TOC – Critical chain

Ing.J.Skorkovský, CSc,
Department of Business Management
FACULTY OF ECONOMICS AND ADMINISTRATION
Masaryk University Brno
Czech Republic

  BSD of  Microsoft
BSD=Business Solution Developent
  Copenhagen
  Fargo USA
   Busines Central
 development project
  BC Solution Center Czechia
  BC Solution Center Germany
  BC Solution center
France
  Nuclear enginering company Pilsen
   Porchse Maschinenfabrik
   Imprimantes du Figaro
Resellers
Customers
Implementation
    projects
Request  for Proposal
BC Delivery
Localization of
   BC project

Waterfall  methodology–Big design up front, milestones,..no iterations !!
It is based on prediction
Agile  methodology– Scrum (Sprints,..)- iterations approach
Critical Chain- based on TOC methodology
(see https://www.youtube.com/watch?v=mpc_FdAt75A )
Prince2  - Projects In  Controlled Environments (rolling wave planning)
Lean management
Different approaches to Project Management
Our PWP


They exceed the planned budget
They are not completed on time
Not everything that was required is delivered or the volume of delivery is reduced

TOC concisely I (see PWP presentation about TOC)
•
•
•origin: Eliahu Moshe Goldratt, Jerusalem
•cost world<->throughput world
•analogy weight of the chain – solidity of the chain
•how to find a bottleneck? ->  CRT
•tools of TOC – tree structures (5 trees)
•Five TOC steps
•CRT – EC – TT – PT – FRT  meaning:
•Current Reality Tree  - Evaporating Cloud Tree– Transition Tree  -
•   - Prerequisite Tree – Future Reality Tree
A modest repetition of TOC, because the theory of the critical chain
is built on this theory

TOC concisely I (see PWP presentation about TOC)
•bottleneck in the project management is a critical path (so no one resource only)
•finding (assessment) of bottleneck is not easy and often it is not explicit (uncompromising)
•everybody knows something about TOC  and nobody knows how to implement it to the real world- and
this is again another bottleneck (tendon of Achilles from the heel to the nape)
•

TOC-five steps (revision)
•Five steps process:
•            Step 0.   Identify the Goal of the System/Organization
Step 0.5 Establish a way to measure progress to Goal
•
•Step 1.  Identify the system’s constraint.
•Step 2.  Exploit the system’s constraint.
•Step 3.  Subordinate everything else to the above decision.
•Step 4.  Elevate the system’s constraint.
•Step 5.  If a constraint is broken (that is, relieved or improved), go back to  Step 1. But don’t
allow inertia to become a constraint.
•

Linear image of very simple project
•activities – abscissas – Gantt graph
•constantly changing conditions (Parkinson low, Murphy low, Student syndrome, customer changes -
„fancies “,“caprices“.. ….  ),
•
•
Solvina z Austrálie
Trouble
Trouble
Ajtík z Autsralie 20020416
Next slides

Parkinson´s law
•Parkinson's Law is the old  „folk wisdom“ that work expands to fill the time allotted. •Put
simply, the amount of work required adjusts (usually increasing) to the time available for its
completion. •The term was first coined by Cyril Northcote Parkinson

Parkinson´s law
Cyril Northcote Parkinson – Drops of Wisdom


Parkinson´s laws
•Work complicates to fill the available time
•The demand upon a resource tends to expand to match the offer of the resource. The reverse is not
true.
•

Student syndrom
 Professor: "Do you know how long it will take you to become fluent in Japanese?
 "Student: "I know, one night before the exam."

