Linking activities

In a schedule, activities are usually connected to define their execution order.

A link creates a logical relationship between two activities called:

• predecessor: activity that must occur before
• successor: activity that depends on the previous one

These relationships allow the schedule to update automatically when an activity is modified.

To link two activities in the Gantt chart:

1. Select the two activities in the desired order while holding the CTRL key and right-click
2. Select Create link
3. Choose Link two activities

A link editing window will then open.

In this window, you can define:

• the predecessor activity
• the successor activity
• the link type
• a possible lag

Once the parameters are defined, confirm with OK to create the link.

Several types of relationships can be defined between two activities.

The most common types are:

• FS – Finish to Start

the successor activity starts when the previous activity finishes.

• SS – Start to Start

both activities can start simultaneously or with a delay.

• FF – Finish to Finish

both activities must finish at the same time.

• SF – Start to Finish

the successor activity must finish when the previous activity starts.

The Finish to Start (FS) type is the most commonly used in project schedules.

It is possible to add a lag between two linked activities.

This lag can be expressed in:

• elapsed days
• or working units

A lag can represent for example:

• drying time
• a logistics delay
• a waiting time between two operations

The Create link menu also allows faster creation of relationships in certain situations:

• Link a sequence: automatically creates links between several selected activities following the schedule order.

• Link multiple activities: allows several relationships to be created in a single operation.

These tools help quickly structure the scheduling logic.

An existing link can be modified at any time.

To do this:

1. Select the activity in the Gantt chart
2. Right-click and choose Edit
3. Access the different links in the Links tab of the editing window

You can then adjust:

• the relationship type
• the lag
• the predecessor or successor activity

From this tab, it is also possible to add links from the Predecessor or Successor tables:

In some projects, additional constraints can be defined between activities.

These constraints may include:

• a minimum geographical distance
• a minimum time separation

These parameters are particularly useful in linear projects where several teams operate along the same alignment.

They help ensure a safe distance or a minimum time separation between two operations.

Links form the calculation logic of the schedule.

Once activities are connected, the software can:

• automatically recalculate dates
• analyse task dependencies
• identify the impact of delays
• ensure the consistency of the schedule

A properly linked schedule therefore becomes a true project management and control tool.