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Resource leveling in PRA

4 replies [Last post]
Alexandre Faulx-B...
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Joined: 20 Jan 2003
Posts: 1347

Hello planners,

Where could I find some comprehensive documentation about the nudge and resource leveling process in Primavera Risk Analysis?

Having tried to level the same project in P6, MS Project, Spider and finally PRA, I find that PRA does not reschedule the project the same way as the 3 others.

Thank you



Critical Chain method is about creating and managing buffers.

If you want to use buffers that are defined as the result of risk simulation then it is not Critical Chain Project Management method but Success Driven Project Management method:

It can be used with any software that can calculate probabilities of meeting project targets.

But as I wrote earlier PRA and P6 use different leveling algorithms and with limited resources PRA calculations can not be applied to P6 resource constrained schedules.

Alexandre Faulx-B...
User offline. Last seen 2 weeks 2 days ago. Offline
Joined: 20 Jan 2003
Posts: 1347

Thank you both,

could the PRA resource leveling algorithm include some part of the Critical Chain method?


David Kelly
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Joined: 19 Oct 2004
Posts: 612

Vladimir is correct, everyone uses a different method, there is no documentation describing how any of the Primavera products do this. It is  as proprietary in the way that the critical path analysis with a forward and backwards path is public domain

The correct methodology is the Minimum Moment Matrix solution as extended to a three dimensional matrix to allow for a priority ranking for resource fit, as written by me in about 1985. But you will need a working Data General mini computer. I couldn't do the maths anymore.


every PM software uses its own leveling algorithms. So the results of resource leveling by different tools and the resulting planned sequence of activity execution may differ. Even the same PM software produces different schedules if to use different leveling priorities.

That is why it does not make sense to use any external software including PRA for risk simulation of resource constrained schedules. They create probability distributions for management that uses their own planning rules, not the rules that are used by the initial package.

If you need correct risk management for resource constrained projects use Spider Project for both resource management and risk simulation.

Best Regards,