Part 2 of a 4 Part Series on Incorporating Weather Days into Your Project’s CPM Schedule
By Mark Nagata & Bill Haydt
This article was first published on Trauner Ideas & Insights and is republished here with permission. Copyright © 2018 Trauner Consulting Services, Inc. All rights reserved.
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 calendar that best represents when that particular work activity will be performed.
One way to account for adverse weather is to identify days that would otherwise have been workdays as non-work days in the work calendars.
The advantage of this approach is that the contractor can show that it separately accounted for anticipated adverse weather in its project schedule by simply referencing the calendars that have adverse weather workdays built into them. It also provides a somewhat realistic depiction of when the project might incur adverse weather conditions and, thus, may more accurately forecast the dates that work will actually be performed on longer projects.
For example, let’s say the contract states that the contractor should plan to lose 4 workdays to adverse weather in the month of June. The default 5-day workweek calendar for June includes no holidays and, therefore, every weekday is an available workday (see Figure 1, below).
In this scenario, to accommodate the contract’s requirement to assume 4 workdays lost to adverse weather in June, this calendar could be modified to block out 4 workdays as non-workdays. In Figure 2, below, 4 of the Fridays in June have been identified as non-workdays.
Another option is to create project or activity-specific work calendars for operations that are subject to additional working restrictions. An example of a project-specific calendar is a weather-sensitive or winter work calendar for activities that are subject to seasonal or winter work limitations. In these work calendars, all of the workdays in the winter months are identified as non-workdays in the work calendar.
For example, let’s say that there is hot mix asphalt (HMA) paving work required on a highway project, and the contract requires that “no base paving (HMA) placement will occur between November 15 and April 1 without the written permission of the Engineer.” In this scenario, a work calendar could be created that specifically includes these work restrictions by marking all workdays during that time period as “non-work” (see Figure 3, below).
The primary criticism of blocking out non-workdays in advance for adverse weather is that no one can predict when it will rain or snow in the future, and when work won’t be able to occur. For example, some work that usually cannot occur during the winter can and is performed, particularly if the winter is unusually mild. However, by including the anticipated non-workdays due to adverse weather in work calendars, it is possible to ensure that the contractor’s plan, as depicted in the project schedule, provides a realistic forecast of when future work is planned to occur by accounting for workdays that might be lost to adverse weather in the project schedule.
Note that the success of this approach depends on the how carefully and honestly the contractor puts the schedule together. For example, many times the owner does not identify the number of days that the contractor should plan to lose to adverse weather. Even if the contract does provide a number, the contractor may not be obligated by contract to incorporate these days into its work calendar. Lastly, contractors may address weather delays differently than the schedule assumes. For example, if the contractor plans to work Saturdays or overtime to overcome weather-related delays, then some owners might take the position that a certain number of Saturdays should be added workdays – in addition to blocking out workdays for adverse weather.
Bill Haydt and Mark Nagata are Director, Shareholders of TRAUNER. Their expertise lies in the areas of construction claims preparation and evaluation, development and review of critical path method (CPM) schedules, delay analysis, training, and dispute resolution. They direct and perform all types of analyses from schedule delay analyses to inefficiency analyses and the calculation of damages.
Bill can be reached at bill.haydt@traunerconsulting.com
Mark can be reached at mark.nagata@traunerconsulting.com
More in the next blog post, Part 3 of a 4 Part Series on Incorporating Weather Days into Your Project’s CPM Schedule…
(Source: Nagata, Mark, and Bill Haydt. “Incorporating Weather Days into Your Project’s CPM Schedule.” Trauner Consulting Services, Inc., www.traunerconsulting.com/incorporating-weather-days-into-your-projects-cpm-schedule/)
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