The five fatal flaws in your schedule…
…you will never discover with Gantt!
DO YOU SWEAR BY YOUR GANTT CHART?
OR YOUR Line of balance (flowline) diagram?
Either way – learning these five flaws – will make you an even better planner!
I’ll quickly show you what happens when you convert your Gantt schedule to a line of balance (flowline) schedule.
From Gantt to Flowline
Take a minute to look at the colored flowlines/activities (Ca, Ms, Pa, El).
When they are copied from the top schedule (Gantt) down to the bottom schedule (location-based), you can see what happens when these lines/activities are divided into locations:
– 2nd floor
– 1st floor
– Ground floor
When the lines/activities are split into locations – they change to the characteristic oblique lines – also known as flowlines.
These flowlines hold information about activity, time, and location.
E.g. On May 2nd, the carpenter and mason have activities on the 1st floor.
Buckle up; let’s get started and find the five fatal flaws.
Flaw no. 1
Colliding activities is the first flaw on the list.
In the flowline view, colliding works will appear where two flowlines intersect.
The result of intersecting lines is that more than one set of contractors/disciplines are simultaneously working at the exact location.
Depending on the activities, this may or may not be a problem.
The carpenter could install cabinets in the kitchen at the same time as the mason puts up tiles in the bathroom.
But if the carpenter is behind schedule, and the walls that the mason needs to put up tiles on in the bathroom, still need to be built, this qualifies as a problem. More often than not, colliding activities are causing waiting/wasted time on site.
When contractors waste time waiting for each other, they earn less money, making it challenging to keep a good tone. A “First come, first served” work environment can occur between the contractors on the site and becomes the basis for daily irritation.
Flaw no. 2
Several locations at the construction site are empty…
…at the same time as colliding and crowded places elsewhere…
Areas on site need to be used.
In the line of balance (location-based) chart, empty/unused locations will appear as significant gaps between the oblique lines. There are no planned activities in that location when there is a gap.
When locations are not included in the scheduling process, but only time and activities are, the consequence is both Flaw no. 1 and Flaw no. 2.
It will be more or less random which locations are crowded and which ones are empty.
The contractors work on locations – that happen to be empty that day. This random use of sites will cause interrupted and unsteady flow and waiting time in the activities.
This will significantly impact the contractors’ flat fee–and a good and healthy tone on site.
Flaw no. 3
Time wasted when waiting – ‘start and stop.’
Wasted time while waiting is a factor of great importance for the contractors’ workflow and earnings.
In flowlines, “start and stop” can be read as a broken line. As in the illustration above. The painters (yellow) have to find the courage – or the electricians (red) have to man down – to get a good flow between the two disciplines.
Random activities performed at random locations result in random waiting times. Especially in cases where critical dependencies between the disciplines occur.
Example. The mason can only put up tiles once the carpenter has completed the wall in the bathroom. There is a critical dependence between carpenters and masons.
If, in this case, there are fewer carpenter’s teams than masonry teams on site, the carpenters’ teams will work “slowly” in the workflow, compared to the masons’ groups who will perform “fast.”
This will cause waiting time for the masons. They can not access the location – until the carpenters are finished.
To resolve this issue, the carpenter’s team has to find the courage – or the mason’s team has to man down – to ensure a good workflow between the two disciplines.
Flaw no. 4
Uneven staffing and flow
A continuous number of teams from each discipline, starting at “number 1” and finishing at “number 100”, working in a constant flow with no interruptions and waiting time, is preferable.
Random use of resources/teams on site are essential factors for lack of consistency on site.
Example. The carpenters experienced, due to lack of planning, massive waiting time one day when they were six teams on site. They decided to send half the teams to another construction site nearby.
If resource/staff planning is an integrated part of the planning process, the consequence will be a construction site with consistency and disruption. Random teams on site, trying to get some work done, only to be shipped off to a different construction site the next day, are not contributing to a healthy environment and workflow on either site.
Flaw no. 5
Unable to overview consequences of delays
Once the schedule is made and the construction phase is ongoing, there will always be unforeseen factors that will affect the planned schedule. With Gantt, the consequences of unpredictable factors and delays in a specific location by a particular team are impossible to visualize and anticipate.
With a line of balance (flowlines), on the other hand, you can make forecasts / visualize the consequences of changes and delays. You can illustrate the implications for a specific discipline, a specific team, a specific location, resources concerning a particular section, dependencies between groups, and the deadline. All these consequences will be visible – in time to make corrections.
You can also reject “wishful thinking” at weekly meetings in the construction shed. Maybe you have experienced an example similar to this before:
The carpenter is delayed 14 days but reports: “Hey, don´t worry, we will make it before the deadline anyway.”
You can precisely visualize the consequence of his delay to the carpenter. So that you know, you will be able to do so in detail. The subsequent painter will not be able to meet his deadline on that specific location – at that particular time – due to this unavoidable delay. The overall deadline will also need to be completed.
You will also be able to visualize why his wishful thinking is just that and not realistic. With the number of men in his team, the speed he has worked with is envisioned as a thin green dotted line in the illustration above. Without manning up, the dotted line will follow its new path. The deadline will be delayed.
On the other hand, if he does find courage in time, the deadline will be met (illustration below).