This is a Handbook cum Coffee Table Book on Bridging over River Bhagirathi (alias Ganges)- Concept to Completion by Rajesh Prasad, Executive Director, Rail Vikas Nigam Ltd (RVNL) depicting from the concept to completion of the Railway Bridge including cantilever launching of the open web girders with span size of 103 m.
5. To bridge the infrastructure deficit on Indian Railways, the
then Hon’ble Prime Minister, Bharat Ratna Shri Atal Bihari
Vajpayee announced National Rail Vikas Yojana (NRVY) on
15th August 2002 in his address from Red Fort. NRVY was
formally launched by Hon’ble PM on 26th December 2002.
To implement NRVY, RVNL was incorporated as a PSU on
24.01.2003; it is 100% owned by Ministry of Railways (MOR).
Bridgingthegap
Rail Vikas Nigam Limited 01
6. RVNL -Touching New Heights
Bridging over River Bhagirathi - Concept to completion02
7. Rail Vikas Nigam Limited(RVNL), a Miniratna
(category 1) Central Public Sector Enterprise (CPSE)
under the Ministry of Railways, was incorporated in the
year 2003 with the twin objectives of implementation
of projects relating to creation and augmentation of
capacity of rail infrastructure on a fast track basis and
raising of extra-budgetary resources. The highlights of
the performance of the Company are as under: -
• During 2017-18, RVNL commissioned 1178 km
of project length including 400 km of Doubling,
17 km of New Line and 605 km of Pure Railway
Electrification works and an additional 156 km of
RE works along with doubling/3rd/4thline projects.
• Since inception, RVNL has completed 231 km of
New Line, 2663 km of Doubling, 1676 km of Gauge
Conversion and 3262 km of Railway Electrification
i.e. a total of 7832 km of project length as on 31st
March 2018.
• The turnover of the Company reached a figure of
Rs. 5920 crore in 2016-17 as compared to Rs 4541
crore in 2015-16 and it has exceeded Rs 8050 crore
in 2017-18.
• With a perfect score of 100/100 along with other
7 other CPSEs amongst total 181 assessed, RVNL
has been rated “Excellent” for the year 2016-17,
seventh times in a row, by the Department of Public
Enterprises (DPE), Government of India.
• The Company has been ranked 1st amongst the
Railway CPSEs for the last three years continuously.
About RVNL
Rail Vikas Nigam Limited 03
8. Mission
To create state of the art rail transport infrastructure
to meet growing demand.
Vision
To emerge as the most efficient provider of rail
infrastructure with a sound financial base and global
construction practices for timely completion of
projects.
Objectives
• To undertake and execute successfully project
development, financing and implementation of
projects relating to Infrastructure especially to Rail
Infrastructure.
• To mobilize the required resources for project
implementation.
• Timely execution of projects with least cost
escalation.
• To maintain a cost effective organizational set up.
• To encourage public private participation in rail
related projects managed by RVNL.
• To be an infrastructure Project Execution Company
committed to sustainable development and
environment friendly construction practices of rail
related projects in the country.
• To acquire, purchase, license, concession or assign
rail infrastructure assets including contractual
rights and obligations with the approval of MOR
wherever required.
• To maintain highest standards of quality and safety
during construction.
Board of directors
S. C. Agnihotri
Chairman &
Managing Director
Gita Mishra
Director (Personnel)
Vijay Anand
Director (Projects)
Arun Kumar
Director (Operations)
Bridging over River Bhagirathi - Concept to completion04
11. Project Background
• Nabadwip Ghat station of Sealdah division has been planned to connect
Nabadwip Dham Station of Howrah division of Eastern Railway.
• The new BG Railway line from Nabadwip Ghat to existing Nabadwip Dham
Station runs mostly towards North-South, East-West and South-North direction
like “U” shape. The alignment passes through an area having agricultural land
and marshy land. Bhagirathi river is one of the most important river crossed by
the proposed alignment which basically originates from Ganga river and falls in
the ocean Bay of Bengal.
