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The Essential Elements of Modern Critical Path Method (CPM) Schedules

The type of schedule we most often recommend for your construction project is a CPM schedule. There are several elements you’ll see in every CPM schedule.

In technical terms, a CPM schedule models the project’s plan for construction in a network. This CPM schedule network consists of activities, which represent the project’s work scope, and logic relationships, which connect the activities to another, that together depict the project’s construction sequence and forecasts when the project will finish.

Critical Path

The critical path is the longest path of activities in the schedule network that forecasts when the project will finish. What does that mean? That means that everything we do has a critical path, whether it’s building a construction project, getting to work, or cooking Thanksgiving dinner. What the CPM schedule allows us to do is identify what that critical path is. It’s essential to properly identify the project’s critical path, because only delays to the project’s critical path will delay the project’s completion.

Data Date

Data Date Image

 

Every CPM schedule will have a data date.

The data date, which was the vertical blue line in the above screenshot, represents the date from which the schedule is calculated. Over the course of a project (as the project starts and the contractor makes progress), that vertical data date line will move forward in time.

If the CPM schedule is updated on a monthly basis, we’ll see that vertical line move 30 days forward in time every month. As the project progresses, all the activities

Construction Project Scheduling: A Basic Guide

In this basic guide to construction project scheduling, we’re going to discuss why we have schedules, why they’re important on projects, and how they should be used. In addition, I’m going to jump into and discuss essential Critical Path Method (CPM) concepts.

What Is Construction Scheduling?

A construction project schedule is either a written or graphical representation on how the project is to be completed or constructed. When I say written, it could be a written narrative. It could be a description. It could be depicted as a bar chart schedule or a CPM schedule.

A construction schedule is analogous to a contractor’s bid. Just as a contractor’s bid is an estimate of its cost that it expects to spend to build the project, the schedule represents an estimate of the time required to construct the project.

What Is A Construction Scheduler?

The construction scheduler is the person on the project who is responsible for developing and updating the project schedule.

There are really two types of schedulers. One is a button pusher, someone who takes the information from one party and inserts it in scheduling software like Primavera, Microsoft Project, or Asta Powerproject.

The second type is what I would call a professional scheduler. That’s someone who knows and understands construction means and methods, as well as the capabilities of the software. Most importantly, they also understand what construction scheduling best practices are and how to incorporate them into the project schedule.

Too often projects don’t have a professional scheduler who can pull all those elements together.

The Components of a Good Construction Scheduling Specification

Let’s talk about what goes into a good scheduling specification. Construction scheduling specifications can be fairly long and detailed. They often end up in the general provisions and can be the longest general provision in your specification.

A good scheduling specification will address:

  • Definitions
  • Administrative Requirements
  • Technical Requirements
  • Definitions of Key Terms

    If the scheduling specification uses terms that aren’t defined elsewhere, like critical path, I usually recommend that there be a definition of terms section at the beginning of the scheduling specification.

    Here are three key terms that I think are probably the most important related to a critical path method schedule:

    • Critical path
    • Longest path
    • Float

    That’s not to say there aren’t lots of other important terms. But, at the very least, these three terms should be defined.

    Administrative Requirements

    I also recommend that your scheduling specification address what we call administrative requirements:

    The Responsibilities of the Parties

    Your specification needs to clearly identify the responsibilities of the parties with regard to the preparation, review, and acceptance of the schedule.

    The Types of Schedules to be Prepared

    It needs to show the types of schedules that are to be prepared: initial schedules, baseline schedules, schedule updates, revised schedules, and recovery schedules.

    The Timing of Schedule Submissions

    It needs to identify the timing of schedule submissions:

    • How long does the contractor have before it must submit the schedule to the owner? • Does there have to be a schedule available at the preconstruction meeting? • Does the contractor have 30 days to submit the

    Should You Use Video to Document Your Construction Project

    A key objective of all construction documentation is to preserve a contemporaneous (prepared at the time), accurate, and factual record of what occurred on the project. And, frankly, the credibility of one document adds to the credibility of all your documents. Given the credibility of video, they not only serve to quickly and efficiently document important events, but they also enhance the credibility of all related documents.

