal to the
ratio at which action should be initiated by the construction manager.
The rest of operations had larger working time ratios than the minimum required working ratios.
Table 6. Data comparison between the WRITE System and the benchmarks Operation Acceptable Ratio Ratio at which action should be taken WRITE System WT (%) NWT (%) WT (%) NWT (%) WT
(%) NWT (%) Deck Forming 84 16 77 23 92 8 Tying rebar 79 21 72 28 87 13 Installing finisher 82 18 76 24 76 24 Placing backwall, strip drain, and backfill 80 20 74 26
96 4 Grade and tie approach road footing 82 18 76 24
89 11 Average 81 19 75 25 88 12
Note: WT – Working Time; NWT – Nonworking Time
WRITE System By comparing the rates from the WRITE System
to the benchmark data, project managers can take actions for improving on-site construction productivity in real time.
As shown in Table 7, there are three cases that project managers can make decision using the developed model.
First, if the productivity ratio measured by the WRITE System is higher than the acceptable ratio,
then, no action is required.
WRITE System Second, if the ratio is between acceptable
ratios and ratios, at which action should be initiated, then, management needs to be aware that
an action may be needed in the near future.
Finally, if the ratios are lower than the minimum required rate,
then, the project manager needs to take actions immediately.
WRITE System Table 7. Making management decisions using
the WRITE System No. Ratios from the WRITE System Action
1 Higher than acceptable ratios No action needed
2 Between acceptable ratios and ratios at which action should be taken Aware that action may be needed
3 Lower than ratios at which action should be taken Action is required