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Activity-Flow Work Structuring Method
J u l y, 2 0 1 9
N e l l y G a r c i a - L o p e z
K u m a g a i P r o f e s s o r o f E n g i n e e r i n g a n d
D i r e c t o r o f C I F E , S t a n f o r d U n i v e r s i t y
P r o f e s s o r, U n i v e r i d a d C a t ó l i c a d e C h i l e
P r o j e c t D i r e c t o r, G r u p o G a l o p a
L u i s F e r n a n d o A l a r c ó n
M a r t i n F i s c h e r
Nelly Garcia-Lopez, Martin Fischer, Luis F. Alarcón – [email protected]
Activities require a set of flows to be executedFaçade brick construction (Frederikskaj project)
Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
Labor
Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
MaterialsLabor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
PrecedenceLabor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
Workspace
2m around building perimeter
Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
Bricks
Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
InsulationLabor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
Mortar
Brick
layer
Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
Windows
(Koskela 1999)
Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
EquipmentAligner
Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
Brick
layer
Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
Hammer
Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
Information
Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
External
(Bertelsen et al. 2006)
Nelly Garcia-Lopez, Martin Fischer, Luis F. Alarcón – [email protected]
Make-ready process = Ensure activities in plan are sound
•Make-ready increases planning reliability by:• Identifying and removing activity constraints
• Committing to “sound” activities
•Case study make-ready process: ≈ 80% of weekly meeting
(Ballard & Howell 1998)
3
Nelly Garcia-Lopez, Martin Fischer, Luis F. Alarcón – [email protected]
On-site flow
Can the field managers track readiness of all flows?
Reason for non-completion % related to flow
Off-site On-site
Predecessor 50.60%
Labor availability 4.50% 14.54%
Change of priority 13.90%
Equipment availability 8.23%
Equipment overcapacity 3.90%
Information unavailable 1.73%
Quality inspection failed 1.73%
Materials delivery 0.43%
Underestimated 0.43%
Total 14.89% 85.10%
On-site flows
Activity 3
Released by upstream activities
Activity 2
Off-site flowsDelivered to the jobsite
Activity 1Off-site flow
e.g., concrete crewe.g., concrete delivery
Most reasons for non-completion relate to on-site flows
Nelly Garcia-Lopez, Martin Fischer, Luis F. Alarcón – [email protected]
Current construction models do not represent all the flows
Build deck
form Area 1
Install slab
rebar Area1
Pour slab
Area 1
Build deck
form Area 2
Install slab
rebar Area 2
Pour slab
Area 2
Date line for
Weekly planning
Field managers commit to activities based on readiness “perception” (Pikas et al. 2012)
What flow?
Flow performance?
Flows ready?
Is activity sound? (Ballard 2000)
Nelly Garcia-Lopez, Martin Fischer, Luis F. Alarcón – [email protected]
Build deck
form Area 1
Install slab
rebar Area1
Pour slab
Area 1
Build deck
form Area 2
Install slab
rebar Area 2
Pour slab
Area 2
Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
Date line for
Weekly planning
Proposed activity-flow construction representation
Nelly Garcia-Lopez, Martin Fischer, Luis F. Alarcón – [email protected]
Build deck
form Area 1
Install slab
rebar Area1
Pour slab
Area 1
Build deck
form Area 2
Install slab
rebar Area 2
Pour slab
Area 2
Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
Labor
Workspace
Precedence
Materials/components
Information
Equipment
External (Permits, inspections)
Flow Key:
Date line for
Weekly planning
Proposed activity-flow construction representation
Flow type: Labor
Flow class: Concrete crewWhat flow?
Flow performance? Flow failure %: 80%
Avg. flow delta: 2.2 days
Flows ready?
Is activity sound?
