Vertical Traceability
Vertical traceability demonstrates the consistency of dates, status, and scope requirements between different levels of a schedule—summary, intermediate, and detailed. When schedules are vertically traceable, lower-level schedules are clearly consistent with upper-level schedule milestones, allowing for total schedule integrity and enabling different teams to work to the same schedule expectations. In this way, management can base informed decisions on forecasted dates that are reliably predicted in detailed schedules through network logic and actual progress.
In addition, vertical traceability allows managers to understand the effect on key program and G/R milestones if their lower-level activities are delayed. An activity owner should be able to trace activities to higher-level milestones within intermediate and summary schedules. Even though their activities may be rolled into a higher-level milestone, responsible owners should be able to identify when and how their product affects the program.
All levels of schedule data, from detailed through summary schedules, should be derived from the same IMS. Ideally, the same schedule serves as the summary, intermediate, and detailed schedule by simply creating a summary view filtered on summary activities or higher-level WBS milestones. Summary schedules created by rolling up the dates and durations of lower-level elements are inherently vertically integrated.
Often the program schedule is represented by presentation software in a completely different format. If alternative presentations represent the program schedule, the program management office should be able to demonstrate that they are consistent with the schedule.
It is important to note that vertical traceability is not simply the ability to collapse WBS elements within the same contractor schedule. Vertical traceability implies the ability of the contractor schedule to roll up into the overall program schedule, which includes government activities, other contractor schedules, and interfaces with external parties, even if constructed in a separate computer file or different software package. All the program’s project schedule information, from the suppliers through the contractors and government agencies, should be collapsible into one overall IMS.
Finally, vertical traceability applies to all schedule data that are reported to and by program management. That is, schedule information such as forecasted dates, predecessor logic, and critical path activities reported to management should be rooted in and traceable to the actual program IMS. Case study 10 gives an example of the absence of vertical traceability between schedules.
For this study, GAO reviewed the most current schedule and cost estimates that supported DOD’s February 2012 Milestone B decision, which determined that investment in the Air Force Defense Enterprise Accounting and Management System was justified. Our analysis did not find vertical traceability within the schedule for Releases 1 and 2 of Increment 1—the ability to consistently trace work breakdown structure activities between detailed, intermediate, and master schedules.
For example, we traced three activities between the government schedule and the underlying prime contractor schedule, and in each case we found mismatching start dates that differed by a day, a week, and a month. Vertical traceability ensures that representations of the schedule to different audiences are consistent and accurate. Unless the schedule is vertically traceable, lower-level schedules will not be consistent with upper-level schedule milestones, affecting the integrity of the entire schedule and the ability of different teams to work to the same schedule expectations.