Parallel image of simple project



PlannerOne Scheduler- Central Business Central Application



PlannerOne Resource Planner



Project and its budget
•price of the whole project (see MS Dynamics BC on next slide)
•project length (time) – duration
•project stages and length of each activity (task)
•assigned resources to every activity and their capacities (time per defined period)
•time reserves (buffers-time reserves) and
•     estimation of the buffer sizes
•unfavourable influences (see Murphy´s lows - http://murphy.euweb.cz, etc.)
•additional activities (unexpected costs)
•
•
•
•

Murphy´s law



Selected Murphy´s laws
•If your attack is going well, you have walked into an ambush (trap)
•Planner is alerted about modification of the plan exactly in the moment, when the plan is finally
adjusted
•To carry out  n+1 trivialities you need two times more time than time necessary to carry out n
trivialities (law 99 %)
•If anything can go wrong, it will
•Any given program, when running, is obsolete
•No matter how many resources you have, it is never enough
•

Projects (jobs) in  Buiness  Central



Projects and MS Business Central
List o tasks and related costs (scheduled and used)
Schedule :The planning line contains expected usage for the job that will not be invoiced to the
customer. You use this option if the costumer will be invoiced from a different planning line (of
type Contract or Both Schedule & Contract types), or if the expected usage for this planning line
is not chargeable.
 .
Contract :The planning line specifies an amount that should be invoiced to the customer,
but no usage relates to the line so far. You use this option if no schedule of usage has been
planned
 for the job, or if the expected usage for the job has been specified on different planning lines
 (of type Schedule).

Job=Project->BC terminology
Home study

Projects in Business Central
Resource and
assigned capacitiy
Hours and resource

Resources and orders
Matrix structure of multi-project environment – responsibility
of project managers and responsibility of department managers are in conflict
time
capacity
Order 1=O1
Order 2 =O2
Project manager 1
(manages O2
Project manager 2
(manages O1)
Chief 1
Chief 2
overload
0789209039

Probability– median an element of statistical file,
 which is after sorting in the middle .Median of the set (1,5,2,2,1)  is 2

5 min        15min                                               45min
100 „5-miniutes meeting happened.
How many times it took 5 minutes only ?
Variability of the real time assigned to activity

Colleague ask for a quick rendez-vous: „Do not worry, it will take maximum 5 minutes!“.
How long it takes on average?
Partial time of any activity in the project

Probability of finishing tasks A to E  in time  is 50%. (50*50*….*50=3,125 %)
What is a probability, that task F will start in time ?
A
B
C
D
E
F
50%
3%
50%
50%
50%
50%
      How the timely finishing of the tasks A,B,C and D will influence the integration point ?
a)saving are fully wasted
b)delay in one task will be immediately transferred to the next project task (activity) see +10
-2
-5
-1
-7
+10
+10
Project environment is very complicated because of integration linkages and their dependencies

Project environment is very complicated because of integration linkages and their dependencies I
G
G
G
B
B
B
In order to start  B in the upper branch, you have to finish G and also B in the lower
branch. The probability, that B start in time is  50 % worse, than it was shown
on the previous slide.

Probability– median an element of statistical file,
 which is after sorting in the middle .Median of the set (1,5,2,2,1)  is 2

 50 %
Median


Further options for setting the duration of the activity (Task) I.
Time
Pesimistic estimation
due to the bad experience
of past projects
 30 %
Rezerve = Buffer

Probability
 50 %
Median


Further options for setting the duration of the activity (Task) II
Time
Pesimistic estimation
due to the bad experience
of past projects
 30 %
Rezerve = Buffer
Active task
Buffer
Activity (task)

Two approaches to utilization (reserve-buffer placement)
Active task
Buffer
Active task
Buffer
 A project that has only one activity
 Due date of the project
Using the buffer
We do not use buffer
Start of the project
Start of the project

  Unexpected project troubles and their impact
Active task
Buffer
Buffer time not used
 A project that has only one activity
Original Due date
of the project
 Buffer penetrated
 Due date=OK
Project due date
not met
Start of the project
Start of the project
Active task


Resource Dependencies Across Projects
Project 1
A
B
C
D
E
H
I
J
F
G
Project 2
Operations  A , D and H are done by the same resource
Delays: If Op D on Project 1 is late, Op H on Project 2 also get delayed as its resource is blocked
on Op D
Gains: Even if Op D finishes early, the resource cannot start Op H as has to wait for Op F to
finish


