Activity Network Diagram — the urban engine - EU-Vietnam Business Network (EVBN)

Estimating both time required and sequence of operations is important in management. The Activity Network Diagram is commonly-known in form but rarely defined and analysed. It is also known as an arrow diagram, and gained popularity with other management techniques during the 1960s Japanese boom of industrial engineering and operations research.

The Activity Network Diagram is a planning technique.

The Activity Network Diagram technique is effective because it is methodical and systematic, creating a plan that is persuasive and robust. It is also simple to use and interpret making it useful for rapid decision-making. It can be used in all forms of commercial, scientific and civil fields for problems ranging vastly in field, size and complexity. It is intuitive and agnostic of experience and cultures.

Mục Lục

Requirements:

Given a complete understanding of the activities which are required to be completed in order to achieve some objective, an Activity Network Diagram can produce:

Various time estimates for how long a project may take,
Indications of the relative importance of certain steps, and
Clarity of dependencies and efficiencies as both risks and opportunities.

An objective can be any simple or complex need which an interested party is attempting to fulfil – the design of a product, building of a house, passing of legislature etc. An activity is the more granular constituent process work – analogous to milestones, components, steps or tasks.

All activities which constitute the objective must be previously enumerated, defined and understood. Sufficient context and a thorough and empirical understanding of the problem is necessary for success. An agent (or agents) is required to generate, administer and extract value from the Activity Network Diagram.

Mechanics:

An Activity Network Diagram is essentially a directed graph. It has nodes which represent activities required in completing some predefined and well-understood objective and edges (arrows) which indicate moving from one completed activity to the next.

Process:

Exhaustively enumerate all activities required in the completion of some objective.
Identify and familiarise oneself with the resources available to complete this objective.
Estimate how long each activity may take in a specified time metric (e.g. minutes, hours, days) based on the resources available.
Estimate a tolerance (upside and downside) in a specified time metric for each activity for the best- and worst-case based on the resources available.
Arrange all activities on a surface.
- Contingent activities should be laid out in series by chronological order.
- Non-contingent activities which can be performed in parallel given resources are sufficient to facilitate this.
Bookend the diagram by adding a start and end node.
Identify the critical path which is the longest path from the start node to the end node. It should encompass all unique in series nodes and the longest of each layer of parallel nodes. This can be indicated by a bold or overlaid line on the diagram.
Determine estimated project times:
- Most Likely Time (most accurate) – adding up all time units on critical path
- Optimistic Time (best case) – adding up all time units on critical path while subtracting tolerance for best case
- Pessimistic Time (worst case) – adding up all time units on critical path while adding tolerance for worst case

Limits:

The Activity Network Diagram technique has a large reliance on the competence, experience and capability of the agent(s) using the technique. Commitment is also required to ensure that there is no authoritarian domination of the analysis and that no pre-existing biases cloud the outcomes. There is also no objective way to guarantee good ideas are generated or that they will be exhaustive. Similarly, the generation of activities is often obvious but is entirely arbitrary from a deductive perspective. When used without awareness of these limitations and strictness in the process, it can be completely ineffective.