Setting up critical chain scheduling

Summary: Choose how LYNX-X shortens task durations and sizes buffers for a project, and insert the buffers into the plan.

Applies to

Property	Value
Product	LYNX-X
Version	28.10.9800.0
Required permissions	Read and write access to the project
Last updated	2026-08-26
Owner	Support

Before you start

The project needs a plan with connected tasks. See Adding tasks to a project plan.
The project must be Not started. Duration shortening cannot be changed once the project is Released — see Troubleshooting.
If the terms critical chain, buffer or shortened duration are unfamiliar, read Understanding the critical chain first. This article covers only the settings.

Procedure

Open the settings

There are two ways in. They open the same dialog, so use whichever is closer to hand.

Route	Steps
From the project	Select Properties, then the Critical chain tab.
From the toolbar	Select Open the CCPM property dialog box in the CCPM group.

The CCPM group sits in the toolbar and holds three buttons. It appears only while the project is Not started.

The CCPM group in the toolbar

Both routes open the same dialog.

Project properties, Critical chain tab

Choose how durations are shortened

Select Automatically detect and mark critical chain tasks so LYNX-X works out which tasks form the chain.
Select Automatically shorten task durations.
In Shorten durations by (%), enter how much of each estimate to remove. The protection you take out here is what the buffers give back.

Size the buffers

In Feeding buffer(s) (%), enter the size of a feeding buffer as a percentage of the branch it protects.
In Milestone buffer(s) (%), do the same for milestone buffers.
In Project buffer (%), enter the size of the project buffer as a percentage of the critical chain.

TipThese percentages decide whether the project also finishes earlier. Set the buffer to give back roughly what Shorten durations by (%) took out, and the total duration stays about where it was — you get buffer management without renegotiating the date. Set it lower, and the buffered plan comes out shorter than the original, which is a commitment as well as a plan. See Understanding the critical chain.

Insert the buffers

Select Insert buffers.
Select OK.

TipReevaluates project buffers, the first button in the CCPM group, does the same job from the toolbar — it inserts the buffers, or updates them if they already exist. Remove buffers, beside it, takes them out again.

Expected outcome

The plan gains rows that are not work: a project buffer at the end of the critical chain, and a feeding buffer wherever a branch rejoins it.

Task durations are reduced by the percentage you set. Compare a duration against what you entered to see the shortening — LYNX-X does not mark shortened durations with any symbol of their own.

A planned project, with its feeding buffer and project buffer

Additional information

NoteExpected buffer consumption (%), under Project execution on the same tab, is not a planning setting. It describes how much of a buffer the project is expected to have used by the time it completes. Once work is under way, LYNX-X weighs actual consumption against chain progress to work out CCPM priority — neither number means much on its own.

Note Only the project and milestone buffers act as the controlling buffer. A feeding buffer protects the chain from a late branch, but never drives the project's CCPM priority.

Tip Set these before the project is released. Changing how durations are shortened rewrites the plan underneath anyone already working to it.

Troubleshooting

Problem	Resolution
The CCPM buttons are missing from the toolbar.	The project is Released. The group appears only while the project is Not started.
The duration options are greyed out.	The project is Released. The dialog says so at the top: "Some fields cannot be changed when the status is set to 'Released'". Set the status back to Not started to change them.
Insert buffers is not shown.	The same reason — it appears only while the project is Not started.
Buffer percentages can be changed but nothing else.	This is expected. On a Released project the buffer sizes stay editable while the duration options do not.
No buffers appear after selecting Insert buffers.	The tasks are probably not connected. LYNX-X cannot find a chain, and therefore cannot place a buffer, until the plan has dependencies.

On a Released project LYNX-X states which fields it has locked, and the two groups behave differently.

The Critical chain tab on a Released project

Revision history

Version	Date	Author	Changes
1.0	2026-08-26	Support	Split from How a plan becomes a critical chain, keeping the procedure. Both routes to the dialog documented. Released-project behaviour tested rather than assumed.

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