Op = operation
Project environment is very complicated because of integration linkages and their dependencies II

The project must be protected against influences of breakdowns (troubles)
activity 1
activity 2
activity 3
B
B
B
B
= buffer
Standard estimation with protecting buffers for every activity
activity 1
activity 2
activity 3
buffer
1st step   :  every activity is shorten to 50 % of  its original time size.
2nd step :  critical path buffer at the end of the project
will have size of 50 % of the total sum of saved time
created by shortening all partial activities
istockphoto_245312-steam-train-buffer-close-up
Project buffer

Simplified scenario CPM and CCPM
Task1
Implicit Buffer 1
Task 2
Saved time
Implicit Buffer 2
Task1
Task 2
Explicit Buffer
Explicit = directly specified, opened
Implicit = hidden, internally defined, indirect
 CPM = Critical  Path Method
CCPM = Critical Chain Project Methodology

EC and project management
EC=evaporating cloud=see PWP related to TOC


Critical path,  adjoining branches of the project and adjoining buffers (AB)
Project buffer
Critical path
activity X
activity Y
AB
Adjoining project branch
Buffer serves as a safety tool to accumulate reasons
of expected and unexpected delays
activity 1
activity 2
activity 3

Critical Path (CP)
• Critical path is defined as the longest way   (meaning time) from the starting point of the
project graph to the ending point.
• Every project has at least one critical path

The rules of Critical Path:
• Every delayed task on CP will essentially  delay the whole project
•
• Truncation of duration of any task on CP will shorten whole project

Critical Path (CP)
•Critical Path Method, abbreviated CPM, or Critical Path Analysis, is a mathematically based
algorithm for scheduling a set of project activities. It is an important tool for effective project
management.

Critical Path (CP)
1
2
3
4
5
6
7
8
Projet network diagram = any schematic display of the logical relations of the project activities
(tasks)
 In every node there is both an activity
 description and an allocated resource

Critical Path (CP)
Building a CP diagram 1


Critical Path (CP)
Building a CP diagram 2
One node

Critical Path (CP)
Building a CP diagram 3
The task in the dependency area influences its successor Task ID

Critical Path (CP)
Building a diagram 4 – calculating the FORWARD PASS
Early Starts and Early Finishes dates are calculated by means of Forward Pass
ES
EF
13-7=6
16=7+6+3
Integration point.
B had to start
7 times units  later !!

Critical Path (CP)
Building a diagram 5 – calculating the BACKWARD PASS
Late Starts and Late Finishes dates are calculated by means of Backward Pass
LS
LF
18-2=16
16-3=13
13-3=10
13-2=11
10-3=7
16-3=13
13-3=10
Difference
Forward-Backward :
you can start
7 minutes later and the time
of the project (duration)
 is the same
Planüberhang,
Slip, Scivolo,
Regresso,
Загрузочный
περίοδοι απραξίας

Critical Path (CP)
Building a diagram 6 – calculating the FLOAT(SLACK)/CP
 Free Float (Slack): Amount of time a single task can be delayed
 without delaying the early start of any successor task =LS-ES or LF-EF

Slack=Float (home study)
Slack, in the context of project management, refers to the amount of time that a task or activity
within a project can be delayed without causing a delay to the overall project timeline.
It is also known as float or free float.
Slack is a critical concept in project scheduling and helps project managers and teams understand
the flexibility or free-space they have in managing individual tasks within a project.
Critical Path: The critical path in a project is the sequence of tasks
that have zero total slack, meaning any delay in these tasks will directly
impact the project's completion date. So there is no reserve

Simple project – Construction of the engineering plant
Building Construction - 90
Putting into service - 30
Contracts with suppliers - 15
Machine production - 90
Machine installation - 30
90
30
90 +30=120
15 +90=105
120-105=15
    Slack
15
90
30
 Late start
90
30
15
90
 Earlier start
Time not used
   (waiting time)
15
15
30