• There are total 24 nos of Bridges planned for the stretch out of which there exists
one important bridge, 10 nos of Major Bridges, 14 nos of Minor Bridges including
2 nos. of ROBs and 7 nos. RUBs. All bridges are designed with loading standard of
25T. The important Bridge Span (5 x 103.5 m + 2 x 30.5 m) is over Bhagirathi river.
• The said important Bridge Bhagirathi is located approximately 1.70 km down
stream of existing Gouranga Setu, a Road Bridge on the same River over SH – 8.
• Nabadwip is the birthplace and abode of the founder of Vaishnav Religion and
great social reformer “Shri Chaitanya Mahaprabhu”. Nabadwip in Nadia District,
West Bengal is a historic town situated on the bank of Bhagirathi River. Religious
followers from all over the world visit Nabadwip to feel essence of the sacred
place and also visit places like “Sonar Gouranga Temple”, “Mayapur Mandir” and
“ISKCON Temple complex”. Therefore this new line is going to be very vital and
important from religious point of view and also from the requirement of smooth
traffic operation in two divisions of Eastern Railway.
Rail Vikas Nigam Limited 07
12. Entire Project at a glance
Project Length 12.169 Km
Gradient
a) Ruling Gradient 1: 200
b) Maximum Length of Ruling
Gradient
700 m
c) Steepest Gradient in Yard 1 in 1200
Standard of Construction
a) Gauge 1676 mm
b) Rails 60Kg
c) Sleepers PSC, 1660 Nos/Km for Main Line
and 1540 Nos/Km for Loop Lines
and Sidings.
d) Points and Crossing 60Kg Rails, 1in12 Curved Switches
and CMS Crossing on PSC
Sleepers.
e) Maximum Speed 100 KmPh
Curves
a) Maximum Degree of
Curvature
3 (583.33 m Radius)
Bridges
a) Standard of Loading 25T of 2008
b) Total Nos of Bridges 25 Nos
(i) Important Bridges 01 Nos
(ii) Major Bridges 10 Nos
(iii) Minor Bridges 14 Nos
(iv) Total Water Way 702.2 m
(v) Longest Bridge 591.552 m
Road Crossing
a) Total No of ROB 2 Nos
b) Total No of RUB 7 Nos
Point and Crossings
1 in 12 11 Nos
RVNL-Bridgingthegapof
infrastructuredeficit..
Bridging over River Bhagirathi - Concept to completion08
13. SALIENT FEATURES OF
BHAGIRATHI BRIDGE
LENGTH 591.552M
LOADING 25 MT
SPAN (C/C of Pier) 1 X 33.276 + 5 X 105 + 1 X 33.276
SUPERSTRUCTURE Open Web Through Type Double Warren
Latticed Girder, Width – 5.5m, Height –
12.25m
BEARING Cylindrical bearings for 103.5m span Metallic
Roller & Knuckle type bearing for 30.5m span
PIER RCC Solid Circular Type - 4000 mm dia
ABUTMENT RCC Solid Wall Type – Thickness at base
3000mm
FOUNDATIONS Circular Well foundation
PIER WELL 11m diameter, Founding Level at RL (-)
23.70m
ABUTMENT WELL 13.5 m diameter, Founding Level RL (-)
26.60m for A2 and RL (-) 23.00m for A1
LEVEL OF RAIL RL (+) 24.016m as per GTS BM near Kalinagar
Station
FORMATION LEVEL RL (+) 23.278 m as per GTS BM near
Kalinagar Station
TRACK PARAMETERS 60kg Rail, Height – 172mm, Steel Channel
Sleeper – 150mm
TROLLY REFUGE Provided on each pier supported on
Superstructure Girder
SEISMIC
ATTACHMENTS
Seismic Reaction Block for Transverse seismic
and for Longitudinal Seismic Unseating
arrangement provided.
