Customer Reviews

Precedence and Arrow Networking Techniques for Construction

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This book is one of the best construction scheduling books in term of quantitative analysis. The book does a good job on explaining the fundamental concepts of construction scheduling and further the concept to calculation part. Every concept is presented with examples and solutions, which are very useful. The contents of the book are:

1. Introduction. This chapter gives readers background in general about construction scheduling (such as resources, network, bar chart, and schedule).
2. Project Breakdown. This chapter is about deciding, preparing and organizing information (such as level of detail, activity data and constraints).
3. Basic Arrow Diagramming (or Activity On Arrow, AOA). This chapter is all about how to construct an arrow network (activities are represented by arrow shapes). If you don't plan to do manual calculation, he might want to skip this chapter. Moreover, commercial software these days does not use arrow diagram (AOA) anymore. However, redundant link, dummy activity (which is very tricky for AOA) and how/when to use dummy activity are well explained in this chapter.
4. Basic Precedence Diagram (or Activity On Node, AON). This chapter presents how to construct Precedence Diagram (AON) and show step-by-step how to eliminate redundant link.
5. Establish Activity Durations. This chapter is 5 pages long. However, I never read it. :P
6. Scheduling Computations for Arrow Networks (AOA) and 7. for Precedence Networks (AON). These chapters focus on the calculation of both types of the networks. The author shows how to use network diagrams (drawings) and how to use table (like spreadsheet but manually calculate) to calculate activity properties (such as early start date and floats). Formula for the calculation is well explained along with many examples. In both chapters, four types of floats and their formula are presented according to the type of the network (AOA and AON). In addition, the concept of using matrix (another kind of table) to update total float (TF) and free float (FF) is presented in the chapter 7. This matrix becomes handy when manual calculations of updating TF and FF are required. (You better get familiar with this matrix if you want to study one of the unlimited resource leveling concepts called Minimum Moment Method, explained later in chapter 11)
8. Communication the Schedule. This one is more like "How GUI of scheduling software (such as report format and bar chart) looks like 30 years ago". Surprisingly, nothing has changed much from today software. What a shame.
9. Project Control. This chapter discusses level of control, setting target scheduling, monitoring project, evaluating and forecasting project, control period, and updating project progress. This chapter shows you what can be done in term of project management and scheduling according to the knowledge discussed in previous 8 chapters. Moreover, it also guides readers to a new topic, Time-Cost Tradeoff.
10. Time-Cost Adjustments. This chapter presents the concept and the calculation of time-cost tradeoff analysis during pre-construction phase. The idea of varying crew sizes associated with their direct costs is discussed. A good example is used to demonstrate the idea and also the application of Fondahl's technique. Besides the concept of time-cost tradeoff which is well explained, I am not a big fan of Fondahl's technique because it is very tedious, error prone, and not guarantee an optimal solution. I suggest you to read the concept and try to use EXCEL to optimizing a time-cost tradeoff problem. Moreover, the author does not discuss cash flow analysis.
11. Resource Leveling. This is one of my favorite chapters since I am so into "resource leveling". This chapter discusses two different types of resource leveling which are Limited Resource Allocation and Unlimited Resource Leveling. For limited resource allocation, a traditional method (very simple and used in most commercial software) is explained. For unlimited resource leveling, the author uses an example to show how to level (reducing the fluctuation in resource required per day) unlimited resource by using Minimum Moment Method (MOM). Later, he furthers the leveling concept of single resource to multiple resources, and also demonstrates how to schedule activity so that the schedule will accommodate resource constraints. In brief, the author did a good job in this chapter compared to those in other scheduling books. Since this book was written in the early stage of construction engineering and management, the concept of leveling resources for multiple projects and the idea of leveling resource and still maximize resource learning curve are not discussed. In addition, later the author developed a new unlimited resource leveling called PACK which is more effective and less computational effort than MOM. Unfortunately, PACK method is not presented in the book. Last word about this chapter, MOM and PACK are most likely to outperform those resource leveling features some commercial software.
12. Program Evaluation and Review Technique (PERT). PERT is a probabilistic scheduling method that calculates chance of finishing project within a particular period. This book as well as many other books probably say the same thing and show how the calculation of PERT. So, nothing is special. However, I would like tell you that these days we use simulation to get the same information from PERT with less pain. However, if you are old school, please read a method called Probabilistic Network Evaluation Technique (PNET). PERT only considers the longest path while PNET considers the longest path and other high independent paths with high variation in duration. Since variation exists in activity duration, the longest path may not always the critical path (hmm this sounds confusing).
13. Overlapping Network. From chapter 1 to 12, activity dependency is only described as finish-to-start relationship. This chapter introduces new types of activity constraint: start-to-start, start-to-finish, finish-to-finish. Formula and an example (which is enough) are used to explain the idea of overlapping network.
14. Selected Application. I never read this chapter since it is 30 years old.

The only major thing that is missing from this book is a scheduling concept of linear scheduling. Since this book was published when construction was not interested or not really appreciated the idea of maintaining resource utilization, eliminating resource idle time, the concept of scheduling linear project or repetitive project (such as high-rise buildings and highway projects) were not presented. Besides that, this book is an excellent book with cost of $60.

This is one of the best, perhaps the best, construction scheduling books available in the market. The book contains all important contents in this issue. The book is very easy to understand, therefore ones without knowledge in scheduling can understand readily. Moreover, it contains several advanced topics in scheduling, including PERT, overlapping networks, and time-cost tradeoff. The author, Robert Harris, is a well-known pioneer in this field and has been a professor teaching scheduling classes at the University of Michigan for many decades. I strongly recommend this book for everyone who wants to own an excellent scheduling book.