Prob. flows ready: 90%
Nelly Garcia-Lopez, Martin Fischer, Luis F. Alarcón – [email protected]
Objective - Develop activity + flow - based model to:
Formally manage
activities and flows
Make data-driven
decisions
e.g., Resource and buffer sizing
Predict delays in downstream
activities
Nelly Garcia-Lopez, Martin Fischer, Luis F. Alarcón – [email protected]
1
predecessor
if(! isOffsite &
! isPrerequisite)
if(isWorkspace)
Computational representation of the AFM
ActivityType
activityTypeName <CA>
uniformatL4
Activity
activityName
plannedStart
plannedFinish
actualStart
actualFinish
Flow
flowType
flowStatus
dueDate if[isOffsite]
dateReady if[isOffsite]
predPF
predAF
ReasonFor
Variation
reasonForVariation
Stakeholder
stakeholderType <R>
company
*
LaborFlow
flowName(Ballard 2000)
EquipmentFlow
flowName
MaterialFlow
flowName
WorkspaceFlow
flowName
InformationFlow
flowName
ExternalFlow
flowName
actReasonVar
if(i
sL
ab
or)
if(i
sE
qu
ipm
ent)
if(isMaterial)
if(isInfo)
if(i
sE
xte
rna
l)
timeBuffer
flowDelta
flowImpact
flowReasonVar
1
actStake
1
1flowStake
deltaStart
deltaDuration
deltaFinish
Garcia-Lopez 2016
Nelly Garcia-Lopez, Martin Fischer, Luis F. Alarcón – [email protected]
Developed Activity-Flow App
Nelly Garcia-Lopez, Martin Fischer, Luis F. Alarcón – [email protected]
Work structuring + Production control
Work structuring Weekly planning and control
Activity + Flow
Structuring
Method
Update look-
ahead and
weekly plan
Carry out daily
tracking
Present analytics
in weekly
planning meeting
Transform
schedule into
Activity-Flow
representation
Set-up meeting on
Fredrikskaj project
Collaborative look-
ahead update on
Equilibrium project
Tracking using mobile
device on Fredrikskaj
project
Weekly planning
meeting on Ichma
project
Nelly Garcia-Lopez, Martin Fischer, Luis F. Alarcón – [email protected]
Definition:
• Work structuring entails connecting the facility design (product) with the processes, typically in the form of schedules, used to deliver the physical facility (Ballard et al. 2001; Tsao et al. 2004)
Research Question:
• How can we extend existing work structuring methods (e.g., Takt planning and Ballard’s Lean method) to enable field managers to structure all the construction flow types and generate activity-flow schedules?
Work Structuring: Definition + Gaps
Nelly Garcia-Lopez, Martin Fischer, Luis F. Alarcón – [email protected]
Research Methodology
Theoretical Point
of Departure
AFWSM
development
Validation in 3 projects(Thomsen et al. 1999, Ho et al. 2009)
Field observations
AFWSM Testing
Nelly Garcia-Lopez, Martin Fischer, Luis F. Alarcón – [email protected]
Activity-Flow Work Structuring Method (AFWSM)
• Consists of 7 steps that allow field managers to visually represent activities and flows in a construction fragnet or process
• Example:
Fragnet: Build
concrete structure
Nelly Garcia-Lopez, Martin Fischer, Luis F. Alarcón – [email protected]
AFWSM: Step 1 – Define fragnet’s prototypical activities
Install column
rebar
Install column
forms
Pour column
concrete
Install slab
rebar
Install slab
scaffolding
Pour slab
concrete
EXAMPLE:
Fragnet: Build concrete
structure
Nelly Garcia-Lopez, Martin Fischer, Luis F. Alarcón – [email protected]
AFWSM: Step 2 - Sequence fragnet’s prototypical activities basedon precedence constraints
Install column
rebar
Install column
forms
Pour column
concrete
Install slab
rebar
Install slab
scaffolding
Pour slab
concrete
Nelly Garcia-Lopez, Martin Fischer, Luis F. Alarcón – [email protected]
AFWSM: Step 3 – Identify workspaces and their sequencing
Zone 1
Zone 2Zone 3
Zone 4
Nelly Garcia-Lopez, Martin Fischer, Luis F. Alarcón – [email protected]
AFWSM: Step 4 – Identify on-site flows
