The Lookahead Schedule and 90/60/30

Sep 5, 2019 | News, scheduling

Executive Summary.  Once the project starts, it is the Contractor’s project management team’s responsibility to update the client on a regular, usually weekly, basis.  This is done graphically using a lookahead schedule in bar chart format (also known as a Gantt Chart).  Here we discuss the contents and reliability of the lookahead schedule.

What’s a project schedule versus a lookahead schedule?  At the beginning of a project, the Contractor is usually responsible for submitting a schedule which shows the critical path of the project.  The owner then uses this document to track the progress of the Contractor, and to contribute in the determination of merit in a delay claim.  This project schedule is at a much higher level (less detail) than the lookahead schedule.  It is made prior to the project start date.

The lookahead schedule is usually generated on a weekly basis and is much more detailed than the project schedule.  It usually looks at the current week of work and then the next two to three weeks, beyond the current week.  A lookahead schedule shows the following types of activities, which often times are not seen in a project schedule:

  • Discrete work items separated on a crew-by-crew basis
  • Concrete pours by number and/or bounded by structure grid lines
  • Steps within a process (for example “setting a manhole” on the project schedule may have “set the base”, “set the risers and top”, and “grout the joints” on a lookahead schedule)
  • Material deliveries
  • Subcontractor details (for example “street lights” on the project schedule may be replaced by specific light pole-to-light pole segments)
  • Testing
  • Special inspections
  • Meetings
  • Road closures
  • Night work versus day work
  • Holidays/non-workdays

A lookahead schedule is a useful tool for both the contractor and the construction manager in leveling manpower.  A contractor can track his/her crews each day of the week and the construction manager or owner can plan his or her own inspection services.

Reliability of the schedule.  The project schedule is a macro tool for ensuring that, within a reasonable level of certainty, the project will finish on time.  The project schedule is reliable for ensuring timely project completion; however, what happens on a week-to-week or month-to-month basis is likely not as predictable on day one of a project.

Interesting though with the lookahead schedule, even though living in the present and having the benefit of real time events, perhaps the lookahead is equally as unreliable!  This sounds like it makes no sense as the project schedule may have looked at an entire year of work when the lookahead is looking into the future only three weeks!

The 90/60/30 rule.  It goes like this from the presenter when the lookahead is handed out at the progress meeting:  “I’m pretty certain that this week’s schedule is correct, but the next week I think I’m about 90% accurate, the following week I’m only 60% sure of the activities, and the third week there’s about a 30% accuracy ‘guaranteed’”.

My story.  I stole this article subject from a buddy of mine – this whole 90/60/30 rule.  But I’ve done a thousand of these schedules and he’s right, the schedule is as reliable as the weatherman.  However, one thing that can be very helpful in the management of a construction project, or a post-mortem, is the week-over-week comparison of the Contractor’s performance.  What the Contractor is preparing for and what actually happened may become critical in a negotiation between Contractor and Owner.  All the superintendent or project manager can do in the preparation of the lookahead is to prepare a schedule based on what (s)he sees today.  The success of a project is achieved in the adjustments to the hourly and daily site changes which ultimately make any lookahead schedule obsolete anywhere between five minutes before, to five days after your presentation to the owner!

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