Activities with open starts

Introduction

It is an activity that, although it has prior logic relationships, does not have a predecessor that effectively controls its start through a Finish to Start (FS) or Start to Start (SS) relationship.

In xerPlanner, this analysis identifies activities within the analyzed project that have at least one internal predecessor, but no internal FS or SS relationship. This means that the activity may be linked through Finish to Finish (FF) or Start to Finish (SF) relationships, but those relationships do not directly control its start.

This criterion helps detect activities whose start may be weakly controlled within the project’s logic network. If the start of an activity is not properly controlled, the activity may be allowed to start before there is a sufficient logical sequence supporting its execution.

When xerPlanner identifies that an activity reported as a finding may be controlled by external FS or SS relationships, it marks it with “[e]” before the Activity ID. This mark indicates that the case should be reviewed together with the external relationships section of the report, since the finding may depend on the context in which the XER file will be imported or reviewed.

The impact of open-start activities

Activities with open start may affect schedule reliability because they allow an activity to start without a sufficiently clear internal logical condition. Although the activity may have predecessors, if those predecessors only control its finish or establish a relationship that does not control its start, the beginning of the activity may remain exposed to incorrect interpretations.

For example, an activity may have a Finish to Finish relationship with another activity. That relationship may control that both activities finish in a coordinated way, but it does not necessarily prevent the successor activity from starting too early. In that case, the activity has a predecessor, but its start remains open.

This can create problems in project planning and control. An activity with an open start may be scheduled on an apparently valid date, but that date may not be supported by an appropriate construction, contractual, or technical sequence. As a result, the schedule may show a weaker logic flow than it appears at first glance.

The impact may also affect critical path analysis and float interpretation. If the start of an activity is not properly controlled, the logic network may allow unrealistic scenarios, reducing the reliability of the schedule as a tool for control and decision-making.

The following image shows an example of an activity that has a predecessor relationship, but whose relationship does not effectively control its start. This condition creates an open start that should be reviewed to confirm whether the logic correctly represents the expected project sequence.

Cases that should be interpreted carefully

Not every activity with an open start necessarily represents an error, but it should be reviewed. In some cases, the planner may have used a relationship other than FS or SS for a specific technical reason. However, if the objective was to control the start of the activity, there should be a relationship that effectively controls that start.

WBS Summary activities are not considered findings in this analysis. This type of activity can work correctly without its own logic relationships, because its start and finish dates are automatically adjusted based on the activities contained within the corresponding WBS.

Finish milestones are also excluded from this analysis. Since they represent a completion point, their relevant logic is associated with the finish, not the start. For this reason, they should not be evaluated under the same criterion applied to executable activities or start milestones.

There may also be activities whose start appears open when only the internal project relationships are reviewed, but which have external FS or SS relationships. In that case, the finding must be interpreted carefully. If the external project exists in the same database where the schedule will be used, the relationship may validly control the start. However, if the XER file is imported into a database where that external project does not exist, the relationship may not be available, and the activity would effectively remain with an open start within the analyzed project.

For this reason, xerPlanner does not automatically discard these cases. Instead, it reports them preventively and marks them with “[e]” so the user can review the associated external relationships.risk of certain activities starting without a properly modeled prior condition.

Best practices for managing open-start activities

To properly manage this type of finding, the first step is to review whether the start of the activity should be controlled by a previous activity, a milestone, a technical condition, or a contractual constraint.

It is also important to identify which types of relationships the activity has. If it only has FF or SF relationships, it should be evaluated whether those relationships truly represent the intended logic or whether an FS or SS relationship is missing to control the start.

In practical terms, the review should consider at least the following:

• Confirm whether the activity has internal predecessors.
• Review the logic relationship type associated with each predecessor.
• Verify whether there is at least one FS or SS relationship controlling the start of the activity.
• Evaluate whether the existing FF or SF relationships are sufficient to represent the real work logic.
• Check whether the finding is marked with “[e]” and, if so, review the external relationships section of the report.
• Confirm whether the external relationships will be available when importing the XER file into another Primavera P6 database.
• Correct the internal logic when the start of the activity should be controlled within the analyzed project.

By applying these reviews, the schedule gains logical coherence and reduces the risk of certain activities starting without a properly modeled prior condition.

Conclusion

Activities with open start can weaken the logical quality of a schedule when their start is not controlled by an appropriate relationship. Although these activities may have predecessors, if none of them effectively controls the start through an FS or SS relationship, the logic network may allow unrealistic scenarios.

In xerPlanner, this analysis is applied with a preventive criterion. It considers the internal relationships of the analyzed project, excludes WBS Summary activities and finish milestones, and marks with “[e]” the cases that may be controlled by external relationships.

Reviewing and correcting these findings helps strengthen the logical sequence of the schedule, improve dependency traceability, and reduce risks when working with files coming from different Primavera P6 databases.