Forward Pass and Backward Pass calculations

I need to calculate something called a certain dates using something called Forward Pass and Backward Pass Methods(see below). Using the table(found at the link at the bottom) as an example (however macro needs do calculations using the lastrow with data inputed for the range).

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This is perfect for a custom object.
The attached uses a custom object clsActivity

It has read write properties
Name
ExpectedDuration
ProjectTargetFinish
ActualStart
ActualFinish

read-only properties
Duration
ActualDuration
EarliestFinish
EarliestStart
LastFinish
LastStart
PreceedingActivities
SubsiquentActivities

and methods
PreceedingActivitiesAdd
SubsiquentActivitiesAdd

The demo doesn't use the actuals. The demo takes the raw data (name, precedent action, expected duration, project target) from A:D
and outputs the calculated properties in G:L

Hi Kid,

I can't see your dropbox - did you remove it?? But Mike's sophisticated solution looks to be excellent!

To run it hit Alt + F8 and choose the macro named test and click on run.

*as mike has said the input must be in columns A:D

.

Thanks so much for all the previous Help. You guys have been amazing

I've been thinking and there's a situation that confuses me.
In my workbook, there are two processes "sew pants" and "sew shirt" that have to be completed before "box suit" is started. It doesn't matter what order and neither the pants nor shirt is necessary for the other.
BUT, if the company has only one sewing machine, they can't be done simultaneously and "When many activities lead into one activity in the Forward Pass method, chose the highest EF date to calculate the ES date for the succeeding activity" doesn't work.

In your attachment, the activities and their precedents were set up wrong.
Each activity/precedent pair is on one line, the ExpectedDuration and the ProjectTargetFinish should be on the first line for that activity.
Also, I noticed that you removed the ProjectTargetFinish. How does one calculate the LastFinish given that the LastFinish of the last activity is the Target deadline for the project.