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Land Transport Authority
We Keep Your World MOVING. We Keep Your World MOVING. We Keep You
MOVING. We Keep Your World MOVI...
OUTLINE
Top Down vs Bottom Up
method in construction
• TIME comparison
• COST analysis
Earth Pressure Balance TBM
• OPEN C...
C937B Tai Seng Facility Building
C929
Kaki Bukit
Station
(Top Down)
C929A
C928
Bedok North
Station
(Bottom Up)
C928
C929A
...
Rate of volume
of earth to be
excavated (20m)
$129/m3
$99/m3
Rate of concrete
to be used for
roof slab (1.5m)
$150/m3
$150...
Rate of volume
of earth to be
excavated (20m)
$129/m3
$99/m3
Rate of concrete
to be used for
roof slab (1.5m)
$150/m3
$150...
Reasons for higher cost of Top - Down
• Limited construction openings for handling materials and
machineries.
• Limited he...
Tunnel Alignment
Expo Bound
Bukit Panjang Bound
C929A Station Box
C929
C928
WEST Cut and Cover Tunnel Alignment
START
END
EAST Cut and Cover Tunnel Alignment
C927
Expo Bound
Bukit Panjang Bound
Station Box
C928
START
END
Key Position
Selection
KEY position 7 to
11 are not used
because
• It is difficult to
install as
Connection
Segments (B)
and Standard
Segments (A...
Required Information
• Straight portion of the
Tunnel
• Tunnel is moving UPWARD
L16 R2, R5, R14
SUSTAINABLE DEVELOPMENT
Choose efficient formwork
Timber Formwork System Formwork
Material Timber & Plywood Aluminium
Durability 20 times 120 – 15...
Environmentally Improved Materials
• Using MILLED WASTE for temporary pathway instead of
concrete.
• Using factory prefabr...
Learning Outcomes
Challenges
Encountered
Bedok North
Station
(1) Water Canal
Diversion
Temporary Canal
HDB
D-WALL
SBP
In case of any failure...
Bedok North
Station
Challenges
Encountered
(2) Water Ingress
Stock pile
Water squeeze out from
underground into the statio...
Kaki Bukit Station – Challenges Encountered
Restriction
in space
• Top 2 metres
from ground
had scattered
services lines
t...
Why is there a discontinuity in the
coupler position ?
Presence of WATER STOP
Plan View
Elevation View
Water Stop
Stop End
Couplers
D - Wall
Why is there a
rope hanging
in a Slurry
Storage Tank
?
Desander
float
marker
Excavated area
Slurry
Storage
tank
marker
float
Construction Market
Activity Cycle Model
Where WE stand ?
Peak
Zone
Mid Zone
Trough Zone
GROWTH DECLINE
Apartment
Industrial Building Offices, HotelCIVIL
agnes kamsiah
CK SIMON
KINSKI
SELVAKUM
AR
MOD
YOU
GEN
SHAWN
Thank
you
Internship_report
Internship_report
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Internship_report

  1. 1. Land Transport Authority We Keep Your World MOVING. We Keep Your World MOVING. We Keep You MOVING. We Keep Your World MOVING. We Keep Your World MOVING. Internship Presentation DEVARSH KUMAR 3rd year undergraduate Department of Civil Engineering Indian Institute of Technology Madras email – devarsh10iitm@gmail.com
  2. 2. OUTLINE Top Down vs Bottom Up method in construction • TIME comparison • COST analysis Earth Pressure Balance TBM • OPEN CUT TUNNEL alignment of C928 • KEY position selection Sustainable Development • Environmentally improved material Learning Outcome • Challenges encountered • Site photos with description • Construction Market Activity Cycle Model
  3. 3. C937B Tai Seng Facility Building C929 Kaki Bukit Station (Top Down) C929A C928 Bedok North Station (Bottom Up) C928 C929A C929A Layout Chart
  4. 4. Rate of volume of earth to be excavated (20m) $129/m3 $99/m3 Rate of concrete to be used for roof slab (1.5m) $150/m3 $150/m3 Hypothetical Structure Length – 60 m Width – 24 m Top Down vs Bottom Up Total cost $4.0 M Total cost $4.7 M Less TIME taken
