Arun,

Be patient, the discussions has not even started yet, it is just a warm-up.

Mike has an interesting point and I just want to add a situation that maybe hasn’t happened yet but there maybe some possibilities, like for example:

If you are going to enter into a bidding for a contract that would not be measured against prices, but in terms of time, like which Contractor can deliver in the earliest possible time (regardless of the price)?

Anoon

I would say a contract time is reasonable when it can be achieved under the contract terms without unusual effort, with smooth resource usage.

Usually initial contract durations are given by the designer based on prior experience on similar works. Because every job is unique this is not a universal number.

Through experience you learn a few ways of estimating job durations, for example for a ten stories condo you might estimate 10 weeks for earthwork and foundations, 2 weeks concrete-work/floor or 20 weeks (can be faster depending on particular design), 2 weeks to include roof parapets and machine room concretes and 16 weeks to finish after concrete-work is finished as architectural finishes overlaps concrete-works, plus 6 weeks for final punch list and delivery. As you can see this is a conceptual way of estimating duration. It can also be using a conceptual CPM, a CPM not as detailed but good enough to give you an idea.

For complex industrial jobs a detailed CPM from a consultant would be in order.

About liquidated damages it should be close to the cost per day the Owner loses for not having available the facility on time. This represents loss of business, construction financing and any other cost. If for some reason this is not enough the Owner still have the right to claim for extra cost, although the idea is that this settles the issue. I have never been involved in a case where the Owner claim for extra cost but understanf in legal theory it might happen.

My experience has been that liquidated damages tend to be reasonable; the issue is more with the reasonability on duration. It is not uncommon for conceptual duration estimates to miss particular difficulties that limit the sequence of works.

Best regards,
Rafael

Anoon,

If the contract time is reasonable you should be able to schedule your job using standard crews that will yield efficient use of resources and therefore lower cost.

On the other hand if allowed time is not enough you will have to deal with the issue by comparing your options, one is use of larger but less efficient crews, use more formwork at the cost of less re-use, more crews, use of shifts and so. At home at times when the duration is kind of impossible or the use of other methods is more expensive than liquidated damages, we estimate an allowance for liquidated damages and oops! finish 20 to 30 days late, blame the Owner for delays and most of the time end up not paying liquidated damages at all.

About recommending software, it got to be your choice, but if you are serious about resource loading your job, and better be as no job is done without resources, select one that gives you true float under resource leveling otherwise your Project Manager when looks at the available float will be misled and most probably make the wrong schedule adjustments.

It is unbelievable how many software, over 90% of the options, misled the contractor under resource leveling and they, the client, don’t even know it, or don’t complain or even sue the software vendor or CPM consultant for damages by knowingly misleding the client about float. Remember software companies have no professional liability as a designer or doctors have, they are not bound by the same standards, a disclaimer note is enough to allow them for any low performance without resposibility, for most it is just about making money, looks and marketing takes precedence over substance.

If you want to talk about my software of choice capable of providing true float we will have to do so under “Lets Challenge Spider” that has become kind of a monstrous thread where topics are at random and there is no way you can go back without reading such monstrous thread every time you are interested in a particular topic. Yes kind of useless but these are the rules we are bound to obey as per moderator’s instructions.

Best regards,
Rafael

Anoon,

Man-days are related to hours per day, you got to define your relationship. It is kind of a standard relationship to mean one man-day = 8 man-hours, of course you can re-define it, you are correct. It might be that work on an offshore rig is based on longer hour shifts as to optimize living headquarters capacity.

If you have different duration shifts or might this happen you will be better off by using man-hour as your unit of labor work.

About letting your software drive activity duration based on availability of resources you got to be careful.

Work requiring 2 men for 5 days does not means 1 man will take 10 days, probable no work can be performed if working alone; it will take forever for a single man.

I prefer to use crews for our type of work, the production of the crew defined as a group as adding more men to the crew does not necessarily will increase production. Even tools and equipments are tied to crew production for most construction work activities. Because there are economies of scale as well as diseconomies of scale, a crew usually has an optimal size, this is the one you target under normal conditions.

On the other hand there are activities that do not require work to be performed by a crew working together; this can be the case of design work and software development.

Because this is not necessarily true for all industries or for all activities within a single industry the software provides you with the tools that allow you to select the option that best models your needs.

