1. Presented by-
Pravin Kolhe,
MTech, Transportation System Engineering,
Department of Civil Engineering,
IIT Kanpur.

2. Overview of presentation
 Introduction
 Constraints during construction
 Planning for project
 Materials
 Techniques for Urban Transportation Structure
 Superstructure
 Substructure
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3. 1. Introduction
 Urban transportation infrastructure involves large
scale construction
 There are various constraints.
 Need of innovative techniques for timely completion.
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4. 2. Constraints during construction
 Space constraint
 Time constraint
 Utilities
 Environment
 Aesthetics
 Safety
 Economy
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5. 2.1 Space constraint
 Historical Places
 Existing structures
 Minimum disturbance
to traffic
Photo.1. Space constraint
Photo: http://www.civil.skanska.com/skanska/templates/page.asp?id=3359
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6. 2.2 Time constraint
 Construction of new infrastructure is normally taken up when
existing infrastructure is not sufficient to fulfill the demand.
 Urgent need to start and complete the construction
 During the construction, the existing infrastructure is strained
further.
 So, timely completion of the project is important.
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7. 2.3 Utilities
 Infrastructure normally passes through densely populated
area.
 So, there are some utilities as
 Water mains (Underground)
 Sewer lines (Underground)
 Telephone lines (underground or overhead)
 Power supply lines. (overhead)
 These utilities should be diverted, which is time consuming
and costly affair.
 Many times, the utilities are not known till the starting of
work.
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8. 2.4 Environment
 Air and noise pollution
 Due to slow moving vehicular traffic
 Due to construction activity
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9. 2.5 Aesthetics
Photo 2. Aesthetics of urban transportation infrastructure
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10. 2.6 Safety
 Accidents causes loss of
 Life
 Property
 Environment
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11. 3 Materials
 Preferred materials-
 Bricks
 Stones
 Timber
 Metals
 Concrete
 Composite
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12. 3.1 Bricks
•For small spans
•Light Loads
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13. 3.2 Stones
•Old construction
material
•For small spans
•Time consuming
•Light load
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14. 3.3 Timber
•Temporary Bridges
•Less span and less load
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15. 3.4 Metal
•Speedy
construction
•Large span
•Heavy loads
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16. 3.5 Concrete
•Precast
•Pre-stressed
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17. 3.6 Composite
Use of metal +
Concrete
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18. 4. Techniques for Construction
 Elevated structures are divided it to-
 Superstructure
 Substructure
Fig. 3. Components of elevated structures
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19. 4.1 Techniques for Superstructure
 Techniques-
 Span-by-span construction with precast girder.
 Precast post-tensioned segmental technique
 Continuous units on ground supported staging
 Central span by Cantilevering technique
 Balanced cantilevering technique
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20. 4.1.1 Span-by-span construction
with precast girders
 Most economical
 Prestressed girders are lifted
from casting yard and
transported to site on
trailers
 At site they are lifted and
placed on pier cap by
cranes.
 Deck slab is then casted
over these girders.
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21. 4.1.2 Precast post tensioned
segmental technique
 Simply supported post-tensioned units of 2~3 m with
epoxy bonded joints.
 For standardization of segments, cable profile is made
horizontal in the middle span.
Fig.5. Construction by Precast post-tensioned segmental technique
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22. 4.1.3 Continuous units on ground
supported staging
 At crossing, central span is more.
 So prestressed continuous units becomes obligatory.
 In such case, central unit can be casted by staging by
diverting traffic
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23. a) End spans are casted on staging
b) Traffic diverted and central span is casted on staging
c) Open to traffic.
Fig 7. Construction of continuous unit on ground supported staging

24. 4.1.4 Central span by cantilevering
technique
 End spans are casted on staging
 Central span is casted by cantilevering.
 When two cantilever meet, the stitch segment is
casted.
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25. a) End spans are casted on staging
b) Cantilevering construction started from ends
c) Cantilevering construction completed from both ends.
Fig 8. Construction of central span by cantilevering
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26. d) Stitch segment is casted
e) Construction completed
Fig 9. Construction of central span by cantilevering
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27. 4.1.5 Balanced cantilevering
technique
 Only end portion of end span is casted on staging
 Remaining end span and central span is casted by
balanced cantilevering.
 When two cantilever meet, the stitch segment is
casted.
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28. a) End portion of end spans are casted on staging
b) Cantilevering construction started from ends in both directions
c) Cantilevering construction completed from both ends.
Fig 10. Construction by balanced cantilevering
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29. d) Ground supported staging at end spans
e) Stitch segment is casted
f) Construction completed
Fig 11. Construction by balanced cantilevering
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30. Fig. 12. Construction by balanced cantilevering
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31. 4.2 Techniques for Substructure
 Techniques-
 Self supporting cutting.
 Sheet piles
 Diaphragm wall
 Single cast-in-situ bored pile.
 Driven casted pile
 Group of piles.
 Well foundation
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32. 4.2.1 Self supporting cutting
 For shallow
depth and hard
soil, soil cutting
is possible at self
supporting
slopes.
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33. 5.2.2 Using sheet pile
 For higher depth
&/or soft soil
sheet pile are
preferred.
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34. 4.2.3 Using diaphragm wall
 For deep
cutting, diaphra
gm wall is most
useful
 These are
installed prior to
taking up the
excavation work.
 Generally, it is
part of final
structure
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35. 4.2.4 Cast-in-situ bored pile
 150 - 600mm dia to 20m
deep
 As a rotary auger causes
minimal vibration it is
ideal for use next to
buildings or underground
services without
destabilization.
 Dewatering techniques
can be used if water is
present. Fig 13. Cast-in-situ bored pile
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36. 4.2.5 Driven casted pile
 150mm - 600mm to 20m
deep
 Used on soft soils overlay.
 Permanently steel cased
piles are driven with an
internal drop hammer.
 Suitable reinforcement is
then added and the casing
filled with concrete. Fig 14. Driven casted pile
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37. 4.2.6 Group of piles
 Most of pile foundations
consists not of a single
pile, but of a group of
piles, which act in the
double role of reinforcing
the soil, and also of carrying
the applied load down to
deeper, stronger soil strata.
Fig 15. Group of piles
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38. 4.2.7 Well foundation.
 Used under very heavy
loads to be carried by soft
soil.
Fig 16. Well foundation
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39. Thank you
(c) Pravin Kolhe, 2006
http://www.pravinkolhe.com/