The issue of float can be rather complicated. Many of the articles below are very technique. The goal for this class is to get a preliminary understanding of this issue. Article 7, Who should own the float, by Ron Winter (not Ron White), is the required reading for this week. This particular question has been asked over and over again in past years. Read Article 1 for an earlier take of this question. If you are interested in the technical aspect, you can start with Article 5. Article 6 is similar to Article 5. I also like Article 2. It is from a while ago but by a well-known author. The language is clear and precise. I wish I can write like that. The rest (Article 3, 4, and 8) deal with different aspects of the float issue.
Schedule compression is a closely related subject but I couldn’t find any suitable material for the class.
- Who Owns Float?, Gordon G. Peterman, CCE, Cost Engineering, Vol. 21, No. 02, 1979
- Float Ownership: Specs Treatment, Dr. Gui Ponce de Leon, PE, Cost Engineering , 1986
- Schedule Density as a Tool for Pricing Compensable Float Consumption, Michael Ross Finke, Cost Engineering , 2000
- Effect of Multiple Calendars on total Float and Critical Path, Nestor J. Scavino, CCC, Cost Engineering , 2003
- Total Float Management for Delay Analysis, Khalid S. Al-Gahtani; Satish B. Mohan, AACE International Transactions, 2005
- Total Float Management, Renovating a Misused and Abused Approach, Dr. Anamaria I. Popescu, PE, AACE International Transactions, 2008
- Who Should Own the Float, Ron Winter, PSP; Timothy T. Calvey, PE PSP, AACE International Transactions, 2008
- When is the Critical Path Not the Most Critical Path?, Murray Woolf, 2008 AACE International Transactions, PS.07, AACE International, Morgantown, WV, 2008
Part 1:
ReplyDeleteWhen is the Critical Path Not the Most Critical Path? by Murray Wolf slowly became a very interesting article and possible one of the more enjoyable one’s this semester for me. The gist (not sure I am going to do this article justice trying to describe what he wrote) of the article is that the nomenclature needs to be changed because the definition(s) of critical path are fuzzy at best and many projects have numerous milestones, etc. that may have multiple (near) critical paths that muddles the idea of the critical path. The author states everything is critical in the schedule if you want to complete the project on-time. Wolf’s hope is this article may persuade the scheduling profession to adjust definitions, define new ones, and clear up the confusion experienced in the industry. I think he does a commendable job at laying the ground work for this.
Early on he defines what path is and realizes the dictionary term does not do it justice to what path means or is supposed to mean in ‘critical path’. We have to account for all the components that collectively make up the path. We have to understand activities, durations, date constraints, relationships between the activities. Wolf believes the definition should make reference to the path’s point of terminus, as well as its point of origin; that leads to the question, “Where does a path begin and end?” If you cannot define this, how can you define the critical path? Wolf provides three options.
1) Open ends - begins where it has no predecessor activity, and it ends where it has no successor activity.
2) Date Constraints - assume that a start-no-earlier-than date constraint is imposed to the first activity in the schedule and that a finish-no-later-than date constraint is imposed to the last activity.
3) Total Float - path can only have one total float value, and that the start and end of a path are identified by a change in total float values.
Wolf tests each of the three options with a logic diagram and applies the two prevailing critical path definitions. These are longest-path and least-float basis. In each case he finds conflicting matters. Ultimately he defines path segment as “any series of connected activities that begins with either a date constraint or two or more predecessor activities, and ends with either a date constraint or two or more successor activities” (PS.07.3). This leads him to define ‘path’ as a series of connected path segments sharing the same total float value and terminating at a completion milestone” (PS.07.3).
He follows a similar method in coming up with definitional criteria for ‘critical.’ He considers the question, “is the path critical do to the activities on this path or whether the activities derive their urgency because they are on this path.” Is total float an activity or path variable? It is interesting if you start to think about it for some time. Almost has a philosophical aspect to it.
Part 2:
ReplyDeleteHe goes onto to define critical path and highlights why there are misunderstandings about it based on three scenarios where the project contractual length is 365 days, with 100 activities and the critical path contains 20 activities is he presents. At first I was confused by each of the scenarios he describes. The main point is how can the longest/least-float path be under 365 days in one scenario but over 365 days in the next and each are still considered the critical path. Somehow Scenario 3 does not seem as critical as the other two when it is ahead of schedule. This demonstrates the flawed thinking behind the word, “critical.”
He concludes the basis for determining the critical-path, it should not be comparative. The notion of one critical-path (whether the longest path or the least-float path) is a theoretical concept, but rarely the case in real life. The longest path basis for determining the critical-path is flawed, because of the common use of internal start-no-earlier-than and finish-no-later-than date constraints. The least-float path basis for determining the critical-path is flawed in that it necessarily ignores all but the path with the “least” float (PS.07.5).