Best regards,
Rafael

Mike,

Arun in his initial posting made reference to the issue on shifts, quote "In my site it is a 10 + 10 two shift for the structural team and 10 hrs 1 shift for the finishing team ??"

His question about man-hours and shifts go to the bare bone of scheduling. He made it clear he understand what man-hours is, he made it clear he was looking for other point of views regarding the scheduling of man-hours and modeling of shifts.

If we are interested on the issue of modeling shifts as it relates to man-hours shall we also move to "Lets challenge Spider"? Then, why not moving all threads into "Lets Challenge Spider".

His question on “How it is calculating?? I understood it as how the scheduling software distributes man-hours allocation and calculates cost from it. Because like you, at home we are required to keep our schedule balanced with the assigned budget some question came from my part as how to model my need to assign “extra” personnel with the knowledge they will not be available all time, that I need to model the assignment of 13 men as on average I will get 12 men every day at the jobsite, on average one will always be absent or be assigned temporarily to other activities.

This is a scheduling and planning forum; in these days no serious job is done without the use of computer software, there is no way you can discuss these themes without getting into the functionalities of available software.

A few days ago I received an e-mail from PP regarding the possibility of organizing the forum by industry. What if someone else is discussing functionality under an industry different from mine, in such case will I be able to move the thread into my industry specific area or shall I create a parallel thread under my industry? No matter how you organize the forum some overlapping will always occur.

What about the inability of most software to show correct float under resource leveling, incapable of showing true float even under a 2 activities resource leveled schedule. Most software for decades have been misleading people into believing available float as shown in their output is always correct. It is such an abominable error it should be reminded constantly; otherwise we would be promoting lies. Is this also to be required to be kept under a single topic? Probably a permanent listing of all possible topics must follow so we keep our discussion on a single specific topic as defined by PP admin.

Maybe your insistence on banning lag should be kept under a single permanent forum thread, say under "Let’s Challenge Mike". I don’t really believe you should be silenced, although I do not agree with you in this issue you are not alone and your insistence on the traps on this issue is valid, it is good someone remind us of this.

Best regards,
Rafael

Hi Rafael Hi Vladimir

This inocent thread has been hijacked and turned into another "Lets challenge Spider".

Please stop it.

I have asked admin to set up a dedicated forum for you two to chat to each other undisturbed by moderators and anyone else for that matter.

Best regards

Mike Testro

PS - you could always ask to be moderators.

Rafael,
you can create hammock activity Idle Hours and assign there your resources whose idle hours will be paid using special rates. This activity shall start from the moment when resources start to be used and to the end of their usage.

These assignments shall be with Variable Quantity and Workload. Minimals shall be set Zero. Set this in the assignment Properties.

If resources are paid for work hours and their rates were defined in resource table then add assignment cost per hour at this assignment that may be negative.

Resources will be assigned to this hammock activity when they are idle.

If machines are paid for hours (not for work) their costs shall be assigned to hammocks that last from the first to the last use of the machine.

You will like variable assignments. For an example you can define that some activity can start if 6 workers are available (minimal quantity) and others may join when become available until the total number of assigned workers will become 12 (maximal quantity).

And vice versa - if 12 workers perform the work and other activity with higher priority require workers, 6 of them may be moved there and return after the job will be finished.

Very useful in practical scheduling.

Best Regards,
Vladimir

13 workers will do the work faster that 12 and you will pay for less hours. With 92% workload they will do the work for the same time but everybody will work 92% of activity duration and again will be paid less if they will be paid for hours of work.
You can select to pay for the calendar hours if it is the rule.
Best Regards,
Vladimir

Rafael,
here the pre-contract estimates are usually based on the common construction norms. I think that Means database can be considered as the analogue.

But each company has its own specifics that may differ from what was considered in these common norms (specific equipment, machines, personnel with certain qualification, etc.). The crew that is used on the certain work can be different if to compare with Means proposals, sometimes the technology may be different too.

The schedule based on the common databases may be established as the contract schedule (and cost). Doing the work construction manager may want to accelerate some works, to assign additional or different resources (excavator that is not quite the same as the example). And managing the construction the Contractor wants to get some profit - it means to perform the work cheaper than in the baseline.

In any case it is not obvious that the Contractor at any moment will have all resources that are necessary by estimates available, and if, vice versa, there are more workers than necessary by estimates some of them will go home instead of doing some useful job joining the crews.

