Illustrate multiple activities chart with the help of a diagram. Also explain techniques of work measurement.

Multiple Activity Charts

Multiple Activity Charts (or Multi-Activity Charts) are a very useful tool for understanding the flow of work in a cyclical process and as a consequence understanding which resource is controlling the overall progress of the work. The tool can be used to model different scenarios to determine the optimum mix of resources for the work.

The example below is based on using a tower crane to lift concrete from the street to a high floor for placing. Each resource is represented by a column; time is on the vertical axis.

Time	Truck & Crew	Crane & Skip	Placing Crew	Finishing Crew
1 min	Fill skip	Skip filling	Wait	Wait
2 min
3 min	Wait	Hoist Skip
4 min		Skip emptying	Place and compact concrete
5 min				Smooth and finish concrete
6 min		Lower skip	Wait
7 min	Fill skip	Skip filling
8 min
9 min	Wait	Hoist Skip
10 min		Skip emptying	Place and compact concrete	Wait
11 min				Smooth and finish concrete
12 min		Lower skip	Wait
13 min	Fill skip	Skip filling

  

In this example, the crane (or more accurately the crane skip) is critical. On way to reduce the cycle would be to use two skips. One skip could be being filled while the other is emptied and all that would be needed is a few seconds to change over the crane hook when the newly emptied skip is lowered to the ground.

 

Time	Truck & Crew	Skip 1	Skip 2	Crane	Placing Crew	Finishing Crew
1 min	Fill skip 1	Skip filling
2 min
3 min	Fill skip 2	Hoist Skip	Skip filling	Hoist Skip 1
4 min		Skip emptying		Skip 1 emptying	Place S1 concrete
5 min						Smooth and finish concrete Smooth and finish concrete Smooth and finish…..
6 min		Lower skip		Lower skip 1
7 min	Fill skip 1	Skip filling		Change Hook
8 min			Hoist Skip	Hoist Skip 2
9 min			Skip emptying	Skip 2 emptying	Place S2  concrete
10 min
11 min			Lower skip	Lower skip 2
12 min	Fill skip 2		Skip filling	Change Hook
13 min		Hoist Skip		Hoist Skip 1
14 min		Skip emptying		Skip 1 emptying	Place S1 concrete
15 min

We have now reduced the cycle from 6 minutes to 5 minutes per load at the cost of hiring an additional concrete skip. The cycle could be further reduced if the hook change time is minimised. This may not sound much but if there were 30 skip loads of concrete in the pour and the cycle time could be reduced from 6 minutes to 4, the hour saved would reduce the cost of the pour by around $2,000 to $3,000. The next question though is how would the finishing crew manage? They are now working 100% of the time and arrangements may be needed for the placing crew to help them keep up with the increased pour rate.

Multiple Activity Charts a very simple technique that can provide valuable insights to help optimise any cyclical process that involves several different resources. They can also provide a valuable tool for monitoring progress in critical situations where a detailed understanding of the workflow is needed.

The difference between these types of analysis and bar-charts or CPM networks is the focus is on optimizing resource usage in a repetitive / cyclical process. Once the resource usage and cycle time are optimised, the resulting overall duration can be incorporated into the main project schedule or Line-of-Balance (LOB) chart.

Another key difference between Multiple Activity Charts and bar charts is the time unit. Multiple Activity Charts typically work in hours or minutes (and occasionally fractions of minutes). Bar-charts typically have a timescale of days and weeks.

Work Measurement Studies-

Work Measurement Study is a general term used to describe the systematic application of industrial engineering techniques to establish the work content and time it should take to complete a task or series of tasks.

Work measurement is a productivity improvement tool. Before improvements can be made, the current productivity level of an organization must be measured. This measurement is then used as a baseline to determine if improvement projects have resulted in genuine improvement.

Work measurement helps to uncover non-value added areas of waste, inconsistency, and non-standardization that exist in the workplace. Work measurement studies uncover ways to make work easier, and to produce products or services more quickly and economically.

Work is measured for four reasons:

à To discover and eliminate lost or ineffective time.

à To establish standard times for performance measurement.

à To measure performance against realistic expectations.

à To set operating goals and objectives.

Work measurement involves the use of engineered labour standards to measure and control the amount of time required to perform a specific task or tasks. While labour standards are most commonly associated with manufacturing or production environments, standards are used in many other types of settings including, but not limited to: service or administrative, warehousing and distribution, retail, janitorial, medical and utilities.

Work Measurement Techniques-

Under the work measurement umbrella there are a number of techniques for collecting the information necessary to develop engineered labour standards.

Time Study is the most widely used work measurement technique that employs a decimal minute stopwatch to record and determine the time required by a qualified and well-trained person working at a normal pace to do a specific task under specified conditions. The result of the time study is the time that a person suited to the job and fully trained in the specified method will need to perform the job if they work at a normal or standard pace.

Predetermined Time Systems are a technique of motion study and time standards development. The motions of the work or task performed are recorded. Each basic motion has a time value associated with it. Once all the motions for the task have been recorded, the time values are totalled and the standard time for the operation is developed.

Standard Time Data (Standard Data) is a generic term given to a collection of time values. Standard data uses work elements from time studies or other work measurement sources making it unnecessary to restudy work elements that have been timed adequately in the past. These element times are extracted from studies and applied to jobs or tasks with the same element(s). Some examples of standard data development include graphs, tables, charts, formulas and spreadsheet programs.

Work Sampling is a random sampling technique (statistical sampling theory) that involves observing the worker(s) at randomly selected times and recording the type of activity that is observed at that instance. Work sampling is most commonly used to collect information for allowance calculation, to determine the distribution of work activities, and to determine the productive and non-productive utilization of workers.