Modeling and Recovering from Delay Impacts with ALICE

Users can model any potential, or actual, delay and generate schedules that will resequence the remaining work in an effort to mitigate the impact. ALICE supports modeling these delay types:

  • Task and milestone delays
  • Availability delays
  • Force Majeure delays

 

Types of Construction Delays

Task and Milestone Delays

Task and milestone delays are localized to a particular activity, scope of work, or project milestone within a project schedule. It is possible to model discrete delays in ALICE using constraints that are applied to specific tasks or milestones.

Examples:

  • Permitting approvals
  • Site preparation
  • Design changes
  • Utility connections
  • Inspections
  • Testing and commissioning
  • Handoffs
  • Rework
  • Change orders

Step By Step:

  1. Identify all tasks or milestones that relate to the delay being modeled
  2. Either,
    1. Apply a mandatory start constraint to the selected tasks (if it’s a milestone, this can already be controlled in the milestones tab in the create a new scenario window on the explore page)
      1. Note: it may be the case that only one task or milestone needs to have a constraint applied in order to accurately model the delay
    2. Create and add a production rate to the planned duration formula of the task(s) that are experiencing the delay setting the Qty/Hr to “1” [this will only work for when modeling with tasks as you cannot alter the duration formula for milestones]
  3. Run scenarios exploring the range of delay severity desired using the rates or milestone tabs, depending on the application chosen in step 2,  to select various delay amounts

 

Availability Delays

An availability delay is a period of time during which a required resource for some portion of a construction project is unavailable. Utilizing ALICE’s resource, calendar, and constraint functionality, the availability of resources that are required for performing select work can be accurately modeled and controlled to model an availability delay.

Examples:

  • Crew mobilization
  • Material deliveries
  • Labor shortages
  • Site access restrictions
  • Funding

Step By Step:

  1. Create a new task that will represent the period of time that a resource (ex: electrical subcontractor) is going to be on site
  2. Create a new material which will control the scheduling of tasks that require the resource being delayed
    1. When creating the new material, set the Type to “Reusable”, Qty. Avail. to “0”, and $/Unit to “1”
  3. Apply the new material to the new task
    1. Set the Action to “Supplies” and the Amount to “100” (or any number larger than the possible maximum number of concurrent tasks to be performed by the delayed resource)
  4. In Edit data in Excel, pull every task that is impacted by the delay and assign the new material to it with each task requiring “1” unit
  5. Set the new task calendar to a 24 hour calendar
  6. Set the duration of the new task to be at least as long as the expected duration the resource will be on site
  7. Set a mandatory start constraint to be the forecasted on-site (or mobilization) date of the resource
  8. Run scenarios exploring the range of delay severity desired using the milestone tab to select various on-site (or mobilization) dates

 

Force Majeure Delays

A force majeure event delay is caused by unforeseeable circumstances which any party involved is unable to predict, control, nor mitigate. Modeling dynamic delays that completely halt all or a portion of the work that is ongoing on a construction project can be done using dummy tasks, material supplies, production rates, constraints, and special logic ties.

Examples:

  • Pandemics
  • Natural disasters
  • General weather days
  • Terrorism or war
  • Government regulations
  • Economic crises
  • Strikes or civil unrest

Step by Step:

  1. Create a new task that represents the period of time between the start of the project and before the force majeure event happens (the “before” task)
    1. Create another task that represents the period of time the event is occur (the “event” task)
    2. Create another task that represents the period of time after the event (the “after” task) until the end of the project
  2. Set the task calendar to a 24 hour calendar for all the new tasks
  3. Create a new material which will control the scheduling of tasks (in this case completely halting of some or all work) that are impacted by the event
    1. When creating the new material, set the Type to “Reusable”, Qty. Avail. to “0”, and $/Unit to “1”
    2. Add this material to the “before” and “after” tasks and set the Action to “Supplies” and the Amount to “1000” (or any number larger than the possible maximum number of concurrent tasks to be performed by the delayed resource)
  4. In Edit data in Excel, pull every task that will be impacted by the event and a assign the new material to it with each task requiring “1” unit
  5. Create and add a production rate to the planned duration formula of the “event” task setting the Qty/Hr to “1”
  6. Set a mandatory start constraint on the “during” task to its planned start date
  7. Tie the “before” task to the “during” task with a FS relationship
    1. Tie the “during” task to the “after” task with a FaS relationship
  8. Run scenarios exploring the range of delay severity desired using the rates tab to control the duration of the force majeure event and the milestone tab to set the start date of the event

 

Further Resources

Primary Constraint Types in ALICE

How to Create Production Rates

How to Create Materials

How to Create Tasks

How to use Edit data in Excel

Running Scenarios

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