Rail Vikas Nigam Limited 09
14. TECHNICAL NOTE1.0 Recently, RVNL/Kolkata PIU has constructed a cable stayed bridge
over very busy yard, Barddhaman using Cantilever erection method without
affecting the train operation with the following features:
• LARSA 4D model and Wind tunnel test
• LUSAS model for Construction Stage Analysis and Geometry Control to
ensure safety during erection over electrified yard during execution
• Use of precast RCC slabs to avoid scaffolding for deck casting
• Composite structures for easier construction
• Monolithic Back Span
• Durable painting using epoxy based paint of AkzoNobel.
2.0 Another technical challenge was faced for construction of a Rail Bridge
over river Bhagirathi connecting Nabadwip Dham of Howrah Division and
Nabadwip Ghat of Sealdah Division of Eastern Railway. The proposed new line
is going to be a very important line for connecting two Divisions of Eastern
Railway running almost parallel. This will also serve the purpose of bypass and
in case of accidents. Nabadwip being the birth place of founder of Vaisnab
religion and a great social reformer, Shri Chaitanya Mahaprabhu and Mayapur
(ISKCON) being a landmark where millions of pilgrims/visitors come to this
place using various modes of transport will use this link in time to come.
3.0 After complete geo-technical investigation and the survey, the
General Arrangement Drawings were made and the same were in principle
approved by –
• Inland Waterway Authority of India(IWAI)
• Irrigation and Waterways Department, Govt. of West Bengal
• Kolkata Port Trust
4.0 Applicable Codes and Standards
Indian Railway Schedule of dimensions for Broad Gauge
IRS Bridge Rules (with latest A&C slips)
IRS Concrete Bridge Codes (with latest A&C slips)
IRS Steel Bridge Code
IRS Code of practice for the design of Substructures and
Foundation of Bridges(latest version)
IRS Manual on the design and construction of well and pile
foundations (1985) issued by RDSO, Lucknow
IRS RDSO/IITK Guidelines of Seismic design of Railway
Bridges
IRS Steel bridge code Appendix ‘G’ (Revised) for Fatigue
Assessment for Steel Bridges
IRC : SP13 Guideline for design of small Bridges & Culverts – for
Hydraulic Calculation
IRC : 5 General Features for Design of Road Bridges – for
Hydraulic Calculation
5.0 Loadings Considered
• Dead Load & Superimposed Dead Load
• Live Load – 25T loading of 2008 as per IRS Bridge Rules,
Appendix XXII along with Dynamic Augmentation
(CDA)
• Racking Load – As per IRS Bridge Rules
• Tractive or Braking Force – as per IRS Bridge Rules
• Wind Load – IRS Bridge Rules & IS:875(Part-III)
• Wind Speed – 50m/sec, Wind Pressure – 212 Kg/m2
for no Live Load condition and 150 Kg/m2 for loaded
condition as per IRS Bridge Rules
• Seismic Forces – As per RDSO / IITK Guidelines on
seismic design of Railway Bridges, Zone - III, PGA -
0.16g, Augmentation Factor – 1.5
6.0 Material Specification
Material specifications used for construction of the bridge
are –
• Steel Superstructure – E250, Grade – Bo, IS : 2062 – 2011
• RCC Concrete work – M35
• PCC Work – M25
• Reinforcement – Fe 500D as per IS: 1786 – 2008
7.0 The construction of the bridge is having following
special features:-
• Well Foundation
• Cutting Edge
• Well Curb
• Well Staining
• Caisson Floating
• Launching
7.1 Well Foundation: M/s. STUP Consultants was
engagedtoworkastheDesignConsultantandIIT/Roorkee
as Proof Consultant for the various designs undertaken
for the said project. Well foundation was considered
because of the kind of river and it was also decided to take
it down to the founding level through all kinds of sub-
strata, plugging the bottom, filling the inside of the well,
plugging the top and providing a well cap in accordance
with the design formulated and proof checked by IIT/
Roorkee.
by the Author*
* Rajesh Prasad, Executive Director RVNL
Bridging over River Bhagirathi - Concept to completion10
15. 7.2 Cutting Edge: The cutting edge was erected on
firm level ground. Temporary supports were provided and
erection of the assembly was maintained in true shape
and size. Fabrication was carried out in workshop located
near the worksite.