CCPM and Float and Buffers
Float 1
Float 2
Today – in order  to start ASAP (As Soon As Possible)
Modification
Buffer 1
Buffer 2
A huge multitasking problem for the project manager
Less parallel activities to manage

Slack=Float (home study)
Accurate description : Slack or Float provides flexibility in the project schedule. When used
correctly, project managers can shift activities and resources to meet the project objectives and
priorities better.
It is the amount of time an activity can be delayed without impacting other activities or the
project end date and changes throughout the project implementation.
Activity 1
  Project Due Date
Planner Software calculated as
Earliest Start Date
Today
Activity 2
Activity  3
Activity 1
Activity 2
Activity  3
Activity 1
Activity 2
Activity  3
Activity 1
Activity 2
Activity  3
Activity = tasks
Project due not met

Critical Path (CP)
• Project Planning and control.
• Time-cost trade-offs.
• Cost-benefit analysis.
• Reducing risk.
CPM is helpful in :

 Time-Cost Trade-off
The term "trade-off" in project management traditionally refers to the decision to create and
maintain a balance between the "time" and "cost" of a project.
The duration of a project can often be reduced by speeding up some of its activities at the cost of
additional (higher) resource costs.
There is a relationship between the time to complete a project and its cost.
For some types of cost, the time-cost relationship is in direct proportion.
For other types, there is a direct trade-off. The existence of these two types of costs allows
setting the optimal pace of the project and thus reducing costs.

Project crashing – reducing project implementation time
Project crashing  : you can achieve by reducing the time of one or more tasks (activities).
 However, this is associated with the allocation of additional resources to tasks
 It may result in shorter task times than originally planned, but,
  of course, it also increases the cost of the whole project.
Home study
Brooks’s Law is a principle in software
project management that states:
“Adding manpower to a late software
 project makes it later.”

Brook´s law
• Rump-up Time  : New team members need time to become productive
• Communication Overhead :  number of coomunication channeslk increases
• Limited Divisibility : Some  tasks cannot be easily devided among many people
KEY POINTS

Critical Path (CP)
Limitation of CPM :
• Does not consider resource capacities (very bad approach).
• Less efficient use of buffer time.
• Less focus on non critical tasks that can cause risk.
• Based on only deterministic task duration.
• Critical Path can change during execution.

Multi-project Management
w1
w2
w3
w4
w5
w6
w7
w8
w9
w10
w11
w12
w13
w14
DAP
Project 1














12
Project 2














12
Project 3














12

36
K1
K2
K3
w1
w2
w3
w4
w5
w6
w7
w8
w9
w10
w11
w12


DAP
Project 1














6
Project 2














6
Project 3














6
18
Bad multitasking  causes, that one project will be significantly longer
and no other project will be shorter

Multitasking characterization
•people always overestimate the length of their tasks
•salesman  offers impracticable terms (dates)
•The fight for reserves (capacities) causes, that all saved time is fully wasted (Student´s
syndrome)
•Reserves (if any) are used badly !!!!!!
•Bad use of reserves causes lack of transparent assignment
•Non transparent priorities are parents of bad multitasking
•Bad multitasking causes longer duration of all activities (tasks) and thus all the projects
•

CP definition (more in detail)
  Critical path is defined as the longest way   (meaning time)
  from the starting point of the project graph to the ending point
Critical path represents technological dependencies and given
times of every task on Critical path  inclusive of necessary
condition for fulfilment of foregoing  tasks (activities)
framed by integration points.

