Construction management Parte A + B - Voto 30

Construction management: Rigamonti

18th September 2020

Construction market is the space where offers match demands, where we find different requested: technologies, services, with quality, with safety.

Project and investment

• Define targets, the main goals, they have to be well defined for everyone, first thing that the project manager has to do;
• Define of phases, that will drive us to achieve targets;
• Scheduling: time and economic budget which are defined by resources.

Finally the project start.

Execution, which belongs not only to the control of construction site. To every activity we have to apply control and management. It’s also known as performance analysis.

Three main level

• Construction management: It starts when the operative design phase is finished so when the work starts.
• Project management: In public Italian committent there’s the RUP.
• Product management: It looks to building as something that have a life cycle, this is the complete way through which look to building in 2000s, the new figure that conduct this level is a product manager who looks at the building as a product, so it has a lifecycle, a duration.

This phase start with feasibility study, which give us the concept of the building. We have to look to the building from all the perspective and also consider the evolution of building status in its life cycle. When we chose a technology it will determine the maintenance and so the cost and the life cycle.

Project management - different approaches

• Function approach, old way to organize.

Functional organizational chart where each people organize work everyday to do the best in an office, in a functional view: each one look to the function and try to its best.

With this approach it’s impossible to apply project management technique because in this one people try to do their best only in their field.

This was correct when the market was asking always the same building, with the same plants, windows. When there were not so many variables, only the dimension, quantity variable.

• Projects approach.

We don’t have function, we have project. We all to look to all the aspects which are linked together, so we organize different rooms where we link together different people who conduct a project, they report to the direction of the company in a project and functional mood.

There’s a leader who have to report/refer to the Director of the company who the project is going on from a 360 perspective.

In this model we have to manage people.

Flexible project flexible organization, not only one-dimension goal but a multidimensional goal: time, cost and quality, which must the reached together.

The previous approach to organize people was functional approach: where every worker tries to do the best in its particular skill. In projects approach the main goal is not doing well the specific work but to reach the goal of the whole project, there are more targets than the only one of “doing our job in the best way”.

Project management

Set of human and material resources combined in a temporary organization to achieve the defined targets of time, costs and quality, with limited available resources. With limited available resources we have to optimized.

Without resources we don’t do nothing, this is the reason why they are so important, could be:

• Internal,
• External.

NB: time, cost and quality must be managed together!

WBS index of the project, of the execution.

The last level is the one of activities, for each activity we have to give time and resources!

It’s not only a tool for the initial estimation but also for control during the execution of a project.

It grows in levels with the growing of design, the design became more and more details, WBS starts to have more and more level.

NB: not all the activities must have the same number of levels.

A good estimator doesn’t go too deep, but he focuses on the most important things. We have to estimate initially not only the resources which request a big amount of money, but also the resources which needed a long time to be delivered to the building site.

25th September 2020

Estimation phase

It’s not only cost but also time, in this phase are evaluate the main time of the process.

Work planning

WBS: the useful technique.

Planning is divided in a vertical way the work, starting from the upper level, project, and go down until the last level of activities.

Scheduling is put the planning, a vertical breakdown, in horizontal: so in time.

Bill of quantities

For each activity, or work package, of WBS.

It gives me the exact number of sqm that I have to realize in a project.

Total Resources Calculation: BoQ x RA = TRC.

Don’t answer only to cost question but also to time question, from it we can also found info about duration.

Resource analysis

Resource I need for one quantity unit.

Cost breakdown structure

Breakdown structure of cost.

We start from the bottom of the breakdown, the simpler type of cost, and we go up until the total cost and finally, adding markup and risk, we are able to obtain the price.

• Direct costs: costs that can be directly assigned to a specific activity, so there’s a univocal link/assignment between resource and activity.

Ex: labor, materials, machines, subcontractors that are univocally used for a particular activity, 1 resource 1 activity.

In a project the main costs are direct.

• Operational indirect costs: cannot be assigned to only one specific activity but direct on building site.

They are about 10 - 12% of direct costs.

They became higher if match with direct cost. In maintenance site the percentage of indirect costs with respect to direct costs is higher.

Ex: building site installations, building site management, approval activities.

Direct costs + operational indirect costs = operational costs.

• Legal/financial indirect costs: costs that cannot be assigned to only one specific activity, they are directly linked to the contract agreement.

Their origin is due to contract requirements, law requirements, financial tools.

They are about 2 - 3% of direct costs.

Ex: insurance, deposits, bank guarantees, financial burden, cost for bid administration office manages this kind of costs, so it’s very important to identify and isolate them.

Example: indirect cost splitting

Operational costs + legal/financial costs = constructions budget.

Op. indirect costs Hp: This machine is only used by activity “Esecuzione 1) Disk saw (SC1) rivestimento esterno mattone faccia a vista” (AT.01.01).

In this case the indirect cost SC1 is equal to a direct cost and it’s totally assigned to activity code AT.01.01.

NB: It’s important to define clear criteria to split.