In the second half of the article he delves into why new terminology should be created by others but presents some of his own ideas. He lists in Figure 1 New Naming Paradigm for Paths Transecting Schedule, Critical Path, Watch Paths, and Free Path. Critical Path has 4 sub-categories of Unrecoverable, Ominous, Grave, and Significant. Watch Path has 4 sub-categories as well, moderate, limited, probable, and possible. Free path has no sub-categories. These are intended to show increasing degrees of potential or actual impact to the timely achievement of more than one specific completion milestone (PS.07.7)
In conclusion it appears that Wolf has potentially created a path (no pun intended) for the AACE to take this issue seriously and reshape the definition of critical path so individuals in the profession can discuss more accurately what is happening during multi-deadline schedule instead of the longest path or the least-float path. At first I thought he was attempting to reinvent the wheel but instead he provides analysis of a key item in the construction industry that might be due for an update.
DS
Float Ownership: Specs Treatment, By Dr. Gui Ponce de Leon, PE
ReplyDeleteThis article is describing the possible language the mat be used to eliminate conflicts of float ownership before they happen by inserting language in the specifications. The language is rather legal in nature which makes it hard to decipher. The main point of the article is to illustrate how the specifications can be used to eliminate or greatly reduce the misuse of certain scheduling techniques.
There were several new concepts in this article for me, “float as bar”, “preferential ties”, and “float suppression”. These terms were a little difficult to understand in such a short article. However, the legal case cited offer a minimal understanding of the terms and how the courts have viewed them.
• Float as bar: I understand this to mean, the float is described as a bar of time to be used to decrease or increase the length of the bar when determining delays or changes. The article is written toward claims, but could also be applied to changes in the work.
• Preferential ties: the imposition of sequencing to reduce or increase float.
• Float suppression: this is a group of techniques including preferential ties.
The result of these techniques has important time extension implications. Is the contractor due a time extension to maintain the float established in his schedule? Is the owner entitled to use the float in making changes or decisions?
When we first discussed the idea of ownership of float this semester, I thought I understood who should own it. This was first talked about with the right to finish early (RTFE) of the contractor. After reading this article, I was mistaken and my view point has changed slightly. I now believe the contractor has the right to finish early but cannot use the float to their sole benefit. The early finish is a way a contractor can potentially save on GC’s and make more than originally contemplated. The float time established between the early finish and the contract date cannot be used to determine additional GC’s for the contractor but may be used to grant a time extension based on the approved early finish schedule.
The article concludes that the courts have been sympathetic to the owners position related to delay claims, however the specifications should also be written to include specific definitions of how the float is to be allocated to the parties of the contract.
Required reading: Who Should Own Float
ReplyDeleteThis article describes presents the debate of who owns the float in a construction project schedule; the Owner or the Contractor? The authors present their opinion that the float is actually owned by the first party that legitimately needs and uses the float to their advantage.
The article states that current laws side with the contractor’s interpretation of “ambiguous” contract clauses because of the fact that the owner drafted the contract and usually is written in the Owner’s favor.
The contractor still needs to communicate to the owner and is required to provide written notice within a short time period of the event that impacted the work.
I have never had any experience with the concepts of float in a high production home building environment. Since the cycle time of the construction of our houses is generally very short (60 to 120 calendar days), there is generally no float in the schedules that we produce other than weather delays. Even these are limited and we always find other alternatives to ensure that our houses are constructed on time. There are occasions when the houses are not built in the time frame established due to extenuating circumstances. However, the sales agreements we sign with our customers simply state that we will estimate a completion date and that we are not contractually obligated to that date. But we make every effort possible to complete the home in the time period we describe because of the other extenuating activities (mortgage closing, moving vans, enrolling children into the schools, etc.) and to achieve our objectives of satisfied and happy customers.
Steve Nellis
Who Should Own the Float? By Ron Winter, PSP and Timothy T. Calvey, PE PSP, is pretty straight forward and I agree that float should not be owned either by contractor or owner but rather used by the first party that legitimately needs to use it. They proceed to give reason why it is not a great idea to give either party ownership of the float.
ReplyDeleteEarly on in the article I found it odd that the owner would try to word the contract in favor of them owning the float. That does seem unfair and bit absurd that the owner would even attempt to do this let alone a contractor agreeing to it. Maybe all bets are off in a recession though?
I believe we have covered the activity float being consumed in three ways. Obviously the first two are by the owner or contractor and third is by uncontrollable third parties, force majeure or Acts of God, which would not surprise me if they start to become more prevalent in years to come.
The authors describe that owners can use float to change scope, failure to perform duties in a timely manner, interference etc. which all seems bogus reasons to use float. On the flip side the authors describe contractors who try to use float based on their actions or inactions to perform work properly, subcontractors and supplier’s inactions or actions, lack of a realistic schedule, etc. which again seems to me to be bogus reasons. These all sound like excusable or inexcusable delay claims and/or time extensions. In addition the authors cites ‘games’ that contractors play like changing project history and using artificial activity durations that are disappointing to read when both sides main goal is(or should be) to complete a project on-time and on-cost and try to build a productive working relationship, hopefully for repeat work. Reputations take years to build and can be ruined in hours or days by fudging items like this.
