W15_Reginald Nwachukwu_OUT OF CONTROL Analysis (SPC) on Determined Activity Durations

1. Problem Definition or Opportunity Statement:

To use SPC process capability and control charts to evaluate OUT OF CONTROL analysis of  activity duration data points and the process used to calculate them. 

Following Dr. Paul D. Giammalvo instructions on my W14 blog post at http://bistro12.blogspot.com/2013/03/w14reginald-nwachukwudetermining.html#comment-form 
it is required to evaluate the determined activity durations and the process used to calculate them using the Statistical Process Control. SPC measures both process CAPABILITY and CONTROL using CONTROL CHARTS and PROCESS CAPABILITY tools an techniques.

2. Development of Feasible Alternatives:

The variability associated with determining actual activity durations for large construction projects make it a daunting task and requires a concerted efforts from the project scheduler. To apply SPC to the data points available (unconstrained activity duration), the following options may be developed for this analysis.

(i) Historical Duration Data

(ii) Unconstrained Activity Duration

3. Development of Outcome for Each Alternative:

The development of outcome for each alternative will require the scheduler critical skills and understanding and use of  SPC control charts and process capability indices to analyse data (both attribute and value or variable data). To this end the outcome for alternatives will strictly be based on the outcomes of the statistical processes applied to the data points. Hence, the TYPE of CONTROL CHART selected is based on the data type (Attribute or Variables) and sample number (n).

(i) Develop control charts using X and R Chart, X and s Chart
(ii) Calculate Process Capability Indices Cp Cr, Cpl Cpu, Cpk
(iii) Analyse and describe the results obtained.

4. Selection of the Acceptable Criteria:

To examine is there any internal causes for an out of control situation, Brassard and Ritter state a process is said to be “out of control” if either one of these below is true:

1.        One or more points fall outside the control limits (outside + 3 Sigma and – 3 Sigma)

2.       Two points, out of three consecutive points, are on the same side of the average between + 2 Sigma and + 3 Sigma, between – 2 Sigma and – 3 Sigma, or beyond

3.       Four points, out of five consecutive points, are on the same side of the average between + 1 Sigma and + 2 Sigma, between – 1 Sigma and – 2 Sigma, or beyond

4.       Nine consecutive points are on the same side of average

5.        There are six consecutive points, increasing or decreasing

6.       There are 14 consecutive points that alternate up and down

7.        There are 15 consecutive points between mean and + 1 Sigma and mean and – 1 Sigma

To examine is there any process causes for an out of control situation, Brassard and Ritter state a process capability is to determine whether a process, given its natural variation, is capable of meeting established customer requirements or specifications.

Process Capability Ratio (Cp)

5. Analysis and Comparison of Each Alternative:

From results obtained from the development of outcome from each alternatives; the control charts showed data point that were OUT OF CONTROL. This could be due to workload factor and workhours assumed for calculation of Ordinary Duration (OD) data point. This will be revise to reflect the expected duration based on work hours

6. Selection of Preferred Alternative:

The Control charts - X-Dbl bar and R-Bar and X-Dbl Bar and s-Bar charts were used to identify data points (Activity Durations)  that are OUT OF CONTROL, whereas the Process Capability was used to establish that the process used to obtain data points is not flawed and that the process is capable at a value of 1. 

7. Performance Monitoring and Evaluation of Results:

The control charts and the process capability method are valuable tools that can be employed by project teams and project controls to monitor the boundary of their data points collected and recorded while carrying out their daily activities or implementing projects. 

References:

 1. AACE International (2012) Skills and Knowledge of Cost Engineering (5th Edition Revised) pp. 28.3-28.7  AACE International Morgantown W.V. 

2. Brassard, M. & Ritter, D.(2010). The Memory Jogger 2: Tools for Continuous Improvement and Effective Planning, pp.53-70,173-177,182-187

3. AACE International (2008) Planning and Scheduling Professional certification Guide (First Edition Revised) pp. 143-145  AACE International Morgantown W.V. 

4. AACE International Recommended Practice No. 49R-06 (2012) Determining Activity Duration  pp. 1 - 12 AACE International Morgantown W.V

W14_Reginald Nwachukwu_Determining Activity Durations

1. Problem Definition or Opportunity Statement: 

To estimate the Activity Duration for the construction of 27.0m Length Precast Box Culvert.