7.3 Well Curb: Steel framework for well curb was
fabricated strictly in conformity with the drawing and
design made,the proof checked by IIT/Roorkee. The outer
face of the curb was made vertical. Steel reinforcements
were as per the BBR. It was ensured that the framework
of the outer face of the curb was removed within 24 hrs.
after concreting and framework of the inner face used
was removed after 72 hrs. It was also ensured that the
concreting in the well curb is done in one go. This is as
per the design and recommendation of the DDC and the
proof consultant.
7.4 Well Staining: The staining built in the first lift
above the well curb was about 2M and subsequent lifts
were not more than diameter of the well or depth of the
well sunk below the adjoining bed level at any time. For
the purpose of stability, the first lift of staining was cast
only after the sinking of the curb partially for stability. It
was also ensured that the number of construction joints
remains less and the concreting layers were limited to
about 450mm restricting falling of concrete by not more
than 1.5M to avoid segregation.
7.5 Caisson Floating: Typical caisson floating adopted
is indicated in the following picture. Because of the
various ground condition there were different methods
adopted in various abutments and piers.
7.6 Launching Scheme: Because of the site condition and deep flowing
water of river Bhagirati, it was decided to use cantilever erection method for
girders using specially designed erection crane compatible to move and
erect the girders members.The crane with long boom and special kind of link
members with the pin arrangement was designed to add each member of
girder in place.The link member joining two spans can be seen from pictures.
Rail Vikas Nigam Limited 11
16. Different stages of the launching scheme has been elaborated in the
handbook.
S l .
No.
Particulars Detail Description
1. Launching Scheme Cantilever erection scheme for 103.5M span
through type truss girder
2. First Stage Span P1-P2(1st 103.5M span) erected
over trestle support and act as anchor
span(Approach Anchor span)
3. Second Stage After completion of anchor span, all the
trestle support underneath the span were
removedanderectioncranewasmadeready
to erect the balance 4 spans (103.5Mm) by
cantilever launching method.
4. Third Stage Span A1-P1 (1st 30.5M shore span) erected
over trestle support and P6-P7 (2nd 30.5M
shore span) erected by cantilever method.
For launching of both the shore spans of both end (30.5m), small crane was
erected and used successfully.
8.0 Safety at Worksite: For execution of such massive work over a
major river Bhagirathi, a lot of safety precautions were taken. Safety drill
was a regular feature. Workers using safety gears (PPE) was also a regular
feature, with floating tubes tied with the girder were something of special
kind. Round the clock medical van and the first aid medicine kits were made
available and the entire erection was completed as per
the time schedule. Safety audit used to be done on weekly
basis and weekly safety certificates were issued at site.
Typical sample of the safety audit report has been placed
9.0 Quality Assurance: Detailed method statements
were made for the quality assurance programme and
following quality procedure systems were followed:
• Document control
• Procurement control
• Material control
• Training of Personnel
• Non-conformance control
• Production control
• Setout control
The quality assurance plan submitted by the agency
was concurred by Detailed Design Consultant, approved
by RVNL and the Fabrication of steel structural was
approved by RDSO. RDSO vide their letter No. CBS/Insp/
WBG/E Rly dated 28.10.2013 approved the QAP stating
that QAP submitted by RVNL have been scrutinized and
found to be in order after some minor corrections which
were complied and followed at site for fabrication, trial
assembly and erection.
Bridging over River Bhagirathi - Concept to completion12
18. CLEARANCES
No Objection Certificate’for construction of the Railway Bridge over River Bhagirathi were obtained.
• Inland Waterway Authority of India (IWAI).
• Irrigation & Waterways Department; Government of West Bengal.
• Kolkata Port Trust(KOPT).
