LET'S KILL GANTT

A few months ago Profesor Gui Ponce de León from University of Michigan came to Perú and gave us a speech called “Gantt Chart rest in peace”, of course I was there.

In that speech he introduced us a new tool called GPM to represent and review the schedule of a Project, pointing out its advantages over Gantt. I´m not going to describe here what’s GPM because I haven’t used it yet, but those who are willing to know more about could try on this link http://pmatechnologies.com/ , here you could get more information regarding GPM from creator’s mouth.

In fact, just as Gui, I belong to the “Let´s kill Gantt Club”. Neverthless I confess that I have tried several times to kill Gantt and it is not only that I haven´t got  it, but Gantt emerged more powerful after each attack. That’s why I think Gantt continues as the best way to represent time of a Project.

For instance this was my last try:

Issue

In Construction, generally, manpower is grouped in crews which go from one work station to another and so on through Project’s life. Knowing how the crews move would be very useful for planning a Construction Project but it is no possible in Gantt chart, let’s check why.

Henry Gantt invented his famous chart in 1915, for automobile industry and during Ford age, it means assembly line was already operating. One of the biggest differences between automobile industry and construction industry is that while in the first one manpower is static, materials goes towards them by using conveyor belts,  in the second one manpower is moving all the time in search of  work to complete.

So, how can we check crew rotation?. I didn’t have to go any further, the answer is in the same Gantt chart.

Analysis

Gantt chart has two dimensions: the first one is the timeline located in horizontal axis and the second one is the work breakdown structure located in vertical axis (See Chart 01)

Chart 01: Gantt’s structure

We would need a third dimension to show crew rotation up; and there is only one moment in which Gantt chart acquires a third dimension, it is when we identify critical activities and non critical activities by using colors. Therefore it is possible to get this third dimension calling for colors.

In order to get an easy way to visualize this crew rotation, it would be very useful to make a structure which shows a timeline in the horizontal axis and a list of work stations where crews are moving through in the vertical axis (See Chart 02).

Chart 02: Crew movement structure

We can notice timeline matches with Gantt’s, but list of work stations doesn’t with work breakdown structure necessarily. So the only one condition, not so hard to achieve, is that items on list of work stations and activities of Gantt work breakdown structure must be the same.

Finally, the most recommended for an easy visualizing is to set work stations on the last detail level as above and in the previous level we should place disciplines or types of crews, therefore it would be as follows:

Level 1: Project name

Level 2: Disciplines

Level 3: Work stations

Instructions

1-      Creating Project name.- In our example we will try a Hydropower plant (See Chart 03).

Chart 03: Detail level 1, Project name

2-    Creating Disciplines.- Work crews in a Powerhouse construction can be divided into four disciplines: Tests, Excavations, Civil Works and Mechanical – Electrical (See Chart 04).

Chart 04: Detail level 2, Crew disciplines

3-    Creating Work Stations.- In our example we create the tasks, but keeping in mind they must be work stations too (See Chart 05).

Chart 05: Detail level 3, Work stations

4-    Calculating durations and linking activities.- Generally crews into a discipline have the same amount of people, in others words they have the same performance too, therefore each duration is established by dividing quantity of work in each task over a performance rate of the corresponding discipline’s crew. In addition, we must link activities too, according to planned construction process. See Chart 06.

Chart 06: Durations and links assigning

5-    Identifying some possible paths for crews. For example between tasks ID16: CONCRETE ON POWERHOUSE (1^ST STAGE) and ID17: CONCRETE ON POWERHOUSE (2^ND STAGE) there is a 39 days gap, which can be filled by a non-linked task like ID27: CABLES TUNNEL with 40 days for duration. So we take advantage of these "non-linked" activities in order to get a continue work for the crew going through. We assign a color to identify each specific crew running through its activities or work stations. We have chosen green for this crew (See Chart 07).

 

Chart 07: Crew rotation planning

6-    In the same way, we can move some tasks or connect each other ones just being careful on keeping deadline date. In our example we can visualize crews rotation, for instance green crew of CIVIL WORKS discipline runs through the following path: ID16: CONCRETE ON POWERHOUSE (1^ST STAGE) -> ID27: CABLES TUNNEL -> ID17: CONCRETE ON POWERHOUSE (2^ND STAGE) -> ID19: CONNECTION TUNNEL -> ID23: DISCHARGE TUNNEL (1^ST STAGE) -> ID28: OUTSIDE INSTALLATIONS -> ID18 CONCRETE ON POWERHOUSE (3^RD STAGE) -> ID24: DISCHARGE TUNNEL (2^ND STAGE) and then green crew leaves the Project, as shown in Chart 08.
 

Chart 08: Project planning using colors to identify crews rotation

Advantages

-       It doesn't only offers advantages of Gantt chart, but also describes perfectly crew movement through Project execution. If any changes happen during Project, planner can visualize exactly which will be the impact on manpower force planning, in case of added scope it is easy include these new works according to crew releasing and in case of reduction on scope it is also possible determine when the involved crew will be in stand by and to reassign them to another work station.

-       It is not necessary make a resource assignment in each activity if working on a planning software (MS Project, Primavera, etc.) to get the manpower’s curve.

For example if we change Chart 08 in order to have only crew life in the Project, not showing work stations, something like Chart 09 would result:

Chart 09: Crew life through Project

And if we drop down each bar on the horizontal axis as in Chart 10, manpower’s curve will show up immediately. For example, in Chart 10  we see the are two peaks in manpower’s curve, the highest is located just on the first quarter of 2011 and it is perhaps  the most crowded time of Project, because in this peak we have Light blue crew, Light gray crew, Green crew, Pink crew, Sky blue crew, Light red crew and Cherry crew working at the same time. 

Chart 10: Manpower's curve

Conclusions

-        Sorry, I couldn’t kill Gantt this time, but I’ll be back. I swear.

Reccomendations

-       The most recommended softwares to carry this out are those that offer several layouts for setting colors, for instance Primavera Project Planner, because we can use a first color layout to identify critical path, as usual; a second color layout to identify crews rotation; and a third color layout to visualize rotation of a critical resource we need to focus in, aside manpower.