Productivity of Equipment and Manpower

Ammar,

Sometimes you can schedule an activity with several different crews.

Say you have a 200cm/hr excavator and a 400cm/hr excavator but there is only room for one such piece of equipment per activity/location. Depending on availability of the excavator it might be the most productive is available but at times activities will be competing for the excavators and best assignment will depend on selection that will result in shorter overall project duration. This can be automated within Spider but in P6 it might be impossible so you must be constantly alert to see if initial assigment is still the better choice.

The following figure is from a sample schedule that illustrates this kind of scenario. Activity 002 can be assigned either the 200 cm/hr excavator crew or the 400 cm/hr excavator crew. Activity 002 was expanded to show the 400 cm/hr excavator crew was selected for this particular activity while the histogram shows the 200 cm/hr excavator was assigned at the same time to one of the collapsed activities.

Scheduling is not merely about making it feasible but about making it efficient. A good PM is always looking for methods improvements and adapts the schedule to changing conditions. If your software is of not much help on the issue then get used to analyze the options using manual what-if scenarios. 

Best Regards,

Rafael

Vladimir,

Your example is perfectly simple. If you are using variable resource quantities I doubt this functionality is available in P6 and partial workloads won't be enough to create a good model with P6. In this case efficient use of one excavator shall be intermittent [interrupted] also other interesting cases occur when resource availability can make more efficient use of equipment by activity splitting. 

Ammar,

Be aware that the common practice of assigning equipment to WBS activities can yield unrealistic schedules. If you assign a crane to a summary activity or a WBS the resource might be overloaded. 

Say you assign a single crane to Concrete Structures WBS, that you have four structures that can happen at the same time. In this scenario it might be that several activities within each structure require the single crane at the same time, too many activities for the single crane to handle. At other times no activities might require the crane during some time periods.

This approach will not tell you when the crane is used, by how many activities, if overloaded or if partially or completely idle during all periods.

We assign the crane to each activity using partial workloads in this way if the crane is required one hour on 20 activities the software will know it is overloaded and the resource leveling will assign the crane to a maximum of 8 activities per day if 8 hours per day calendar. Obviously it is most common some activities will require the crane a few minutes while others a few hours or even the whole day. 

In this way we can get correct resource leveling and can make our reports for crane usage and crane idle time.

Perhaps this idea on assigning equipment to hammocks/level of effort/WBS comes from the old software of the 70s with very limited capabilities, very frequently it was wrong but the software at the time offered on real options. Although Spider has a richer set of functionalities for resource planning I believe there is a way in P6 to model partial assignments. I believe on resource tab if you display field for hours/day you will find by default it might be 8h/d but it can be changed. 

There are no fixed rules and no perfect schedule, so never say never, at times a compromise is in order. Say you have assigned a single pick-up truck to be used as needed for any activity. It would be unpractical to assign it on partial assignments to all activities. 

Best Regards,

Rafael

Rafael,

this case is even more interesting:

Ammar,

P6 does not have productivity field. Duration shall be adjusted manually.

Regards,

Vladimir

Hi Ammar

The way i plan and schedule and make sure that resources are used effectively is as follows.

• For long term static utilization of equipment i assign these to a WBS summary. Cranes etc.
• For specific resources i create an resource in the enterprise tab and note the quantity and the time they are available. Then assign the required resources to the respective activities. When this is done you view in the resource tab whether the resource is sufficiently available. The next step is to determine the number of resources that can effectively work together. Update the duration of the activities to match the most effective performance.
• The next step is to level the resources,if the resource requirements are overloaded during a specific time period. This can be done manually or automatic in P6.
• Manually leveling can be done by making relationships between the activities with the specific resources and this will give cascading activities.   
• Automatic leveling in P6  possible. Go to the leveling  tab and create the leveling options. Start with one resource at the same time and use the leveling priority and for starters only leveling in the free float. 

Regards Johannes

PS. I have some example on my website. www.plannenvoornietplanner.net

Hi Ammar

Sorry i missed your point. I have not done this on P6 the way you describe.

Regards Johannes 

Sometimes optimization of some individual part does not yields global optimal.

It is not difficult to imagine a scenario where longer duration of Activity 1 can yield shorter overall duration if it releases some resource that can be simultaneously used on a critical activity. The overlapping of activities will reduce overall project duration. 

In the following figure you will see that the scenario that yields overall shorter duration of 3.00 days is the one with a duration for Activity 1 of 3.00 instead of the schedule where Activity 1 duration is 2.50 days.

Both schedules are based on the productivity of the excavators determining activity duration. Note that the volume of work for each activity is also the same on both scenarios. Also note how partial workloads allows you to assign one of the excavators to work on two activities the same day while the other works full day on a single activity. 

The scenarios are so simple that if your software is not capable of mimicking the model you can verify the allocation manually.

Hi Ammar

I would consider the following. How many excavators can work at the same time and still be productive? Say ,you can work with 2 excavators, then the duration is 2.5 days. So why should you take a 3 days duration while it can be done in 2.5 days. They can be assigned to another task for the remainder of the day. Activity duration shall be as short duration as possible.

Regards

Johannes

How best to tackle the issue depends on the software, some will substantially help others will require full manual adjustments without any assistance of the software. The following figures are from Spider Project with can tackle the issue in a very transparent way that is easy to follow.

In any case if using 1 excavator at the specified production rate it will take five days.

If using two excavators on full assignment workload it will take 2.5 days.

In order to balance the assignments to 3 days then one of the many alternatives would be to assign the 2nd excavator to work on the activity 66.67% of the day.

Good resource planning software shall not only assist in determining activity durations with specific resource loading but shall be responsive to more complex scenarios such as adjusting activity duration depending on resource availability otherwise you will be at the mercy of having to adjust manually your resource assignment on every update if you want to improve the schedule. 

If you are using Spider Project then we can go to more complex scenarios as this one is too easy. If using other software it will be interesting to see how it is done.