Understanding Negative Total Float, Causes, Impacts and How to Manage It

Introduction

Project scheduling is the most challenging part of controlling timelines and ensuring that the projects are delivered within the specified time. Primavera P6 is a top project management software, and it allows the project team to determine when they are on track. Float is one of the most important calculations in CPM software as it tells how much schedule flexibility exists. A negative float is an indicator pointing at something wrong in the project plan and the project’s deadline will not be made. So, in this article, we will talk about the negative float in Primavera P6 and its causes, impacts, and how to manage it.

Definition of Float

 Before going through a negative total float, we need to know what float means. Float or slack is the amount of time an activity can be delayed before it causes delays to other activities or overall project duration.

There are two types of floats. The first one is “Total Float”, which is defined as several days an activity can be delayed without causing any delay in project duration; the second one is “Free Float,” which refers to the number of days an activity can be pushed without changing the start date of subsequent activities.

What’s Negative Total Float

A negative total float is when an activity finish date is set after a project’s completion date which means that it will cause delays in the overall project-required completion date. A negative float shows in primavera as a negative value indicating that one or more activities have an issue that needs resolution.

Common Causes of Negative Float in Primavera P6

Multiple factors can cause the negative total float to appear in your project schedule, such as:

• Project Constraints

Primavera p6 gives you the option to apply constraints such as “Mandatory Finish” or “Finish on or before” on activities, but if these constraints are incorrectly applied, they could cause an unrealistic timeline, which leads to a negative total float.

• Resources Constraints

When resources are overallocated, we usually use resource leveling to deal with this issue. However, resource leveling could increase the duration of activities beyond the completion date and cause total negative float.

• Improper Relationships Between Activities

Incorrect or unrealistic dependencies between activities may cause negative total float. For instance, if two activities are constrained by finish to start relationship while to start relationship could be applied, it could limit the flexibility of the project, leading to a total negative float.

• Calendar Mismatch

Each activity in Primavera is assigned a calendar; usually, it’s one calendar for the entire project, but if there are two calendars and they are inconsistent with each other or even mismatch between the project’s calendar and any activity’s calendar, such as one with fewer working days that could cause the total negative float to show in your project.

• Out of Sequence Activities

Out-of-sequence activities are the activities that are being performed out of logically planned order, like starting earlier or later than planned. When this happens, it may cause delays on critical paths, leading to negative total float.

• Changing Scope without Schedule Adjustments

Sometimes, the scope gets expanded along the way while the project is already in progress; if this happens and no adjustments are made to accommodate these changes, it could push the project beyond the completion date, resulting in a total negative float.

Impacts of Negative Total Float

In project management, a negative float serves as a warning that the project or certain activities are not going to meet its critical deadlines. There are a lot of impacts of negative total float some of them are:

• Project completion delays

As previously discussed, negative float indicates that there is one or more activities that could not meet the project completion date, which indicates potential delays that could lead to making the project behind schedule.

• Costs overrun

Project delays result in extended use of resources such as labor wages and equipment rentals; also, as a result of delays, contractual penalties may be applied. All these costs are added to the project’s budget, leading to budget overruns.

• Client and Stakeholder Expectations (Reputation Damage)

Failure to meet the project’s completion date the client is expecting can affect your company’s reputation, cause future opportunities, and cause client disappointment so you have to make sure to manage them and surely avoid any delays in any deliverables of the project.

Negative float is a great indicator that a project is on the path to having such problems, it is an early warning to take corrective actions and avoid any losses.

Steps to Fix Negative Float

Taking action to manage and resolve this negative float is an important step in schedule analysis. Below are a few ways to mitigate negative float

1. Periodic scheduling monitoring and controlling regular monitoring of projects is required to avoid negative float accumulation.
2. Adjusting Constraints: Review constraints that are causing negative floats and change them to resolve the issue.
3. Reviewing Relationships and Dependencies: activity relationships should be re-evaluated to make sure they are realistic.
4. Correcting Calendars: Ensuring that activity and project calendars are consistent.
5. Re-Evaluating Activity Durations: reviewing and editing each activity duration based on realistic time frames.
6. Adjusting resource allocation: If the negative float is due to resource allocation, managing or increasing resources will solve the negative float issue.

Tools and Techniques in Primavera P6 to Manage Float

Schedule Log Review: When running a schedule, you can view the schedule log, which identifies issues in the project under the warnings section. You could use this log to analyze issues that lead to negative float.

Analyzing Critical Path: Use a critical path filter to analyze and resolve negative float issues.

What-If Analysis: You can copy your project and create hypothetical scenarios on it where you can simulate delays or use different resource allocations and compare the results of different scenarios to identify the best approach to keep a positive float.

Conclusion

Simply put, a negative float in Primavera P6 indicates that your project is running behind schedule and will not meet its planned finish date. This can be due to multiple reasons, such as constraints, Calendar mismatch, scope changes, and resource constraints. Finally, the consequences of a negative float are severe, indicating that anticipated delays, cost overruns, and penalties associated with the contract (if applicable) may be triggered.

However, if a project is managed proactively and the project schedule is closely monitored, the negative float can be tackled. Project managers can, by adjusting constraints, compress the schedule, reallocate resources and monitor the progress regularly, minimize the effect of negative float, and get back the project on track. Proper float management is vital to getting projects done on time and within budget.