pm-lotus by Howard Vaughan

Knowing the latest dates that we can start and finish tasks without impacting the overall project schedule is key to effective time management, especially for those projects where schedule is the least flexible component (see Flexibility Matrix).

Like the critical path itself however, Microsoft Project does not display this information by default. But we can easily set up the display options to reflect the late dates as in the example below:

Here’s how we configure this. First we display the critical path:

• From the menu, select View, Gantt Chart
• Then click the Gantt Chart Wizard button on the Formatting toolbar
• Select “Critical Path”, then Finish, Format It, Exit Wizard.

The critical path tasks are now visible in red. Next we set up the late schedule for the noncritical (blue) tasks:

• On the menu, select Format, Bar Styles
• Then click Insert Row to add a row just above the Critical Path display row (note that inserting a row at the top of the list may not work)
• Enter “Late Schedule” for the ‘Name’ and select your preferred bar styles for the ‘Appearance’ – (in the example above I used a navy horizontal line bounded by small triangles)
• Select “Normal, Noncritical” for ‘Show For … Tasks’
• Lastly ensure that you select ‘From’ “Late Start” and ‘To’ “Late Finish”
• Click “OK”

Now you should see the late schedule bars showing for the noncritical tasks indicating the latest each task can start and finish.

Useful Information

Showing the columns for Total Slack (the difference between the early and late dates) and Free Slack (how long a task can be delayed without delaying a sucessor task) as in the simple example above tells us the following:

• The critical path runs through tasks E, G, J
• The noncritical tasks have varying total slack
  • Tasks B, C, H, L have only 2 days, so are near critical and should be monitored closely for any slippage
  • Tasks A, K have 7 days
  • Task F can be delayed by up to 11 days before the project finish date is impacted
• Tasks B and C have zero free slack so any delay will immediately impact their successor tasks

Track the Slack

Knowing not only which tasks are critical and which are not, but also how much float or slack there is on each non-critical task, helps us prioritize work (according to slack value) and monitor trends in schedule variance (changes in slack week-to-week).

8 Responses to “Displaying the Late Schedule in MS Project”