Install column
rebar
Install column
forms
Pour column
concrete
Install slab
rebar
Install slab
scaffolding
Pour slab
concrete
Zone n Zone n+1
Install column
rebar
Install column
forms
Pour column
concrete
Install slab
rebar
Install slab
scaffolding
Pour slab
concrete
Rebar crew
Rebar crew
Carpentry crew
Carpentry crew
Concrete crew
Concrete crew
Nelly Garcia-Lopez, Martin Fischer, Luis F. Alarcón – [email protected]
AFWSM: Step 5 – Identify off-site flows
Concrete pump
Concrete pump
Rebar
Zone n
Install column
rebar
Install column
forms
Pour column
concrete
Install slab
rebar
Install slab
scaffolding
Pour slab
concrete
Concrete
Concrete
Inspection
Rebar
Loading permit
Nelly Garcia-Lopez, Martin Fischer, Luis F. Alarcón – [email protected]
AFWSM: Step 6 – Identify interfaces with other fragnets
Level
released by
self-climbing
scaffold
Zone n
Install column
rebar
Install column
forms
Pour column
concrete
Install slab
rebar
Install slab
scaffolding
Pour slab
concrete
Nelly Garcia-Lopez, Martin Fischer, Luis F. Alarcón – [email protected]
AFWSM: Step 7 – Identify stakeholders responsible for the flows
Install column
rebar
Install column
forms
Pour column
concrete
Install slab
rebar
Install slab
scaffolding
Pour slab
concrete
Zone n Zone n+1
Install column
rebar
Install column
forms
Pour column
concrete
Install slab
rebar
Install slab
scaffolding
Pour slab
concrete
Rebar crew
Rebar crew
Carpentry crew
Carpentry crew
Concrete crew
Concrete crew
Rebar
Level
released by
self climbing
scaffold
Concrete pump
Concrete
Concrete pumpConcrete
Inspection
Rebar
Loading permit
Nelly Garcia-Lopez, Martin Fischer, Luis F. Alarcón – [email protected]
Field managers can use the AFWSM’s outcome to createactivity and flow-based schedules
Activity + flow – based schedule
Nelly Garcia-Lopez, Martin Fischer, Luis F. Alarcón – [email protected]
Project Ichma Equilibrium Frederikskaj
Building type + phase Office/Structural Residential/Foundations Residential/Finishes
Test period 18 weeks 4 weeks 4 weeks
# Fragnets 5 3 3
AFWSM implementation results
# Activity types 26 11 28
# Flows 85 31 80
Avg. Time (mins) 17 10 18
65
15
196
Total
9
Nelly Garcia-Lopez, Martin Fischer, Luis F. Alarcón – [email protected]
Feedback from field management teams
“Identifying and mapping the flows in a visual way
allows all of the contractors to be on the same page
and understand the plan better” Project
Superintendent Frederikskaj
“Keeping track of the historical flow performance is
key. We might have a hunch about what flows are
consistently late, but we don’t have the data to
identify performance issues.” Project Engineer Ichma
“Its very useful that we now have a tool that formally
maps the flows that are needed to execute an
activity … we think about these things, but there is
no formal tool that allows us to check that all the
flows are ready so the activity is not in danger.”
Project Engineer Ichma
Nelly Garcia-Lopez, Martin Fischer, Luis F. Alarcón – [email protected]
Conclusions and Future Work
Conclusions:
• Considering flows during work structuring enables better understanding and communicationof the plan among stakeholders
• The Activity-Flow Work Structuring Method (AFWSM) enables field managers to formallyrepresent and manage flows
• The AFWSM should lead to schedules with higher planning reliability since flows should be better synchronized between activities
Future Work
• Testing effect of work structuring method on schedule performance
• Developing methods for automating / speeding transformation from work structuring toactivity-flow-based schedules
Nelly Garcia-Lopez, Martin Fischer, Luis F. Alarcón – [email protected]
Questions?
Thank you!
Nelly Garcia-Lopez