Here resources are assigned by site managers basing on the schedule and availability. It would be considered as nonsense if the work with estimated amount of workers 12 will not start if we have only 10 workers available, and if we will sent 2 workers home if there are 14 of them. And it is usual to pay for the amount of work (volumes), not for the hours. Idle hours are paid for the special rate.

Best Regards,
Vladimir

Hi Vladimir

I am looking at it from the Contractor’s veiwpoint where the estimator set out the production rates before the job starts.

The project manager should use these estimated production rates in his resource modelling as this is the only way to establish the inegrity of the "Time - Cost - Scope" triangle during construction.

Best regards

Mike Testro.

Hi Anoon Hi Vladimir

The person who assessed the productivity of all aspects of the project is the estimator who won the job.

There is no point in trying to establish different production rates in the programme.

The estimate should be broken down into Labour - plant - materials - O’heads etc.

It is the labour and plant sections that should be used to drive task durations.

If the estimator has got it wrong then the problem will soon be disclosed and he will benfit from the feed back.

Best regards

Mike Testro

Hi Amom,
resource assignment productivity depends on the type of activity where this resource is assigned.
Doing something manually or with the help of some machine are different activity types. So assigned crews are different and productivities are different.
Different projects usually consist of different sets of activities, but resource assignment productivities on the same activity types are the same.
Best Regards,
Vladimir

Hi Vladimir

The discussion is about Man Hours / Man days but you are right that in some tasks machine hours are predominant.

In this case the productivity of the "lead" machine drives the duration.

As you well know the output of the excavator has to be balanced by the number of haul units that are assigned to it and if there are not enough haul units for the turn round distance then the excavator will be working below peak capacity.

Best regards

Mike Testro

Hi Anoon

You are quite right regarding the definition of resource allocation.

With my simple method productivity rates are not required - just the number of Man-Hours balanced by the gang size.

Best regards

Mike Testro

Hi Anoon

The term "Hours" is a convenient way of describing the resource work load of 1 operative in 1 hour - "man hour" if you like.

The hours can be rounded up to the number of hours in a work day - it would then be a "man day"

Man days would be levelled in the usual way by setting a limit on deployment and letting the software do it for you - although I prefer to do it myself manually if there is more than 1 resource to be levelled.

If you have key resources then they can be allocated to the relevant tasks alongside "hours" but not resource modelled - they can then be levelled independantly but within the max "hours" over ride.

This is anothder benefit from a bottom up plan - only 1 resource per task gives better levelling results.

Best regards

Mike Testro

Hi Anoon

I have described my very simple method of resource modelling before in this forum.

1. I have only 1 resource called hours.

2. Hours are extracted from the cost plan by way of extracting the labour value and then dividing by the local hourly rate.

3. Hours are then allocated to the respective tasks on a pro-rata basis.

4. The task duration is then generated by a suitale gang size.

This method has a number of beneficial side effects including.

1. The extra time generated by increased quantities is automatic.

2. Regular progress reports will also feed back to the cost valuation.

3. There is a direct link between scope of works and time.

4. There is no requirement for lots of labour outputs.

And it takes about 4 hrs to fully resource up a big programme.

FARTFM = Find and read the fascinating manual.

Best regards

Mike Testro

this applies to 1 person/worker per day for each activity, right?

Hi Mr Arun ,
Let us take rebar installation ,
Act 100 has 10 days - 10 hrs working = 100 hrs
Act 200 has 20 days - 8 hrs works = 160 hrs
Total hrs = 260 hrs

If you consider 10 hrs is equal to 1 day then rebar installation is 26 man days .

Regards ,
TN Shanmuga

Hi Arun

In my case it is usually FARTRTFM.

Best regards

Mike Testro

Read The ******* Manual

Hi Arun,

Sorry, just give way to elders, someday you’ll be in the same situation (hopefully).

Going back to "Man-days", this may sound basic, but I believe not everybody really understands this (including me). What if you say "Crew-Days"?

When making a schedule, you simply guesstimate the "Duration" and this is usually in man-days (even without knowing it). Say you put 6 Days duration for an activity, even without having any idea on what resource(s) to be assigned.

Further, I supposed that not All really think of Crew(s), the first time they draft a schedule.

By the way, Mike, what do you mean by RTFM?

cheers

Hi Arun

A very simple reply.

You have been planning for 10.5 years and you still do not know about basic resource modelling?

What have you been doing in all that time to develope your planning expertise.

The best thing you can do is RTFM.

Best regards

Mike Testro