Bad weather is difficult to predict and can be a significant source of schedule uncertainty. Adverse weather is an important consideration in the planning of a project.
Inclement weather is a common risk on outdoor projects. The temperature dropping below 32°F can put a stop to concrete installation efforts. Rain and snow can shut down all outdoor work for days or even weeks. Bad weather is a real risk on outdoor projects and very hard to predict. Deltek Acumen Risk supports including adverse weather as a risk event in its schedule duration uncertainty analysis.
This article demonstrates how to include adverse weather predictions in Deltek Acumen Risk’s Monte Carlo schedule duration analysis.
The National Oceanic and Atmospheric Administration (NOAA) provides bad weather data to support the generation of a monthly adverse weather forecast. This data includes temperature, rain, and snow predictions by region. All this data may be combined to formulate the predicted monthly adverse weather days.
It is beyond the scope of this article to demonstrate the process retrieving, combing, and formatting NOAA temperature, precipitation, and snowfall data into predicted regional adverse weather tables. What is generally included in government contracts is a monthly forecast of adverse weather similar to Figure 1.
This table provides the monthly forecast of adverse weather days by region. This is the expected delay in days resulting from adverse weather, which combines the effect of temperature, rainfall, and snowfall. This table is the starting point in our effort to demonstrate how to model bad weather related schedule duration uncertainty in Acumen Risk.
We have in Figure 2 our demonstration Primavera P6 Professional project schedule.
This schedule mainly consists of three activities with Finish to Start (FS) relationships. The deliverables include demolition, installation, and quality assurance of piping. The schedule has a single point deterministic completion date of April 12th, 2019.
We begin our demonstration by importing the XER file of this project into Acumen, Figure 3.
We then choose to import all projects into the current workbook, Figure 4.
Continuing, Figure 5, we save the workbook.
Now we are ready to consider risk. We select the S3 // Risk tab, Figure 6, to begin the process of analyzing project risk.
We want our duration uncertainty factor to include seven settings. To set this we select the uncertainty icon, Figure 7.
Then we adjust the uncertainty factor to seven, Figure 8.
In Figure 9 we set the duration uncertainty to extremely conservative, which specifies that the activity duration estimates are likely to be met or better.
We proceed and set the risk analysis to uncertainty only and no risk events, Figure 10.
We want to first examine our schedule without any risk events. We run a Monte Carlo analysis of the schedule using 1000 iterations. The results are displayed in Figure 11.
As expected, our schedule met or beat the April 12th, 2019 deterministic analysis.
Now we are ready to define our adverse weather risk event. Select the risk register, Figure 12.
Click to add a risk event, Figure 13.
Type in the name Adverse Weather and set the type to calendar event, Figure 14.
Exchange panels to edit the risk event probability distribution, Figure 15.
First disable all periods then select April, which is the month we execute our schedule. The 100% probability is good. As per Figure 1, April is anticipated to have 7 adverse weather days. Insert the triangular probability distribution minimum 6-days, most likely 7-days, and maximum 7-days, Figure 16.
Acumen allows for leeway in the triangular probability distribution. We chose to set the most likely and maximum to the anticipated 7 adverse weather days for April. In Figure 17 we confirm the mappings to activities.
We again exchange panels, Figure 18.
We are now prepared to analyze our schedule uncertainty and include the adverse weather risk event, Figure 19.
In Figure 20, we run a risk analysis.
The final results are displayed in Figure 21.
Our schedule has a 59% possibility of meeting the deterministic April 12th, 2019 completion date. The worst case scenario now indicates an April 19th, 2019 completion date. So our adverse weather risk event has an impact on the project completion date. There is also a 75% probability of the weather delaying completion by 2 working days. We would do well to plan on the adverse weather delaying the completion date by 2 working days.
Adverse weather is hard to predict and can have a significant negative impact on schedule duration. In Deltek Acumen Risk, adverse weather is modeled as a calendar event. Schedulers input the minimum, most likely, and maximum weather related delays for each month, including the probability of occurrence. In this way schedulers can model the potential adverse effects of bad weather on schedule duration.
Deltek Acumen Risk also supports modeling other risk events and mitigation efforts to provide for a schedule that is thoroughly risk vetted and managed.