Critical Chain
Task
Resource and capacities

Contemplation I.
Computing power


Contemplation II.
E-mails
Parallel  telephoning
Parallel  problem solving

Contemplation III.
Is this the goal of my lifelong efforts?
Maybe not …. I guess
I reached another peak¨…

Critical chain definition
•   In TOC the Critical chain is defined as the longest way  (meaning time)  from the starting
point of the project graph (Gantt) to the ending point, which takes into account technological
dependencies  as well as time of the tasks and moreover, capacities of assigned resources.
•    With infinite capacities of resources you can consider Critical path=Critical chain

Critical Chain
•Critical Chain is a project management methodology and scheduling approach developed by Dr.
Eliyahu M. Goldratt, known for his work in the Theory of Constraints (TOC). •Critical Chain project
management focuses on improving the efficiency and reliability of project execution by addressing
common project management challenges.
•The primary components of the Critical Chain include:
•
See next slides

Project schedule
•Project Schedule: In Critical Chain, a project schedule is created by identifying the critical
path, the most extended sequence of dependent tasks and activities that determines the project's
overall duration. •Unlike traditional project management, the Critical Chain takes consideres the
availability of resources and buffers for the uncertainty approach

Resource Management
•Resource Management: Critical Chain emphasizes the need to effectively manage project resources
(human, equipment, materials). •It suggests that project managers should protect the project
schedule by not overloading resources and ensuring that resources are available.
•

Buffers
•Buffers: Critical Chain introduces the concept of project buffers to manage uncertainties and
variability in project execution. There are typically three types of buffers:
•Project Buffer: This is placed at the end of the project schedule to protect the project's overall
duration. It accounts for uncertainties in task durations and resource availability.
•Feeding Buffer: Placed before non-critical tasks. Such a  buffer protects the critical path by
ensuring,  that tasks on the critical path have the necessary resources to proceed.
•Resource Buffer: Placed before critical resources, this buffer protects against resource
constraints that could impact the project schedule.
•

Multi-project management and critical resources (CCR) used in more that one project branch
X
X
X
X
AB
AB
AB
AB


Project buffer
X
Disadvantageous variant
Critical chain
Critical path
CCR = Capacity Constrained Resource = X

Multi-project management and critical resources (CCR) used in more that one project branch
X
X
X
X
AB
AB
AB
AB


X
After transformation
of activities
Project buffer
Critical chain

Project management based on remainimg time in buffers – Buffer Management
•Buffers are used for timely warning and that is to say predicting  and avoiding future problems
related to project deadlines (milestones are  not met)
•
•It is also used as a guideline for corrective actions
•Buffers represent time reserves
•

Basic metrics showing the project status
•The partial size of Critical chain (CC) fulfilled in days (in  %)
•How much of buffer size was used to fulfil above mentioned partial size of Critical Chain?
•Trend of project (buffer consumption graph- see next slide)
•Consumption of the financial buffer –relation to budget
•Priorities – bigger buffer penetration- bigger priority
•Adjoining branches have always lower priorities
•It is not allowed to create bad multitasking
•

Trends of the project
%  use of the buffer
% consumption of the critical chain
Dangerous zone
Warning zone
Safety zone
peril print_guardian_angel_watching_over_children_bridge_litho pompier_009
Guardian angel

Trend of the project advancement – (another angle of view)
0 %
100 %
100 %       Time remaining till the end of the project   0 %
OK
Action plan
Action
Resource: DP R.Jurka (2006); taken from LEACH, L., P. (2004), s. 12.

Planning  - principles
•We are working with plan , which takes into account different times of tasks   :
•- start of the tasks are changed based on termination of preceding  tasks
- you have to react in project in such a way , that handover is done as a baton pass during races
A1
B1
C1
D1
B
Buffer
Plan with sharp deadlines with buffers 50% (2+3+3=8 8+4=12)
2
4
6
8
10
Planned start
12
Critical chain completion
8 days
0
100%
100%
Resource  MPM systems

      Buffer
Planning  - principles
•A1 did not started yet , because this A1 resource is still working on another order (task), which
may be part of another project
•B1 already started an for completion will need another two days
A1
C1
D1
r
2
4
6
8
10
Planned start
12
B1
0
100%
100%
Resource  MPM systems
Plan with sharp deadlines with buffers 50% (2+3+3=8 8+4=12)
Critical chain completion
8 days
1