It required to estimate and determine the duration required to complete the construction of 27.0m length precast box culvert. The lead scheduler for the project have provided some historical data, and have asked me to evaluate them and make probable duration estimates to for construction of precast box culvert.

Figure 1- 1 Installation of Precast Box Unit on a Highway Project (Source, Author)

Table 1-1 Historial Duration Data from Past Project

2. Development of Feasible Alternatives:

Development of feasible alternatives for determining activity duration will be based on the techniques or  methods illustrated AACE International Recommended Practice No. 32R-04. These techniques have been evaluated and recommended as practice guides for calculating durations. These techniques constitutes the alternatives and includes:

(a) Unconstrained Activity Duration:

(i)  PERT Calculations
(ii) Descriptive Statistics
(iii) Normal Distribution Curve
(iv) Original Distribution (OD)
(iii) CPM Method (PDM Method)
(iv) Cost Estimates

(b) Constrained Activity Duration

(c) Revised Activity Duration to Meet Project Requirements

For the purpose of brevity and clarity, only Unconstrained Activity Duration technique have been used for analysis and evaluation of feasible alternatives.

3. Development of Outcome for Each Alternative:

The various techniques/methods under Unconstrianed Activity Duration were evaluated using Project Historical Data provided and their durations impacts as shown below viz:

(i) Descriptive Statistics:  
Basic descriptive statistical calculations were performed to determine durations as shown on Figure 1-2

Figure 1-2 Determination of Activity Duration Using Statistical Description

Figure 1-3 Frequency Polygon to Determine of Activity Duration Using Statistical Description

(i) Normal Distribution Curve: 

This technique uses the Normal Distribution functions in Microsoft Excel 2007 (NORMDIST, AVERAGE, STDEV, NORMINV, etc.) to compute activity duration using the Normal Bell-shaped curve.

Figure 1-4 50% Percentile showing 20 Workdays 

Figure 1-4 95% Percentile showing 23 Workdays 

(iii) Original Duration Calculations:

4. Selection of Acceptable Criteria:

Selection of acceptable criteria that may be applied to determining activity durations will be a criteria that is realistic and reflect the size, scope and contract requirements defined for that activity. Methods used to develop the outcomes are both Stochastic and Deterministic in nature. To this end, any technique that considered pertinent activity variables at the minimum possible duration will be selected.

5. Analysis and Comparison of Each Alternative:

(i) PERT Calculation :

Mean  = (17 + (4*20) + 23) / 6 = 20 Days
Range = 23 - 17 = 6 Days
Variance = Range/6 or Range/4 .........................[2]
Variance = 6/6 0r 6/4 = 1.5
Standard Deviation = (1.5)^2 = 2.25 Days

Duration (90% Confidence) = Mean + 1.3*S.D
                                             =  20 + 1.3*1.5  = 22 Days

(ii) OD Original Duration :    Duration  = 39 Days

(iii) Normal distribution Curve :    Duration  = 23 Days

(iv) CPM Method (PDM) :    Duration  = 23 Days

(v) Cost estimates :    Duration  = N/A

6. Selection of Preferred Alternative:
 Based on the activity duration determine, the preferred method will be the Original Duration that considered both crew size and workload factors which can greatly impact the duration of any activity.

7. Performance Monitoring and Evaluation of Results:

Performance and monitoring can effectively be implementated using the various tools developed for determining activity durations. This is achieved by collecting, recording and monitoring the actual duration expended to complete the activity been considered or under study.

References:

1. Humphreys G.C. (2002) Project Management Using Earned Value (2nd Edition) pp. 143 - 144 Orange CA Humphreys & Associates

2. AACE International (2012) Skills and Knowledge of Cost Engineering (5th Edition Revised) pp. 28.3-28.7  AACE International Morgantown W.V. 

3. AACE International (2008) Planning and Scheduling Professional certification Guide (First Edition Revised) pp. 143-145  AACE International Morgantown W.V. 

4. AACE International Recommended Practice No. 49R-06 (2012) Determining Activity Duration  pp. 1 - 12 AACE International Morgantown W.V.

