Critical path and elapsed days! How does it works?



I will show you different behavior in MS PROJECT 2010 in Critical Path when you have, and when you do not have Elapsed days in duration fields!

Suppose that you have three Tasks and each of them has one day duration and they are connected:


I will apply Tracking Gantt View to see Critical Path:


and then:


Finally, I will get:


You can see that all three Tasks are on Critical Path. Why? Because Critical Path is Path which can have no delays. That means if any task is behind the schedule (late), the whole project will be late. So Task1 one should start at 11.07.12 (from 08:00 till 17:00 with one hour for lunch), Task2 should start at 12.07.12 (from 08:00 till 17:00 with one hour for lunch), and should start at 13.07.12 (from 08:00 till 17:00 with one hour for lunch)!

Now suppose that Task 1 has duration 1ed (1 elapsed day, e.g. 24 hours):


Everything is the same! Task 1 will start at 11.07.12. at 08:00 and will finish at 12.07.12 at 08:00 (24 hours). That looks fine! But what if I have Task2 with duration 1ed instead of Task1?


Task 2 is no more on the Critical Path! How can it be? Is this an error? No, not at all!

I will put some more columns in my Tracking Gantt View: Early Start, Early Finish, Late Start, and Late Finish:


The Explanation:

  • Early Start: Task 2 has Early Start immediately after Task 1 is finished, and that means it can Start at 11.07.2012, at 17:00 (5:00 PM).
  •  Early Finish: Task 2 has Early Finish 24 hours (1 eday) after Early Start, and that means 12.07.2012 at 17:00 (5:00 PM)
  • Late Finish: Task 2 has Late Finish just before Task 3 must start, and that means it can Start at 13.07.2012, at 08:00 (08:00 AM).
  • Late Start: Task 2 has Late Start 24 hours (1 eday), before Late Start, and that means 12.07.2012 at 08:00 (8:00 AM)

The conclusion? Tasks 2 has Slack or Float!

Float is Late Start – Early Start = 12.07.2012 08:00 AM – 11.07.2012 05:00 PM = 15 hours or Late Finish – Early finish = 13.07.2012 08:00 AM – 12.07.2012 05:00 PM = 15 hours

And since Task 2 has a Slack or Float it is NOT ON THE CRITICAL PATH, because on Critical Path Tasks have Float or Slack = 0!



About Nenad Trajkovski

Location: Zagreb, Croatia Occupation: Project Manager Interests: Project Management and MS PROJECT He was born in Zagreb, Croatia at 1963. After completing his college he started working on projects in different business areas (banking, manufacturing, automotive industry, distribution, oil companies, etc.) developing and implementing ERP systems into different companies. He has got a lot of experience working with people in different business processes and also possesses great knowledge in information technologies and financial services. Today he works as a business consultant, adn Project Manager in PERPETUUM MOBILE d.o.o. Zagreb. He is a regular lecturer for Project Management in MS Innovation Center in Varaždin, Logosoft Sarajevo in Bosnia and Herzegovina and SEAVUS GROUP in Skopje Macedonia. He was named the best lecturer of WINDAYS 2008 while his lecture was also voted as the best. In addition, he was in TOP 10 lecturers at the MS SINERGY 2009 and MS VISIA 2009, 2010. Shares first place as the best lecturer of KulenDays 2009 and 2010 and PMI Conference 2009 in Zagreb. He is also a regular lecturer in the MS Community. He is a Certified Accountant and a PMP (Project Manager Professional) and a PMI-RMP (Risk Manager Professional), MCP, MCT, and Microsoft Certified Technical Specialist - Microsoft Project 2010. From 01.01.2012 awarded with MVP (Microsoft Most Valuable Proffesional - Microsoft Project)!
This entry was posted in MICROSOFT PROJECT, Microsoft PRoject 2010, MS PROJECT 2010, PMI, PRoject Management and tagged , , , , . Bookmark the permalink.

6 Responses to Critical path and elapsed days! How does it works?

  1. WK says:

    Hi there.

    I think you have a great website educating others on the MP. Keep up the spirit of sharing. I need your help on a schedule i am currently working on. I am actually analysing the critical path of the project and in the options, i have set the critical path criteria as less than or equals to zero.

    1. How do i set the final completion date of a project? I think it is not quite possible.
    2. In my schedule, the activities with total slack of less than zero (e.g. -1 or lower) do not actually delay the entire project. I actually tested it out by moving the activity later and it have no influence on the final completion date. Why?


    • Nenad Trajkovski says:

      1. If you know exact finish date of your project, you should build you project schedule from that date. That mean that you should go to Projecct Tab, Project Information button, and choose Schedule from: Project Finish date, and then add this finish date!
      2. IT depends. I can not tell anything before I see your Project. Send me an mpp file to


  2. Dana C. says:

    Thank you for sharing this! I’m in school for MS Project Management. Very easy to understand. 🙂

  3. Vinay Kumar V says:


    I was searching the net and stumbled upon you blog, where you share your knowledge on project management and MS project. I have been following your blog for the last few weeks.
    I have to say that every topic is succinctly written to make the learners understand them easily. The blog covers pretty much all the topics in MS project and Project management. It is a very good learning resource for learners and practitioners alike.
    All I have to say is “THANK YOU” for sharing.

    Vinay Kumar V

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