    The nice thing about our phones these days is not only can they take great pictures, but they take great videos, too. I would not use video as a replacement for a daily log, mostly because it is very hard to access the information in a video (particularly if you have taken a lot of them). It can be hard to find the right video that has the right piece of information that you need quickly. But if you are performing potentially dangerous work or you are performing an unusual operation (an operation that perhaps involves multiple parties or could have catastrophic results), then it’s probably not a bad idea to be videotaping that kind of event.

    We worked on a project in Milwaukee where a large truss was dropped and someone was killed. It turned out that there were videos being taken by the general contractor. There was a video being taken by the steel truss erector. And there was a video being taken by a tourist who was standing outside the stadium. All of these videos were taken from different vantage points.

    The Best Use of Photos on a Construction Project

    You’ve heard the expression a million times. It’s a cliché. A photo is worth a thousand words. I say that and I must tell you there are dozens and dozens of situations I have been involved with where there is a great photo record, but nobody has any earthly idea what the photos are of, why they are significant, or why they were taken. The point here is that, yes, a photo is worth a thousand words. But most photos, if they have no words accompanying them, are virtually useless.

    Be like Officer Obe when documenting your project with photos

    When I talk about photographs, I am often reminded of the song, “Alice’s Restaurant.” Yeah, I have a couple of gray hairs. In that song, Officer Obe had taken twenty-seven, 8 x 10, color glossies and had annotated those pictures with circles, arrows, and a paragraph on the back explaining what they showed. Well, you don’t need 8 x 10 color glossies, and you probably don’t need circles and arrows. You may not even need a whole paragraph. But, wow, just a little bit of information goes a long way in terms of making a picture extremely valuable.

    I will give you the best example I have ever seen of pictures used effectively. We were working on a bridge project and the bridge could reasonably be split into two projects. On one side, concrete girders supported the bridge deck. On the other side, steel girders supported the bridge deck. On the concrete

    The Challenge of Notes to File on a Construction Project

    On a construction project, notes to file are often considered a form of communication. However, notes to file are not a complete communication. They are an incomplete communication.

    Why is that? Well, they are incomplete because you put the information to the file, but you didn’t share it with anyone else. So, it’s not really communication. You have communicated with the file, but you haven’t communicated with the party that might be affected by the note to file. There is nothing wrong with keeping track of what is going on and making notes to file. To some extent, a daily log is something like an organized note to file. By the same token, if the note to file is something that would cause someone to change their behavior, do the right thing, and help the project, then simply putting a note to file is not enough.

    Construction is not supposed to be strictly a “gotcha” game. We do want the other parties to pull their weight and execute their work as required for the project to finish timely, within budget, and to the appropriate level of quality. So, notes to file, while appropriate and useful in situations, are not communication. We should not anticipate or treat them as such.

    Why even use notes to file?

    What will we use notes to file for – to document unusual occurrences? I am sure that we could all come up with some good examples of what an unusual occurrence might be, like unusual weather, unusual meetings, unusual

    How to Organize Your Electronic Construction Project Documentation

    One of the things that can be quite helpful when we are using electronic documentation is to use a common nomenclature or structure. What do we mean by the terms “nomenclature” or “structure?” In other words, using consistent naming or numbering documents so they are easy to find.

    Let me give you an example. I do a lot of work for the Department of Veterans Affairs. On many projects that I’ve been involved with, the project documentation was organized by Request for Information (RFI) number. For example, if the contractor submitted a RFI, it ultimately led to a change order, and extensive correspondence between the parties as it related to that problem. All the information relevant to that RFI was stored in that RFI file, and it remained there until it became a formal change order. At that point, as the files were transferred to paper change order files, it ended up being a good system. Once you knew the issue and its RFI number, you could go to that RFI file and find anything related to that issue. On other projects, I have seen the documentation organized by specification number. In other words, how it related to a particular specification section.