W13_Reginald Nwachukwu_Analysis of Critical Path for the Construction of 27.0m Length Precast Box Culvert

1. Problem Definition or Opportunity Statement:

To identify and analyse the CRITICAL PATH (S) for the construction of 27.0m length precast box culvert

In continuation of the scheduling task by the schedule team discussed in the weekly blog post  http://bistro12.blogspot.com/2013/03/w12reginald-nwachukwuscheduling-270m.html the lead scheduler have further asked me to identify and analyse the CRITICAL PATH(S) necessary to accomplish the construction of the precast box culvert. He further instructed that management have approved only 18 WD workdays so as to move the construction team to another site. Table 1-1 below shows the Activity List and the relationships/logic and durations.

Table 1-1  Activity List with Relationships and Durations

2. Development of Feasible  Alternatives:

To develop feasible alternatives necessary to identify and analyse the critical path in the PDM network model developed for the construction of the precast box; four generally acceptable methods for critical path analysis were adopted as alternatives to optimise the PDM Schedule. These alternatives or methods includes:

(a.)  Lowest Total Float
(b.) Negative Total Float
(c.) Longest Path
(d.) Longest Path Value Method

For brevity, only the Least Total Float method have been applied to the schedule model using the following:

(i) Date & Float Constraints
(ii) Calender Date

3. Development of  Outcome for Each Alternative:

The schedule model is subject to analysis by constructing the ADM model and the original path duration for the schedule. Later, the various constraints were applied to the schedule model to evalute their impacts on the completion dates and the critical path(s).

Figure 1 - 1 ADM network model for the construction of precast box culvert.

Figure 1 - 2 PDM Original Path Duration with No constraints applied to the network model 

Figure 1 - 3 PDM network model with 4 Date Constraints applied to the network model

Figure 1 - 3 PDM network model with 3 Date Constraints applied to the network model

Figure 1 - 3 PDM network model with IMPOSED DATE applied to the network model

4. Selection of Acceptable Criteria:

Criteria used to selection the path(s) that are critical to completing the construction precast box will be based on the Least Total Float method where activities with least total float are selected as been on the critical path. Though this method does not give complete solution to identifying and analyzing CP, but it does provide insight into CP identification and analysis. Here, activities with the LEAST TOTAL FLOAT are construed to be on the CRITICAL PATH.

5. Analysis and Comparison of Each Alternative:

Analyzing and comparing the possible outcomes from step 3, the CRITICAL PATH remain the same irrespective of the different types of constraints applied to the network model and the IMPOSED DATE constraint only introduced NEGATIVE FLOAT for the Clear Site activity (-2 Days); but the CP remain same.

6. Selection of Preferred Alternative:

The preferred alternative is maintain the identified CRITICAL PATH ( B - E - F - G - J - K - M ) which remain unchanged after applying date constraints due to material delivery or minimum no of days necessary for concrete to gain strenght before loading it ( for base slab take 3DAYS).

7. Performance Monitoring and Evaluation of Results:

The performance of the network model will be monitored by establishing the changes or other constraints that might impact the completion date and results obtained from the performance can be further evaluated to reflect the TRUE representation of the activities necessary to complete the precast culvert.

References:

1. Humphreys G.C. (2002) Project Management Using Earned Value (2nd Edition) pp. 143 - 144 Orange CA Humphreys & Associates

2. AACE International (2012) Skills and Knowledge of Cost Engineering (5th Edition Revised) pp. 13.3-13.7  AACE International Morgantown W.V. 

3. AACE International (2008) Planning and Scheduling Professional certification Guide (First Edition Revised) pp. 143-145  AACE International Morgantown W.V. 

4. AACE International Recommended Practice No. 49R-06 (2010) Identifying The Critical Path pp. 4 - 8 AACE International Morgantown W.V.

W21_LUCKY_DETERMINING ROOT CAUSE(S) OF INCESSANT COMPRESSOR PACKAGE FAILURE

W21_LUCKY_DETERMINING ROOT CAUSE(S) OF INCESSANT COMPRESSOR PACKAGE FAILURE

1.      Problem Recognition, Definition, Root Cause Analysis and Evaluation

 

(i)                 Problem Recognition

In recent times, there has been an incessant failure of the compressor packages at one of our plants. This submission is being prepared to address the human factor aspect of this failure at this time.

(ii)               Problem Definition

Why is there a lack of predictive maintenance culture at this plant?  Will change management going to work at this plant?