Plan 2nd day after start
•A1 started and will be finished (completed) tomorrow.
•B1 will be finished (completed) tomorrow
A1
C1
D1
r
B1
0
100%
100%
2
4
6
8
10
Planned start
Plan with sharp deadlines with buffers 50% (2+3+3=8 8+4=12)
Critical chain completion
8 days
Buffer
12
Resource  MPM systems


Plan 3rd day after start
•A1 despite all efforts resource A1 needs another day to complete.
•B1 has completed his work with 2 days delay
A1
C1
D1
r
B1
0
100%
100%
Plan with sharp deadlines with buffers 50% (2+3+3=8 8+4=12)
Planned start
2
4
6
8
10
Critical chain completion
8 days
12
3
Buffer
Resource  MPM systems


 Plan 6 day after start
•A1 completed his task with 2 days delay
•B1 completed his task with 2 days delay
•C1 completed his task 1 day earlier than expected (planned)
•D1 will start to work tomorrow
A1
C1
D1
r
B1
0
100%
100%
Plan with sharp deadlines with buffers 50% (2+3+3=8 8+4=12)
Planned start
Critical chain completion
8 days
2
4
6
8
10
12
Buffer


 Plan 8 day after start
•A1 completed his task with 2 days delay
•B1 completed his task with 2 days delay
•C1 completed his task 1 day earlier than expected (planned)
•D1 needs one day more to complete
A1
C1
D1
r
B1
0
100%
100%
Plan with sharp deadlines with buffers 50% (2+3+3=8 8+4=12)
Planned start
Critical chain completion
8 days
2
4
6
8
10
12
Buffer

rezerva
Plan 11 day after start
•A1 completed his task with 2 days delay
•B1 completed his task with 2 days delay
•C1 completed his task 1 day earlier than expected (planned)
•D1 completed his task with 2 days delay
A1
C1
D1
r
0
B1
Plan with sharp deadlines with buffers 50% (2+3+3=8 8+4=12)
Planned start
100%
100%
Critical chain completion
8 days
2
4
6
8
10
12
11

https://www.youtube.com/watch?v=4ARI1qIG1vA

Example of using real SW package to control project by CCPM methodology
                                                    (home study)
Use of Add-on Prochain to MS Project Application
After setup of all times
Critical chain is red one

Levelling (balancing)
Task A
Task B
Resource X
Resource X
Before - >  tasks and assigned (scheduled)  resources
After
Task A
Task B
Resource X
Resource X
A resource cannot perform two actions at the same time !!!

Time distribution
 Time
10 days
18 days
Buffer size
Buffer size = 8 days

Project Quick, resources A-E and activities X,Z,X,W, and V
Resource and Activity
Activity = Task
A - Y
Median of the required
 time
10 days
You can say, that 50 % of any activities finish earlier, and other 50 %
will be delayed, meaning, that 10 days represents 50 % of the estimated time
for chosen aktivity (task).
Project managers decided, that activity ends if 90 % of estimated time
will be consumed. It means, that they add for the safety reasons a time buffer of 8 days
10 d= 50%, 20d=100%, 2d=10%, 20d-2d=18d=90%, 18d-10d=8days
A - Y
B  -Z
C - X
D - W
E - V
5 x 10 days=50 days
(90 %)
5 x 18 days= 5 x (10+8)=90 days
(50 %)

Five activities (tasks)
 and applied modifications
•If we consider for every activity time buffer 8 days we will get :
A-Y
B-Z
C-X
D-W
E-V
5 x 10 days= 50 days
A-Y
 8
B-Z
 8
C-X
 8
D-W
 8
E-V
 8
5 x 18 days= 5 x (10+8)=90 days

Vložte obrázek některého z významných geografických úkazů země.