    I have also seen it organized by a predetermined file structure, where the entire organization used the same numbering system. For example, you might find correspondence under file 1302.1 where 1302 was the project number.

    There is no standard organizational structure for documentation on a construction project. Each organization develops

    Criticism of the ASCE Schedule Delay Analysis Offsetting Delay Concept

    By Mark Nagata, PSP, CDT

    At the recent 2018 AACE International Conference and Expo, Mark Nagata presented his paper criticizing the ASCE Schedule Delay Analysis’s offsetting delay concept. The paper’s abstract is below.

    Abstract

    The American Society of Civil Engineers (ASCE) published its Schedule Delay Analysis Standard in August 2017. Not as ambitious as AACE’s Recommended Practice for Forensic Schedule Analysis, ASCE’s Standard is largely composed of concepts pioneered, proven, and standardized by others. However, the Standard includes an unproven concept – offsetting delay. Offsetting delay is controversial, both, because it is unproven and, because it is biased towards the interests of contractors.

    The concept of offsetting delay states that an owner may be required to grant the contractor a time extension for an owner-caused, non-critical-path delay at any point during the project. This aspect of the concept modifies what has long been one of the basic laws of time extensions – the contractor is only entitled to a time extension to the project completion date when an excusable delay delays the project’s critical path and forecast completion date.

    The ASCE’s concept of offsetting delay is biased against the interests of the owner because it provides a time extension for non-critical-path delays to contractors, but does not provide relief to the owner from the contractor’s delay costs in identical circumstances. This paper evaluates the issues of criticality, concurrency, the redefinition of key terms, and other aspects of the ASCE Schedule Delay Analysis Standard’s offsetting delay concept in arguing for its removal from the standard.

    Please

    16 Things You Need To Document On Your Construction Daily Reports

    Over time, we have developed a list of 16 items that should be documented consistently on every daily report. We are going to discuss each, but a good tip is to pull out your company’s daily report template and compare it to our list. Every company should have a daily report template and it should be used consistently across all of your projects.

    Furthermore, to get all the information you want on your daily report, make sure your report asks for it. If necessary, modify your report template to include a section of all 16 areas that we are about to discuss.

    Even before we get to our first item, and although this is obvious, the report must be dated and we also recommend including the day of the week as well. We see many reports that are incorrectly dated. Having the day of the week identified can help sort out which date the report was truly recorded on.

    Item 1: Weather

    Our first item that should be included is the weather. You want a complete weather report for the day. Was it sunny, cloudy, rainy, or snowing? What were the temperatures morning, noon, and at the end of the day? How did the weather change throughout the day?

    Item 2: The Location of Work On Site

    Who was working and where were they working? Location can be defined by sectors on the plans, column lines, or using north, south, east, or west directions.

    Item 3: Work Accomplished

    Who is performing what scope? In this section, it is

    Incorporating Weather Days into Your Project’s CPM Schedule

    An often-debated question is “How should a project schedule incorporate the workdays that might be lost to adverse weather?”

    While there is not one perfect solution for all projects, there are at least three approaches to incorporating weather into your CPM schedule. These approaches are:

  • Incorporating non-workdays into the schedule’s work calendars to represent the workdays that might be lost to adverse weather.
  • Increasing the durations of weather-sensitive work activities to represent the workdays that might be lost to adverse weather.
  • Adding an “adverse weather” activity at the end of project with a duration that equals the number of workdays that might be lost to adverse weather.
  • (Of course, there is always a fourth option, which is to assume that every day lost to weather will be made up by working on Saturdays or by working overtime. If this is the assumption upon which both your costs and your schedule are based, and both your contract and your other team members are on board, then you may not have to bake any weather into your schedule at all.)

    Each of these three options (except the one in which you do nothing to the schedule) will be discussed in more detail below.

    1. Incorporating Adverse Weather Workdays in Work Calendars

    In CPM scheduling software packages, users have to create or modify work calendars that identify when the contractor plans to work. For example, the most common work calendar is an 8-hour-per-day, 5-day workweek calendar that includes holidays and weekends as non-workdays. Each schedule activity is assigned to the work