METRICS FOR PROJECT SCHEDULE PERFORMANCE

ABSTRACT 

The development of project planning is a challenge for any construction professional. Some planning leads to erroneous results because of an erroneously formulated development. These errors are not only fatal in the tendering phase, but represent an even greater problem during the monitoring phase of the projects, both of which lead to critical assumptions. This is further worsen when such programmes are used to analyse risks, indirect costs, sensitivities, alternatives, etc. 

To try to mitigate this, there are proposals to assess the formal structure of a schedule by means of checklists that set certain limits on the formal structure. 

We will point out the main metrics recognised by the industry to determine whether a plan has major flaws or whether it indicates a reasonable forecast. We thus address the correlation between current metrics and the development of a reasonably structured plan. 

INTRODUCTION 

The development of a certain planning associated with a construction project is a tool that can be used to forecast aspects such as the execution plan, completion date, progress, milestones, resources, duration of activities, sequence and costs. This will require, among other things, that the planning be appropriately structured and composed. 

Many construction projects experience impacts, delays or faulty forecasts that have their origin in faulty planning.  

We consider a planning to be defective when its formal structure or scope is incompletely flawed, making it impossible to forecast completion dates, resources, costs, ….. When developing a plan, different sources of information are usually used: the project contract, plans, specifications, personal and project experiences and education, all of which are used to develop the structure and scope.  

With the development of an adequate formal structure in mind, some organisations, public entities, private firms, software companies and consultants have developed checklists or guidelines that evaluate the formal structure of a schedule. Even though there is no unified criterion, we will try in this document to identify a list of metrics, recognised by the industry, that will serve to determine if a schedule has a reasonable formal structure and in this way help the schedules to offer a reasonable forecast, always bearing in mind that what is audited is the formal structure and not other fundamental aspects when developing a schedule, such as: performance, number of teams, calendar, sequences, ….. 

The following steps were taken to draw up the list of metrics:  

  1. Literature review and analysis 
  1. Compilation and selection of metrics 
  1. Metric analysis… 

LITERATURE REVIEW AND ANALYSIS 

There are different metrics to verify the quality of the formal structure of a planning. As a result of our experience in international projects, we have carried out a review of the most important guidelines and practices we have come across and searched the literature. The organisations and literature consulted are listed below: 

  1. DCMA (Defense Contract Management Agency) – Earned Value Management System (EVMS) Program Analysis Pamphlet (PAP) (2017) – (https://www.dcma.mil/Portals/31/Documents/Policy/DCMA-MAN-3101-02.pdf ) 
  1. AACE – Total Cost Management Framework: In Integrated Approach to Portfolio, Program, and Project Management (https://web.aacei.org/resources/publications/tcm ) 
  1. U.S. Department of Defense – The Program Managers’ Guide to the Integrated Baseline Review Process (2015) (https://www.ndia.org/-/media/sites/ndia/meetings-and-events/divisions/ipmd/links-and-reference/intergrated-baseline-review-guide.ashx?la=en ) 
  1. GAO – GAO Schedule Assessment Guide: Best Practices for Project Schedules (2015) (https://www.gao.gov/products/gao-16-89g ) 
  1. NASA – Schedule Management Handbook (2020) (https://www.nasa.gov/sites/default/files/atoms/files/nasa_schedule_management_hand_book.pdf ) 
  1. Naval Air Systems Command Program Success Orientation Team – Integrated Master Schedule (IMS) Guidebook (2010) (https://www.dau.edu/tools/Documents/PMO%20Situational%20Awareness/Resources/NAVAIR%20IMS%20Guide.pdf) 
  1. NDIA – Planning & Scheduling Excellence Guide (PASEG) (2019) – (https://www.ndia.org/-/media/sites/ndia/meetings-and-events/divisions/ipmd/links-and-reference/paseg_v4-final2.ashx ) 
  1. PMI – Practice Standard for Scheduling (2019) (https://www.pmi.org/pmbok-guide-standards/framework/practice-standard-scheduling-3rdedition ) 
  1. University of Texas – Design and Construction Standard-Division 01 General Requirement Specification Section 01 32 00 – Project Planning and Scheduling University of Texas: Office of Facilities Planning and Construction (2021) (https://pmcservices.utexas.edu/DCS-division-01-general-requirements ) 

COMPILATION AND SELECTION OF METRICS 

From each publication referred to above, we compiled the guidelines and metrics that will serve to analyse the formal structure of a planning, so that we can generate a list of possible guidelines to consider, marking the recommended thresholds in those cases where their application has a positive impact. In this way, some of the metrics included in the literature have been included due to: 

  • The metric is not commonly used in the international projects we have developed. 
  • The metric did not have a recommended threshold in the researched literature. 
  • The metric was not appropriate for analysing a benchmark programme. For example, earned value was not considered in the evaluation. 

