Rules of Thumb

Pilots and other professionals verify that the work that they are about to undertake or work that they are engaged in has completed a series of checks. Simply following the checklists does not itself provide value, the value is insuring that the pilot and co-pilot take the time to consider all the variables facing them. The checklist is of no value without the context needed to interpret the items in the checklist. This is also the case with the rules-of-thumb listed below, each of these checks have caveats and must be considered in light of job- and client- specific requirements.

That being said, here is my pre-flight checklist for creating and using CPM schedules construction projects.

Activities to Include

The following checklist should be used to determine if you have defined the appropriate set of activities for your project:

  1. contract milestones must be included in the network.
     
  2. activities should be included for any required permits.
     
  3. activity classifications should include submittal, approval, procurement, delivery, installation, test, inspection, etc.
     
  4. submittal and procurement activities not specifically included in the progress schedule should be kept in another system which can automatically check approval and delivery dates with submittal activities.
     
  5. subcontractor submittal activities should be specifically identified.
     
  6. installation activities level of detail should reflect difference in trade productivity, e.g. studs, drywall, taping.
     
  7. installation activities level of detail should reflect differences in splitting activities due to weather sensitivity, e.g. drywall and taping.
     
  8. installation activities should be split into physical locations rather than percent completes, e.g. “1st Floor” and”2nd Floor” or “East Wing” and “West Wing”
     

Level of Detail

When determining the appropriate detail for activities the duration of the activity is the primary consideration. The following checklist will assist you to determine if you have appropriately defined activity' durations:

  1. if subcontract activities have longer than 20 day durations, that subcontractor must provide a fully integrated sub network.
     
  2. approval activities for contractor certified items will, generally, be two weeks in duration.
     
  3. approval activities for architect-engineer approval will, generally, be one month in duration.
     
  4. long duration procurement is appropriate for new technology or remote sites, however, all procurement activities over 100 days should be reviewed.
     
  5. installation activities should, generally, range between 5 and 25 days.

Activity Logic

The following checklist should be applied when developing or reviewing the sequence between activities:

  1. general activity template:
    1. submit
    2. approve
    3. procure
    4. deliver
    5. install
    6. test
  2. steel structure template:
    1. submit steel
    2. approve steel
    3. procure steel
    4. deliver steel
    5. erect steel
    6. install metal deck
    7. install deck slab
    8. fireproof steel
  3. cast-in-place structures template:
    1. submit concrete certification
    2. submit rebar certification
    3. submit concrete placement plan
    4. approve concrete submittal
    5. procure concrete materials
    6. deliver rebar delivery
    7. deliver concrete forms
    8. install concrete forms
    9. install rebar
    10. install concrete
    11. finish concrete
    12. cure concrete
    13. strip concrete forms
    14. move concrete forms
  4. pre-cast structure template:
    1. submit pre-cast drawings
    2. approve pre-cast drawings
    3. fabrication pre-cast
    4. deliver pre-cast
    5. deliver crane
    6. install pre-cast panels
    7. install pre-cast tie strips
    8. install caulking
    9. seal pre-cast
  5. partitions template:
    1. submit drywall partition system
    2. approve drywall system
    3. procure drywall system
    4. deliver drywall system
    5. install metal studs
    6. rough plumbing
    7. rough electrical
    8. rough communications
    9. install drywall
    10. tape and finish drywall
  6. mechanical rooms should be scheduled as early as possible to give access to the installation crews.
     
  7. exterior closure should incorporate separate activities for building "skin" and window installation.
     
  8. in some cases sealing and caulking the exterior after window installation should be included.
     
  9. in high- and mid-rise buildings the building skin of the 1st and 2nd floors should, generally, be scheduled last.
     
  10. in high- and mid-rise buildings installation activities should, generally, be the same on every floor.

Critical Path

The following items should be addressed when reviewing a schedule's critical path:

  1. all activities which have a float of one working week or less should be considered critical activities.
     
  2. if more than three parallel critical paths exist, it is likely that some durations have been overstated.
     
  3. the ratio of critical to total activities should be reasonable. A high ratio of critical to total activities suggest that float has been manipulated, a low ratio of critical to total activities suggests that there is to little detail on critical path activities.

Large Float Ranges

Once the schedule has been calculated, run the total float report. When evaluating the ranges of float in a schedule the following items should be addressed:

  1. a. All activities with over 100 days float should be investigated.
     
  2. b. Installation activities with over 100 days float are not integrated into the schedule properly.

“Cost Loaded” Schedules

When evaluating the anticipated earned values added to activities the following items should be evaluated:

  1. no cost will be allowed on submittal, or approval activities.
     
  2. the cost of all activities may not exceed the contract amount
     
  3. activity costs should range is between 0.1 and 2.5 percent of the total contract amount.
     
  4. unit prices and quantities of early activities should be the same as the prices and quantities of the same type of activity which occurs later in the project and activities which have larger quantities.
     
  5. the ratio of (critical path cost) to (total project cost) should falls within an appropriate range.
     
  6. projects should not be front end loaded: (a) At 1/3 complete in time the contractor should have received 114 of the contract amount, (b) At 2/3 complete in time the contractor should have received 3/4 of the contract amount.
     
  7. delivery of electrical and mechanical activities may distort front end analysis and should be reviewed.

last updated 05 Sep 2010