Five activities and modifications (added buffers) and four types of troubles
A-Y
 8
B-Z
 8
C-X
 8
D-W
 8
E-V
 8
A-Y
B-Z
C-X
D-W
E-V
Delayed
„reporting“
We wait for resource D
 (even if C finished earlier)
Parkinson
Real delay
No one trouble causes project delay taking into consideration
planned delivery date  (agreed date  of the project).
Dissipation of acquired time reserves was caused by company strategy saying
strictly stick to the planned project schedule (example of rigid management)
5 x 18 days= 5 x (10+8)=90 days

Five projects after modification (buffers united to one and placed to the  end of the project)
A-Y
B-Z
C-X
D-W
E-V
 8
 8
 8
 8
 8
A-Y
B-Z
C-X
D-W
Parkinson
Little bit longer than 20 days median
but shorter than 18 days
 Earlier end of
activity A
 8
 8
 8
 8
 8
= CPB=current project buffer = 40 days
 8
 8
 4
= new buffer = 50 % out of CPB, which makes CPB/2
E-V

Critical path- Critical chain
START
Activity V
14 days, resource A
Activity W
6 days, resource B
Activity X
6 days, resource C
Activity Y
10 days,
 resource A
Activity Z
4 days,
 resource D
END
Critical path
Critical Chain
Project is considered as successful if is finished in expected time
 and financial budget is not exceeded

Critical chain with buffers
START
Activity V
7 days=14/2, RES  A
Activity W
3=6/2 days, RES B
Activity X
3=6/2 days, RES C
Activity Y
5=10/2 days, RES A
Activity Z
2=4/2 days, RES D
END
>
Adjoining
buffer
1,5 days
>
Project
buffer
7 days
7=(7+5+2)/2
Length of the Critical Chain (white line):
7+5+2+7=21
and  originally it was all in all 28 days
>
Adjoining
buffer
1,5 days

 Project 2
    Buffer (10)
Buffer consumption
Activity A(10)
Activity B(10)
Project 1
    Buffer (10)
Activity A(5+8)
Activity B(10)
Buffer penetration  = 3 days
10=(10+10)/2
Rate of penetration is used to assign priorities to the partial activities

Project Buffer 2
Priorities assigned to resources
•If one resource have (red A) to be assigned to two activities starting in the same moment, so the
first activity which will start is the one belonging to the project with bigger project buffer
penetration (Project 2).
•If none of all project buffers were penetrated with previous activities, so the first starts this
activity which belongs to the critical chain.
A 1

AB 1


AB 2
A 2
A2 starts firstly because PB 2 is partially consumed (penetrated)
AB-Adjoining Buffer
PB-Project  Buffer

Project Buffer 1

Priorities assigned to resources
A 1
    Project
     Buffer 1

AB  1


AB 3
           A 2
A 2
DFB 3
AB 2
Critical chain
 This activity (A1) starts first because it is a part of the Critical chain
and Project Buffer 1 is penetrated

AB-Adjoining Buffer
PB-Project  Buffer
Project Buffer 2

A1 (P1) -> A2 (P1) -> A2 (P2)

Main benefits of the Critical Chain (CC) usage
• All projects applying the CC methodology will end earlier than projects being managed by any
other method
•
•Promised delivery times are fulfilled with higher rate of credibility
•
•You will have more free capacity of all used resources
(Home study)

Main benefits of the Critical Chain (CC) usage
•Better initial estimation about project timing and thus bore accurate planning
•
•You won't encounter any problems when initiating projects, because you always take into
considerations the limitations imposed by the drum type resource
•
•Decrease of unfavourable effects such  as  Student syndrome, Murphy attacks and impacts of
Parkinson´s laws by redeployment and integration of all buffers to one and only one project buffer
at the end of the project
•
•Utilization of benefits (saved time and capacities of the resources) caused by earlier ended
activities
•
•
(Home study)

project-manager-attributes



Waterfall  methodology–Big design up front, milestones,..no iterations !!
It is based on prediction
Agile  methodology– Scrum (Sprints,..)- iterations approach
Critical Chain- based on TOC methodology
(see https://www.youtube.com/watch?v=mpc_FdAt75A )
Prince2  - Projects In  Controlled Environments (rolling wave planning)
Lean management
Different approaches to Project Management