However, it is logical that some of the metrics do not have recommended thresholds as they are necessary for the basis of other metric analyses. However, these metrics were not included because they are intended to understand a schedule rather than measure the quality of a schedule. 

On the other hand, there are metrics that do not have recommended thresholds even though there should have been one (e.g., number of concurrent tasks, number of redundant links, path convergence/divergence, number of constraints, average total float, etc.). ). Even if they have not been considered, these metrics may also be appropriate to measure the quality of a planning. 

METRIC ANALYSIS 

The selected metrics and recommended thresholds are detailed below. 

Nº  METRIC   REF. LITERATURE  DESCRIPTION  IDENTIFICATION AND CALCULATION 
1  Activity ID  4, 6, 8 y 9  Activities must have a unique identification number.  All activities must have a unique number 
2  Unique Activity Name  4, 6 y 7  All activities must have a unique name  All activities must have a unique number 
3  Activity Codes / WBS / Reference code  6 y 8  Each activity must have an activity code that includes 

a WBS by location, phase, etc. 

 A minimum percentage must be marked. Recommended >90%. 
4  Ratio of activities to milestones  4  Indicator of the level of detail of planning.  Divide the number of activities by the number of milestones. Not more than 10. 
5  Milestones without successor or predecessor  7  Each milestone should have at least one predecessor, one successor or both.  Percentage of milestones with no predecessor or successor. Greater than 95%. 
6  Milestones with resources  4, 7 y 8  Milestones should not have associated resources  None 
7  Milestones with duration  1, 4, 5, 7 y 8  Milestones should have no duration  None 
8  Start and end milestones  4, 7 y 8  Both must be present in the planning  Both present 
9  High duration  1, 4, 6, 7 y 8  Durations longer than 2 months (44 days) must be broken down (depending on the type of project).  Percentage no more than 5% (depending on the type of project) 
10  Severe Duration  6 y 7  Activities lasting more than 120 days  There should be none 
11  Project schedule / planning  4, 6, 7 y 8  There must be a particular calendar (or several) associated with the project including holidays and other exceptions.  Allocation of timetable(s) to all planning activities 
12  Predecessors and successors  1, 4, 6, 7, 8 y 9  All activities must have successors and predecessors.  Set percentage. At least 95 % of the activities must be fulfilled. 
13  Relationships end start  1, 4, 6, 7 y 8  Should be mainly relationship  Set percentage. Should be higher than 75%. 
14  Critical Path Test  1, 4, 6, 7, 8 y 9  By increasing the duration of the first critical activity in the programme, the end date should be shifted according to the increase.  Must always be correct 
15  Activities within the critical path  3  The number of activities should be adequate. Many activities denote simple planning.  Percentage of activities on critical path. Maximum 15 – 20 %. 
16  Relationships to hammock, level of effort or summary activities  4, 5, 6 y 7  There should be no such relationships with summary or hammock activities.  There should be none 
17  Constraints  1, 3, 4, 6, 7, 8, y 9  Strict restrictions (must start, must finish, finish at the latest, don’t start  No more than 5% of activities 
18  Resources  1, 4, 5, 6, 7, y 8  They must be associated to all activities with a duration of 2 months (44 days).  All activities 
19  High lags  1, 3, 4, 6, y 8  Gaps longer than 2 months (44 days) must be analysed (depending on the type of project).  No more than 5% of activities 
20  Severe lags  7  Gaps with duration longer than 120 days  There should be none 
21  Lags between activities  1, 3, 4, 6, y 8  Delays (lags) between activities must be limited. Long lags should be converted into activities.  Not more than 10% of the activities 
22  Negative Lags or Leads  1, 3, 4, 6 y 8  The following should not be used  There should be none 

Regardless of what is indicated in the table above, it is necessary to adapt the thresholds to the specifics of each type of project, with each organisation monitoring which limits are appropriate to ensure the quality of the formal structure of the planning. 

In any case, some of the metrics should be mandatory as they ensure correct planning structures, in order to be used later in follow-ups, sensitivity and risk analyses, cash-flow calculations, etc… 

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