Using CAWTOE[i] methodology for a better understanding of the issue exploring the various perspectives, we have

C – Customer’s Perspective: The customer is not pleased with the performance as it affects their crude oil production, our company’s reputation and continued revenue

A – People (Actors): The employees are unaware of this big picture as most of them feel they work too hard

T- Transformation Process: All employees in the plant have undergone ACCPAC Service manager training (the maintenance software used in the operations department) and a majority of them are proficient in its use.

W- World View: The service performance of similar company plants elsewhere in the world is 98.93% [Company Data]

O - Process Owner: Operations department managers are equally not impressed with the results.

E – Environmental Constraints: The Maintenance Repair and Overhaul (MRO) parts are imported from the OEM overseas either by air or sea freight which takes between 6 – 8 weeks in the minimum and sometimes longer to reach Nigeria. Custom clearing takes between 1 -4 weeks depending on the category of goods.

                        a.         Assumptions

There are existing planned maintenance program inclusive of schedules and resources to begin with.

(iii)             Root Cause Analysis and Evaluation

The purpose is to figure out why this problem occurred and keeps recurring. I am using the popular Root Cause Analysis to do this. The methodology is based on the premise that systems and events are interrelated such that an action in one area triggers an action in another area and so on. Thus it is possible to trace back those actions to the starting point as reasonably acceptable.

I will follow the five step process[ii]  of define the problem, collect data, identify possible causal factors, identify the root cause(s), and recommend and implement solutions

2.      Development of feasible alternatives (Causal factors)

There are three basic types of causes comprising of Physical causes (tangible material failure), Human causes (People did or did not do something) and Organizational causes (Faulty System/process or policy).

3.      Development of outcomes  for each alternative (causal factor)

The outcomes for each causal factor alternative are as follows:

Using the 5 Whys ^[iii] approach:

Sequence of events leading to the problem:-

Top level causal factor (Header) can be classified thus:

(1)   Increased volume of breakdown work (Physical Cause, Human causes and Organizational causes)

(2)   Lack of adequate knowledge and skill (Physical Cause, Human causes and Organizational causes)

(3)   Lack of commitment to implement maintenance plans (Physical Cause, Human causes and Organizational causes)

(4)   Lack of appreciation of the value of preventive maintenance (Physical Cause, Human causes and Organizational causes)

(5)   Poor Attitude towards maintenance (Physical Cause, Human causes and Organizational causes)

 

4.      Selection Criteria causal factors

The selection criteria are as follows:

1.      Short time to implement solution for

2.      Implementation impact level

3.      Minimal Cost (within budget)

 

5.      Analysis and Comparison of the alternatives (causal factors)

 

Attempting to use the non-compensatory model of satisficing[iv] to narrow down a causal factor,

Selection Criteria (Attribute)	Minimum Acceptable Value	Maximum Acceptable Value	Causal Factors Requiring further investigation for now
Short Time to implement solution	-	10 days	#4, #5
Solution implementation impact level	High	-	#5
Minimal cost of solution implementation	-	Use currently available resources	#5

Table 1: Feasible Ranges for Satisficing (By Author)

 

6.      Selection of preferred alternative (causal factor)

Comparing the attributes values against the feasible range reveals that addressing the poor attitude towards maintenance will provide the quickest solution at solving the problem of incessant compressor package failures. Incidentally, this aligns with what the Root Cause Analysis reveals as this causal factor lies at the root of the problem.

7.      Performance monitoring and post evaluation of results

I would need to address the poor attitude towards maintenance by proposing training for all plant operations personnel in basic maintenance management skills including basic project management skills, and monitor and evaluate the results six months down line.

Reference

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[i] Mindtools, (2013). Root Cause Analysis Tracing a problem to its origin. Retrieved from http://www.mindtools.com/pages/article/newTMC_80.htm

 

[ii] Nasa, (2013). Root Cause Analysis. Retrieved from http://www.au.af.mil/au/awc/awcgate/nasa/root_cause_analysis.pdf

 

[iii] ISixSigma, (2013). Determine The Root Cause: 5 Whys. Retrieved from http://www.isixsigma.com/tools-templates/cause-effect/determine-root-cause-5-whys/

 

 

[iv] Sullivan, W., Wicks, E., Koelling, P., Kumar, p., & Kumar, N. (2012).Chapter 14 Decision making considering Multiattributes (p. 577). Engineering economy (15^th edition). England: Pearson Education Limited.