2) Mixer (BET1) Hp: This machine is used by all the activities belonging to the working phase “Murature” (AT.01).

Indirect costs on the construction activities. The indirect cost BET1 is split according to specific criteria among all the activities included in the group AT.01.

Indirect cost splitting of indirect mortar quantity used x by specific activity cost «BET1» total mortar quantity.

• General costs, or external.

Not strictly linked to building site or contract, but they are linked to the company activity as strategies.

They are about 6 - 8% of direct costs. The lower is these amount the higher is the quality of the company, because this means that the company is able to complete a project having a lower amount general cost.

Ex: employees expenses, office expenses, warehouse management costs.

Direct costs + indirect costs + % general costs = total costs.

NB: a % of total costs foreseen to prevent costs due to uncertainty of some analysis, it’s important to consider also accidents, this one is managed only by the directors of the company.

• Risk.

It’s different from accident, it’s uncertainty of design, while risk is independent from design, each hazard that could impact on the project causing financial damages.

It can deal also with economic, society, … risks.

Risk is a % of price kept as financial reserve to cover some economic issues.

Total cost.

Total costs + margin + risks = price.

• Margin.

Profit expected by the company for the project.

NB: taxes are not cost, they are part of margin. Cost breakdown structure NB: Indirect costs are strictly related to time more time: higher indirect costs.

Price legal/financial tot M R Costs that cannot be asqpCg Cdir.+ Cind. but that are directly linTheir origin is due to cCop. Cind.lf. requirements, financial Es: Insurance, Deposit Cdir Cind.op. burden, Costs for bid,

Op. costs + leg./fin. ind. costs = const!!

Remark: It’s important to define a clear criteria to split the construction activities.

2nd October 2020

Machine and equipment management

Rental cost

• Ownership cost: deprecation, extraordinary maintenance, taxes, insurances.
• Operational cost:
• Installation: as freight, installation or disassembly It’s an indirect cost, for example for tower crane, we install and disassembly it just one time in our construction site, but we use the tower crane for a lot of activities.
• Usage: everyday cost, such as energy, labor, ordinary maintenance It’s a direct cost, which can be associated to the single activity.

Tower crane now 1y 2y.

Buy 100.000,00 € 100 100,02 100,04.

Life cycle (years) 10,00 years.

Sell at the end of life cycle 20.000,00 €.

ir 2,00% (1+ir)^years.

Sell at the end of life cycle, considering ir 16.406,97 €.

Depreciation.

D = (purchase amount - sales amount at the end of life cycle) / life cycle.

Annual cost that all my construction site have to pay to the general management of the company for the usage of the tower crane.

8.000,00 € per year.

Depreciation without ir 666,67 € per month.

8.359,30 € per year.

Depreciation taking into consideration ir 696,61 € per month.

Critical resource: the resource whose duration can affect the duration of the whole project.

For example, concrete pump duration isn’t critical while the labor of an activity is considered critical because it determines the whole duration of the project! This is why for an activity we can put two crews instead of just one, in this way the “labor” is less critical for the duration acceleration of activity.

Bill of quantity total resources

id descrizione um Q id descrizione um Q.

1 Operaio Skilled labour specializzato h 1230.

E.1 External brick veneer mq 2050 2 Semiskilled labour h 1230.

3 Unskilled labour h 1230.

4 Bricks 12x25x5,5 p 100450.

Resource analysis (bill of materials) 5 Half Bricks 12x25x5,5 p 14350.

id descrizione um Q 6 Special thin bricks 25x2,5x5,5 p 5.

Main 1 Operaio Skilled labour specializzato h 0,6 7 Special angular pieces «L» 25x12x5,5 p 5.

Resource 2 Semiskilled labour h 0,6 8 Lime plaster mix mc 0,03.

3 Unskilled labour h 0,6 9 Waterproof painting l 0,3.

4 Bricks 12x25x5,5 p 49 10 Metallic scaffolding mq 1.

5 Half Bricks 12x25x5,5 p 7 11 Disk saw h 0,15.

6 Special thin bricks 25x2,5x5,5 p 5 The main resource is the critical Duration for execute an resource, the higher one.

7 Special angular pieces «L» 25x12x5,5 p 5 activity using a basic crew It represents the unit duration.

8 Lime plaster mix mc 0,03.

9 Waterproof painting l 0,3 (Basic crew duration) = D.

10 Metallic scaffolding mq 1 activity.

(N° of crews)x(IF).

11 Disk saw h 0,15.

IF < 1 -> The total cost increases, but also the unit cost increases interference factor.

IF = 1 -> Direct cost will remain equal: the number of crews increases but there’s no If the site isn’t so big there interference, half time but double people! The indirect cost decrease, because the total could be interference! 31 dime for execution of the project decrease, we’ll rent for a lower time the equipment) Giuseppe Rigamonti -

9th October 2020

Work scheduling

Cost and time are strictly related, so they must be integrated to optimize the performances of the project.