Waterfall  - predictive approach
Clients may not know exactly what their requirements are before they see working software and so
change their requirements, leading to redesign, redevelopment, and retesting, and increased costs
One of the differences between agile software development methods and waterfall is the approach to
quality and testing. In the waterfall model, there is always a separate testing phase after a build
phase; however, in agile software development (see next slide) testing is completed in the same
iteration as programming

Agile PM approach – for instance SCRUM (relation to RFP)
Scrum is an iterative and incremental agile SW development
framework for managing product development
A key principle of Scrum is the dual recognition that customers will
change their minds about what they want or need
(often called requirements volatility) and that there will be unpredictable
challenges for which a predictive or planned approach is not suited
Sprint->Stage
Scrum ->Iteration, daily work
Request for Proposal

SCRUM



•    Some slides to complete presentation – final review



11-98
Critical Chain Solutions
John
Feeder Buffer
Feeder Buffer
Feeder Buffer
ProjectBuffer
John
John

Drum principleDrum – system-wide constraint that sets the beat for the firm’s throughput
Drum prinicple- CCPM)
(CC=Critical chain)
Drum – sets the beat (pace, tempo) for the firm’s throughput ->constraint
Drum – could be person, department, policy, resource
Capacity Constraint Buffer (CCB) – safety margin between projects
Drum buffer (DB) – extra safety before the constraint CCR (DRUM)
Project 1 buffer
CCB
Project 2 buffer
Project 1 buffer
DB
Constraint (CCR)

1.
Project management and  Drum (Capacity Constraint resource= CCR )  - principle  of schedule
projects based on drums
A principle that is very similar to the five steps of TOC, where the term Drum replaces the term
Bottleneck
1. Identify the drum (bottleneck)
2. Exploit the drum
- Prepare a project schedule for ech project
- Determine priority for the drum
- Create the drum schedule
3. Subordinate the project schedules to steps 2 and 3
4. Elevate the capacity of the drum
5. Go back to step 1
Schedule project based on Drum concept ->Designate Critical Chain (CC)->
->Insert Drum buffer before capacity constraint resource (Drum) >Resolve conflicts

Difference Between Buffer and Float (or Slack)  - (home study)

People often get confused between buffer and float. They find these two terms similar, however,
they are not.
The following are a few differences between the float and buffer:
•Float  (slack) is a critical path phenomenon, while buffer belongs to the critical chain.
•
•A float (slack) is a difference between the duration of the critical path and the non-critical
path.
•
•A float is zero on a critical path.
•
•A buffer is based on contingencies (unpredictable actions). For example, the project buffer is
about 50% of the safety time that you have removed from the activity estimate duration. Based on
the definition of buffer, it is not zero on a critical chain or any other chain.
•
•A float is the same for all activities on a non-critical path, any activity can consume it
partially or fully, and other activities can utilize balance. There is no further analysis.
•
•Any activity can also borrow a buffer if the activity is delayed. The project manager analyzes the
remaining buffer to find the status of the project.
•
•Buffers can be divided into three categories: project buffer, feeding buffer and resource buffer

http://www.fortezzaconsulting.com/blog/5-myths/
https://www.workflowmax.com/blog/choose-your-project-management-methodology-pros-and-cons-of-agile-
waterfall-prism-and-more
Very usefull one :
https://www.tutorialspoint.com/management_concepts/pareto_chart_tool.htm

101 Silly Math Jokes and Puns to Make Students Laugh Like Crazy | Prodigy Education



Obsah obrázku osoba, stojící, vlasy, pózování Popis byl vytvořen automaticky
The author of the material thanks you very much for your attention