The portion of the article that dealt with if the contractor owns the float was interesting when it described if the float should appear in the baseline schedule or should it be day-to-day float? The authors feel this is serious once a delay occurs because the more the project is delayed the more float the contractor acquires which would leave much less incentive in mitigating delay. This leads to a brief discussion on ‘joint ownership of float’ and using milestones that might be the most effective way to handle float, delays, and additional costs.
Near the end the authors discuss the means and methods argument where the contractor can claim the owner interfered with the means and methods plan. This assumes that the contractor has created a detailed, minute-by-minute, hour-by-hour, and day-by-day work plan at the time of bid. This seems highly unlikely to the authors as well as to me. To me this sounds frivolous, maybe as silly as an owner making a delay claim against the contractor doing work in a busy downtown city street and accusing the crew of being distracted by attractive women walking by on and off all day that is causing delays.
Ultimately, if there are items that require essential (installation/delivery) times using milestones would help each side reach that goal. It sounds similar to the argument that Murray Wolf makes in When is the Critical Path Not the Most Critical Path? By redefining what a critical path is and is not in today’s complex projects that utilize milestones will help, just as understanding that float should not be treated as your get out of jail for free card for unreasonable mistakes and delays made by either side.
DS
Who Should Own the Float?: This article raised some interesting questions about the ownership of float, which as a residential contractor, I have had little formal experience with. It did seem to me however, that these authors’s were heavily biased “against” the contractor. The float issue has never been formalized in any of my projects but has always been an intuitive function of my job scheduling. If the project end date is not impacted, float has always been anyone’s to use. If the owner has delayed the project, I have never charged per say for the delay but it has allowed the completion date deadline to be pushed back – sometimes for a considerable amount of time, as his inaction may have created a chain reaction which is sometimes slow to recover in a residential job.
ReplyDeleteMr. Winter and Mr. Calvey talk about the legal “default” ownership of float which essentially says, it belongs and is free, to all parties. Their position that it is silly for a clause which states the contractor owns all the float, to me reinforces their bias. Depending on the particular project and conditions, it may be appropriate for the contractor to own it all. It may be appropriate for the owner to own it all. It just depends on the particulars; who has the most control of, and liability, in the schedule timeline. As a contractor, I find their position a bit naive and offensive.
Their descriptions of the uses of float by owners and contractors were right on the money. Essentially the owner can use it up by not making decisions on time, changing the scope of work, interference, and the owners representative doing the same thing. The contractor can use it up by poor job performance, poor sub-performance, and lack of a realistic schedule. Their description of a contractors schedule “games” was also offensive. Perhaps these guys had a bad experience with a contractor, but they obviously have not had a lot of experience with professionals. His description of third party float issues was also right on. Sometimes things happen that are no one’s fault and would not reasonably be allowed for. Some of his examples of things a contractor would claim for a time extension (which he inferred were unreasonable) seemed very reasonable to me, so we are definitely not seeing float ownership from the same lens. For example, continuous RFIs for things in plans & specs, blocking access to the job, excessive phone calls (I have had a few clients who pushed the envelope of reasonableness), architect clarifications, and rejecting schedule updates would be things as a general contractor, are wasting/taking my time. Is the owner not responsible for this?
I am really very much in disagreement with the author’s perspective on these issues. He goes on to talk about how the more a project is delayed (by owner?), the more float the contractor owns. I don’t see the unreasonableness of this. Some of his examples were a bit much, such as the fire truck. If it is the contractors fault, he should be penalized, if it is the owners fault, he should be compensated. I can only assume that these guys must have gotten burned by a very clever and dishonest contractor, or were severely penalized by a very good contractor for their own incompetence.
http://www.hartfordbusiness.com/news21291.html
ReplyDeleteThought with items we have spoken about over the past several weeks and months this article called Partnerships changing design-build industry fits right in.
DS
Effect of Multiple Calenders on Total Float and Critical Path: This article made a relatively simple concept rather complicated. As the author stated multiple times in the first page of his paper, “the use of multiple calendars eliminates or at least diminishes the most clear and easy way to visualize the critical path throughout a schedule, which is with the total float of the critical activities”. This is not a concept I have much experience with. I do some calendar scheduling, but only use one calendar –usually the five day work week variety. Mr. Scavino talks about the confusion that can arise from using multiple calendars as they relate to the critical path and float. This seems like a fairly intuitive observation; mix a few five day calendars with a seven day calendar – things will not line up. The float will have overlap in one and may come up short in the other. The critical path becomes much harder to follow and float becomes much harder to evaluate. I wasn’t very clear on why there would be multiple calendars on a single project. Is this something that is routinely done?
ReplyDeleteI was barely able to follow his examples. They make sense; I just felt they were rather poorly written. For example the following sentence: “In the specific case of the two activities analyzed here, the finish milestone and its predecessor testing the conversion from calendar days, in the plain calendar, to working days, in calendar 3, can be estimated by the following method”. – huh? I got the concept and I believe the author to be an authority on the subject. I was just not very impressed with this author’s writing skills in explaining the complexities of trying to incorporate multiple calendars on a single project and how it can add to the confusion of where the critical path lies and how much float actually exists (and who it belongs to).