Lag and Lead Time in the Forward and Backward Pass (continued)
Whereas lag time adds to the schedule, lead time subtracts from it. In the following example, it has been decided that Pour Concrete can start while Mix Concrete is being done. Again, notice the arrow. Using the forward pass, 2 days would be subtracted from the EF of Mix Concrete to calculate the ES of Pour Concrete. The formula is EF - lead time = ES of the next activity.
Using the backward pass in the following example, you would add the 2 days of lead time from the LS of Pour Concrete, 6, to get the LF of Mix Concrete, 8.