## Overlap or Delay Tasks

Sometimes task links alone might not show accurately when tasks will actually start. For example, in the clockwork project, painting the walls precedes hanging the clocks, and those tasks have a finish-to-start link. The schedule shows that the clocks will be hung immediately after the painter finishes painting, but that’s before the paint has had a chance to dry.

You can fine-tune task links — and make sure you don’t gum up the clockwork — by using lag time and lead time. By using lag time, you can specify a waiting period, or delay, between the finish of a predecessor task and the start of a successor task. To avoid making the museum crew crowbar the clocks out of hardened paint, the exhibit planner should probably add lag time between painting the walls and hanging the clocks.

With lead time, you can overlap two tasks so that a successor task starts before the predecessor task finishes. The exhibit planner could assign one person to begin hanging labels soon after the first clock is hung.

After you enter tasks and assign dependencies to them, analyze your schedule and look for instances where you can apply lead or lag time. By using lead and lag time, you can make your schedule more accurate, and you may be able to shorten it as well.

You can express lead or lag time as units of time or as a percentage of the predecessor task’s duration. For example, the paint on the walls must dry for 1 day before clocks can be hung, so the exhibit manager can specify a 1-day lag between painting the walls and hanging the clocks. Or, if the electrician can begin wiring display cases after half the cases are installed, the "Install and position case lights" task can start when the "Install wood and glass cases" task is 50 percent complete, regardless of the duration of the predecessor task.

To add lead or lag time

1. On the View Bar, click Gantt Chart .

   To add lead or lag time to a successor task quickly, double-click the link line on the Gantt Chart and type the lead or lag time in the Lag box of the Task Dependency dialog box.

2. In the Task Name field, select the successor task you want, and then click Task Information .
3. Select the Predecessors tab.
4. In the Lag field, type the lead time or lag time you want, as a duration or as a percentage of the predecessor task’s duration.
   Type lead time as a negative number or as a negative completion percentage. Type lag time as a positive number or as a positive completion percentage.
   Use minute, hour, day, or week for the lead or lag time units. To specify elapsed duration, precede the time unit with the letter "e" (for example, edays for elapsed days). Elapsed days include weekends and other nonworking days.

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