While planning is vertical, WBS, scheduling is horizontal. Scheduling takes the vertical breakdown and put it in horizontal, in order to have it in time dimension.

Time and cost are defined by resources, if I have time I have work, and work is executed by resources.

Estimation phase and target specification

Works scheduling.

Target specification steps.

• P.1 From technological to operational design.
• P.2 Work planning - WBS.
• P.3 Cost breakdown structure - CBS.
• P.4 BoQ, Resource Analysis, Total resources calc.
• P.5 Budget estimation It’s very important also to define who is responsible for each cost.
• P.6 Responsibilities assignments, Cost and controlling centers.
• P.7 Works scheduling.
• P.8 Resources scheduling.

Resource diagram 2 Giuseppe Rigamonti -

WBS match OBS organizational breakdown structure of the company, organization chart of a company, where we define the team responsible for the execution of the different activities.

We have to identify the responsible for the whole project.

There’s only one technician who is responsible for a specific activity/package of activities, for example for structure or plants.

WBS + OBS define controlling centers.

Main resource: resource that determine the activity duration:

• Labor.
• Machines/rentals.
• Subcontractors.

For example, for excavation/digging the resource which determine the duration of the activity is the machine, it’s yield/productivity.

Sometimes it’s not the labor of people that directly influence the duration of activity, but labor of worker that work for other company: subcontractor when there’s a specific work for which it’s necessary to have a company that do only this specific activity.

In order to reduce the activity duration, I can increase the number of crew, but if I have interference IF between different crews, so I have to take into consideration a lower productivity of the crew.

NB: In construction market the future isn’t conceived in a deterministic “dimension”, because every time we have to face with new construction site, new context and so on; so it’s necessary to look to the future and to the duration of a project, through a probabilistic approach.

WBS duration table

WBS l.1 l.2 l.3 Voce computo Durate Durate x 1 sq n° sq Fatt int Durate acc Approx.

1 cantiere h gg gg gg.

1 1 strutture di fondazione -10% 20%.

a cls di sottofondazione 400,0 50,0 50,0 4 0,7 17,85714286 18 16,2 21,6 18,3.

b cls rck ↓ Tn To Tp Median (50%) ↓.

c casseri Interference factor! ↓ ↓.

Using this my scheduling will.

d ferro Deterministic duration I put 4 crews in order to reduce the became a probabilistic schedule duration of 50 gg, which is too To reduce the number of days of the 10% Tp increase the duration of the 20%.

How to transform a deterministic duration in a probabilistic duration?

It’s necessary to take into consideration three different durations:

• Normal duration.
• Optimistic duration.
• Pessimistic duration.

The result is a probabilistic duration.

We can do it through this formula: Median duration with 50% probability = (To + Tp + 4Tn)/6.

Input data for work scheduling:

• WBS.
• Operational plans, description of how the activities are executed.
• Knowledge about relationship among activities.
• Activities duration.

With these four inputs I can start work scheduling: the tool to translate the operational design in a temporal scheme.

Goal:

• During estimation Check if my company can respect the time that the contract required.
• During building and controlling phase Monitor when each activity start and finish.

All the methods used to do it are graphical:

• Gantt, bars scheduling: bar diagram technique.
• Pert, network scheduling, through it we manage:
• Activity, they require the consumption of time and resources.

NB: The length of the arrows are not proportional to the activity duration.

• Event, It’s a moment of the works scheduling with an assigned DATE.

The longest path determines the duration, it’s called critical path.

• MPM, the evolution of scheduling is, it mixes the network logic of pert with the graphic advantage of Gantt.

23rd October 2020

Basic crew

Minimum number of labour that we need to execute an activity for the specific construction site.

Basic crew duration: duration for execute the activity with only one crew.

Network diagram – PERT

It shows as:

• Activity.
• Event.

There’s only one event that is the initial event and only one that is the final event, in the middle of these two important activities we have different activities: paths.

We have different paths:

• Consecutive activities: predecessors, successors.
• Parallel paths.

The duration of the whole project depends on the duration of paths.

Relationship rules:

• Technical-operational reasons,

The relationship between predecessor and successor is tied and cannot be changed.

Ex: casting and the concrete.

• Organizational reasons,

The relationships between predecessors and successors are chosen according to the specific organizational needs and can be different site by site.

Works scheduling: floats

Floats are a sort of “free time slots” that can be used by activities and events.

3,5 + 2 = 5,5 -> linked float = 6 - 5,5 = 0,5.

It’s a linked float because a1 and a4 share it.

Free float = 0 a ; 6T max T min 2 Linked float = 0,5 41 Total float = 0,5.

E 0 0 a ; 3,5 I 1 a ; 2 E 4 3,5 61 a ; 1,2 a ; 6 E 6 6 342 2 I 6 E 10,5 10,53 a ; 4,57 E 13,6 9,5 a ; 6,34 5 E 14,8 14,8 F3F a ; 4,38.

10,5 - 6,3 = 4,2 -> free float 10,5.

This is