If you wish to use ALICE to optimize the cost or duration of your project, the flexible formula feature is a powerful tool. Unlike traditional scheduling methods where the duration of a task or the amount of a resource is a static number, you can define formulas so that ALICE will calculate these amounts for you based on parameters such as quantities, production rates, crew counts, or any custom property. We call this making a task flexible.
The benefit of making tasks flexible is that it enables automated optimization and scenario exploration. Users can change the parameters and ALICE will automatically propagate the changes across the entire schedule.
With flexible formulas you can:
- Explore the impact of production rates on schedule, cost, and duration
- Explore the impact of crew, equipment or material availability on schedule, cost, and duration
- Incorporate custom properties (user defined fields) into schedule simulations
In this article, we will cover the technical details of how to create formulas in ALICE Optimize for task duration or resource assignment.
Static and Flexible Values
Before we begin, it is important to discuss the difference between static and flexible values.
- Static values are simple numbers that represent the amount of time allocated for a task or the amount of resources assigned for a task. For example, a duration of 3 days, or a crew assigned value of 4. Most traditional planning uses static values.
- Flexible values are unique to ALICE. Users can create a formula based on parameters such as number of crews, production rate, or equipment available, and ALICE will calculate the values as part of the scheduling algorithm.
- In ALICE, users can work with static values, flexible values, or a combination of both
How to use Flexible Formulas:
Fields on the Plan page that support flexible formulas:
- Remaining duration
- Crew amount
- Equipment amount
- Resource amount
To assign a flexible formula:
1. Navigate to the Plan page and double click on the value you want to modify:
Click a value in the remaining duration column to assign a duration formula.
Click a value in the crew, material, or equipment column to assign a formula for resource assignment
Tip: Formulas can be added one task at a time, or bulk applied to many tasks at once. To bulk apply a formula to many tasks, check the tasks you want to update and then double click on the value you want to modify.
2. Build the formula. Click the blue "i" icon to open the formula sidebar. Read the Building a Flexible Formula section below for full details.
3. Input the formula and click save.
If you are creating a task duration formula, toggle to the 'formula' tab and input your formula.
If you are creating a resource assignment formula, you can input it directly into the amount field:
Note: when updating the variables that are used in a formula, the user needs to manually re-schedule the plan using the re-schedule button in order to get updated values.
Building a Flexible Formula
Formulas are created using variables and algebraic operators and input directly into the desired field on the Plan page (duration or resource amount). The variables must be formatted in snake case, and there is a formula sidebar to assist you in the formatting.
Use the Formula Sidebar to Find Variable Names
The formula sidebar allows users to find the names and syntax of variables for a flexible formula.
To access the sidebar, click the blue "i" icon visible at the top of the edit pop-up modal for remaining duration, crew, equipment or materials.
The sidebar will quickly allow you to find the available variables that can be used for building formulas.
Variables that can be used in a flexible formula:
- Any custom property
- Equipment, material or crew quantity
- Imported or current task duration
- Production rates
- Crew data such as workforce limits, BLUs, crew size
Click the name of any variable to copy it to your clipboard. From there, you can paste the field into the desired field on the plan page.
In the formula sidebar, all of the variables are formatted in snake case. Snake case is a format which replaces spaces and hyphens with underscores. This format is required for compatibility with the ALICE scheduling algorithm. As long as you use the duration formula sidebar to pull the names of variables, you will not need to further modify the formatting.
Algebraic operators
Basic algebraic operators are supported as follows:
- Multiply using *
- Divide using /
- Sum using +
- Subtract using -
- Parentheses ( ) can be used to define order of operations.
Flexible Task Durations
Users can make a task duration flexible by inputting their desired formula into the remaining duration field on the Plan page.
Duration formulas only operate on not started tasks. For in progress or completed work, durations must be static (numerical, not formula-driven). Duration formulas cannot be input for milestones or completed tasks.
Tip: To view the duration formulas for all tasks on the Plan or Analyze page, you can add the column "Remaining duration formula". This allows you to quickly see the underlying logic driving the remaining durations.
Rounding up Durations
When creating a duration from a formula, you may end up with a value that should be rounded up to the nearest whole number or other defined interval. Users can automatically round up task durations in the table view settings menu (from the Plan page, right click, select 'edit table view' and select 'settings'.).
Users can input the desired interval to be used for rounding up when using duration formulas, crew ranges, or running an acceleration scenario. For example, if the duration is set to 8 hours, durations will round up to the nearest 8 hour increment (8, 16, 24, etc). To round up to the nearest whole hour, input 1.
The round up feature will only operate on durations calculated by ALICE. If a user manually inputs a task duration, it will not be rounded up.
Other areas of ALICE where formulas are supported
In addition to Plan page, users can input formulas in the Excel export file, to be imported back into ALICE as an updated plan.
Formula fields are currently supported in the Task tab in the column labeled duration equation, and in Task Equipment and Task Material tabs in the required amount column. The same formatting rules apply: snake case and standard algebraic operators are supported.