  5. 5. Rate of volume of earth to be excavated (20m) $129/m3 $99/m3 Rate of concrete to be used for roof slab (1.5m) $150/m3 $150/m3 Rebar (adopt 230 kg/m3) $1.46/kg $1.46/kg Area of formwork to be used NA $75/m2 Hypothetical Structure Length – 60 m Width – 24 m Top Down vs Bottom Up Total cost $4.0 M Total cost $4.7 M Less TIME taken
  6. 6. Reasons for higher cost of Top - Down • Limited construction openings for handling materials and machineries. • Limited headroom for excavators to operate. • Need more lightening and ventilation systems. • Even though there is no scaffolding materials used to prop the formwork to the soffit of the roof slab in Top – Down Method yet its price is high because of very high rate of the volume of earth to be excavated. NOTE – cost figure represent C929A and cannot be generalised
  7. 7. Tunnel Alignment
  8. 8. Expo Bound Bukit Panjang Bound C929A Station Box C929 C928 WEST Cut and Cover Tunnel Alignment
  9. 9. START END
  10. 10. EAST Cut and Cover Tunnel Alignment C927 Expo Bound Bukit Panjang Bound Station Box C928
  11. 11. START END
  12. 12. Key Position Selection
  13. 13. KEY position 7 to 11 are not used because • It is difficult to install as Connection Segments (B) and Standard Segments (A) are under compression. • It is the weakest link. Sequence of Key Position Selection for building Segments
  14. 14. Required Information • Straight portion of the Tunnel • Tunnel is moving UPWARD
  15. 15. L16 R2, R5, R14
  16. 16. SUSTAINABLE DEVELOPMENT
  17. 17. Choose efficient formwork Timber Formwork System Formwork Material Timber & Plywood Aluminium Durability 20 times 120 – 150 times Wastage Yes No Quality Workmanship dependent Good Labour Skilled Unskilled Cost $26/m2 $34/m2 Source – Guidebook for best environmental practices, LTA, Singapore
  18. 18. Environmentally Improved Materials • Using MILLED WASTE for temporary pathway instead of concrete. • Using factory prefabricated reinforcement because there is : 60% reduction in processing waste 30% increase in labour productivity • Good coverage of stockpile using Erosion Control Blanket either Natural material blanket or synthetic blanket. • Using Scrap bin for disposing welding rods, twisted steel wires, etc. for recycle.
  19. 19. Learning Outcomes
  20. 20. Challenges Encountered Bedok North Station (1) Water Canal Diversion Temporary Canal HDB D-WALL SBP In case of any failure, water will remain confine between D-Wall and SBP and station box remains unaffected
  21. 21. Bedok North Station Challenges Encountered (2) Water Ingress Stock pile Water squeeze out from underground into the station box due to additional surcharge because of stock pile
  22. 22. Kaki Bukit Station – Challenges Encountered Restriction in space • Top 2 metres from ground had scattered services lines that took an additional 9 months for its diversion and trench building • Bottom up might take less time but presence of HDB and factories on either side of the station made it safe to use top down construction method to limit the D - wall movement.
  23. 23. Why is there a discontinuity in the coupler position ?
  24. 24. Presence of WATER STOP
  25. 25. Plan View Elevation View Water Stop Stop End Couplers D - Wall
  26. 26. Why is there a rope hanging in a Slurry Storage Tank ?
  27. 27. Desander float marker Excavated area Slurry Storage tank marker float
  28. 28. Construction Market Activity Cycle Model Where WE stand ?
  29. 29. Peak Zone Mid Zone Trough Zone GROWTH DECLINE Apartment Industrial Building Offices, HotelCIVIL
  30. 30. agnes kamsiah CK SIMON KINSKI SELVAKUM AR MOD YOU GEN SHAWN Thank you

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