Real-World Project Modeling in Aurora That Supports RDM & RDCPM Functionality

The Relationship Diagramming Method (RDM) & Relationship Diagramming Critical Path Method (RDCPM), both developed by Fredric L. Plotnick, Esq., P.E., introduce powerful concepts designed to improve transparency, logic clarity, and throughput in project schedules. When supported by project management software, these concepts can significantly enhance real-world modeling accuracy. However, most project management tools do not fully implement these advanced capabilities.

Aurora intelligent scheduling and project management software is different. In reviewing the practical application of RDM/RDCPM concepts, it becomes clear that Aurora supports many of the critical functionalities required for real-world project modeling. Aurora’s modeling capabilities were developed directly in response to client needs. These features were not theoretical additions—they were built because real-world users recognized their value and invested in their development. As a result, Aurora delivers measurable, real-world benefits.

Contiguous and Concurrent Relationships (CT & CC)

RDM & RDCPM define both contiguous (CT) and concurrent (CC) relationships.

• Contiguous (CT): requires tasks to occur back-to-back with no gap between them
• Concurrent (CC): requires two or more activities to occur at the same time (fully or partially overlapping)

Aurora supports these concepts through its support of absolute Finish-to-Start (F=S) constraints, which is synonymous with RDM’s CT relationship, and RDM’s concurrent relations is supported in Aurora via Aurora’s constraint by the same name. 

In addition, Aurora also supports non-concurrent constraints.

• Non-concurrent (NC): defines activities that are not to overlap in time, but otherwise may be completely unrelated.

In real-world Aurora applications, the NC constraint is used far more frequently than the CC constraint.

These capabilities allow schedulers to accurately represent work that must proceed continuously versus work that may have a gap; as well as correctly modeling tasks that must be performed at the same time and others that must not be performed at the same time as one or more other tasks. By modeling these distinctions precisely, project teams gain clearer visibility into how activities truly interact, eliminating ambiguity that often exists in simplified scheduling tools.

Continuous and Interruptible Activities

Real projects rarely follow a single pattern of execution. Some tasks must proceed uninterrupted, while others can pause and resume. Aurora supports both continuous and interruptible activities, enabling schedulers to model field conditions realistically rather than forcing artificial constraints.

This distinction improves accuracy in schedule forecasts and supports better decision-making when interruptions occur due to weather, resource availability, or other real-world factors.

Risk and Monte Carlo Analysis

A key strength of RDCPM concepts is understanding uncertainty within schedules. Aurora supports Monte Carlo analysis, including fully resource-loaded models with sophisticated modeling capabilities.

By incorporating risk simulation directly into detailed schedules, teams can evaluate probable completion ranges instead of relying on deterministic finish dates. This provides a more transparent and defensible approach to schedule risk analysis, which is particularly valuable in complex or high-stakes projects.

Complex Calendars and Shift-Based Constraints

Real-world projects operate across multiple calendars, shifts, and constraints. Aurora supports complex calendars and shift-based constraints, ensuring that activity durations reflect actual working conditions.

To further refine how work aligns with these schedules, Aurora includes configurable shift control properties that determine how jobs interact with shift breaks and resource availability.

• Ensures a job only starts if it can be completed within the same shift.
• Restricts certain jobs to be performed during the day shift only.
• A job can take multiple shifts, but requires the same resources (e.g., same people, equipment, etc.).

Event Codes and Sub-Activity Modeling

Aurora supports extensive user-defined fields, such as the creation of Event Code Start and Event Code End data structures. When event codes are required within an activity, the activity can be divided into sub-activities connected by absolute Finish-to-Start (F=S) constraints.

This structured approach preserves logical clarity while allowing advanced tracking of event codes inside broader tasks—aligning closely with RDM principles.

Passage Versus Progress

One of the more nuanced RDM concepts is the distinction between passage of time and actual progress. Aurora’s default offset lead/lag capability satisfies the passage version of “overlapping activities.”

When modeling progress-based relationships, sub-activities linked with F=S constraints can represent specific amounts of work required for completion. A separate constraint can then tie a specific amount of progress to dependent activities. This allows the schedule to reflect true work progression rather than simply elapsed time—an essential feature for accurate real-world modeling.

Reason/Why Constraint Codes and Justification Fields

Transparency is central to RDM. For physical constraints, Aurora allows the reason/why to be entered directly within the constraint definition through its justification field.

This ensures that constraints are not just applied but documented. The result is improved auditability, clarity in claims environments, and a stronger schedule defense.

Aurora’s support for a subset of the Relationship Diagramming Method and Relationship Diagramming Critical Path Method in Aurora demonstrates how real-world project modeling can align with advanced scheduling theory. Every capability described above was developed in response to practical demands from real-world project environments. The outcome is software that supports much of the RDM/RDCPM functionality, and proves the benefits of these capabilities in complex project environments.

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