Members,

I’ll start of thanking anyone in advance for reply to my post below.

This started as a discussion between my boss and I, in respects to a TIA (time impact analysis) and what should we monitor against, either Dates (Early start/finish) or TF (Total Float), we both had different views.

Total Float

I have always conducted and reviewed TIA based on the impact to the critical path, the method is, progress the programme to the point of the delay – record the TF of the progress of the works.

If the progress of the works as pushed the TF into a critical reading (I.E. TF Equal to or less than 0) then it would be assumed that the Progress has delayed the project (lonest path).

When inserting your delay (fragnet) and linking correctly, splicing it into place, schedule the programme and record the TF.

What one would hope is that the TF would be moved more than the Progress TF.

Then it’s a simple Progress TF – Delay TF which would give you the potential EOT.

(I’ve kept this as simple as I can for this request)

Dates

Same as above, but this time rather than record the TF values, you capture the dates (early Start / Finish) then dump this data into excel (excel would calculate on a 7d working week) and a simple calculation of Progress date – Impact date = EOT.

I have asked two people about the above and each one has picked one of the above, leaving me still a bit miffed as what is correct and what would suite best any scenario.

One reply which did make sense was, normally the programme is not built in a way of which true reflection of critical path can be ascertained. Contractors change links, lags and other tricks to hide their progress delays. So this is why the date method on TIA is more robust.

The other reply, which concurs with my thinking is that, is a programme is accepted by the client or employer, then it is accepted will all links, logic, sequence, lags and constraints, regardless. Hence the acceptance of the programme, surely he runs checks on it ??…it is after all a contractual binding docuemnt.

The critical path is key to project success and thus we should always (with my planners hat on) monitor critical path, additionally TF less than or equal to 5, TF less than or equal to 10. This will help give better “early warning” indicator and secondary CP for review and analysis.

Also float plays a part, free and total float – an item can in fact have zero TF but 5 days free float, meanign you can push this activity 5d before it would register a minus delta.

So can someone please help my brain out and give me your thoughts on the above, it might help to know, one of the people I asked was a friend of mine who wrote the contract we are working against !! the other is a very highly respected consultant who owns his own company dealing with claims and arbitrations.