Kolkata Port Trust
15, Strand Road
Kolkata – 700001
Fax No 033-2230-4901
Telephone No. 2230-3451
Email : cpiedi@glasc101.vsnl.net.in
calport@vsnl.com
Administration Department
December 13, 2013
No. Admn/6454/RVNL/Nabadwip
The Chief Project Manager,
Barrackpore,
Kolkata Project Implementation Unit,
Kalighat Metro Railway Station Building,
(North-East Corner), First Floor,
41A, Rash Behari Avenue,
Kolkata – 700 026.
Reference your letter No. RVNL/KOL/KRIS-NBDP/28 dated 09.05.2012.
2. Your proposal for construction of a major rail bridge across river Bhagirathi from Nabadwip
Ghat to Nabadwip Dham with 576 mtrs. Span has been considered by the Board of Trustees and
permission has been accorded for the proposed construction on the following conditions :-
(i) KoPT will not take any responsibility including financial liabilities in regard to design and
safety aspect of the proposed bridge constructed under this scheme.
(ii) Any auxiliary structures if required, to be constructed in the river bank during the
construction period should be properly retrieved at the cost of RVNL after completion of the
proposed work.
(iii) During construction period, adequate safety and care should be taken so that no
excavated/surplus earth or any other constructional materials move into the river. All surplus earth are
to be levelled and dressed properly by RVNL.
(iv) Safety aspect during execution of the construction work should be followed strictly.
(v) The high and slope bank portion, both U/S and D/S of the proposed work site, should be
properly protected by revetment/pitching work etc.
(vi) A nominal one-time inspection charge of Rs. 1 lakh should be paid to KoPT before
commencing work.
Sir,
Sub : Clearance for construction of a major
bridge across river Bhagirathi under
National Waterway-I.
Bridging over River Bhagirathi - Concept to completion14
19. No. IWAI/PR/NW-1/Navi. Clearance/2012-13
The Chief Project Manager
Rail Vikash Nigam Limited (RVNL),
Kalighat Metro Railway Station Building,
41A, Rash Bihari, Avenue, Kolkata-700 026.
Ref : Your letter No. RVNL/KOL/KRIS-NABDP/dated. 18.05.2012 & 14.08.2012
Sir,
This has reference to your application and letters cited above requesting approval of navigational
clearance for construction of proposed rail bridge across river Bhagirathi at 1.70 Km. D/s of Sri
Gauranga Setu (Ch. 278.30 km.) of NW-I on State Highway No. 8, Nabadwip, District Krishnanagar.
(West Bengal).
In this context I am directed to convey that IWAI has no objection for proposed construction of
aforesaid bridge with horizontal clearance of 101 m and vertical clearance of 10.196 m above HFL as
indicated by you in the proposal.
IWAI will however, have the right to ask for removal/modification of structure in case more channel
clearance is required in future.
The construction of the bridge is to be carried out as per Annexure-II of the Office Memorandum of
this Authority vide No. IWAI/PLNW-3/9/98- Vol.-1, dated 27.08.2007 (Copy enclosed).
Encl : As above
Copy to:
The Director, IWAI, Kolkata for information and to monitor the clearance during implementation of the
project. This has reference to his various letters on this issue, the last one being IWAI/KOL/TECH/2011-
12/1348, dated 14.12.2012.
Tele. : Code – 95120 – 2544036, 2521684, 2522798, 2521724 Fax : 2544009, 2544041, 2543973, 2521764
Date : 20.12.2012
Rail Vikas Nigam Limited 15
20. GEO-TECHNICAL
INVESTIGATION
REPORT
Geotechnical/Soil investigation work considered
by sinking bore holes up to a required depth below
the existing ground level in all kind of soil formation
including collection of Undisturbed/ Disturbed Soil
samples and Standard Penetration Test.
Laboratory testing:
• Natural Moisture Content
• Sieve Analysis
• Hydrometer Analysis
• Liquid Limit & Plastic Limit
• Bulk & Dry Density
• Specific Gravity
• Tri-axial Shear Test (Un-Consolidated Un-Drained)
• Direct Shear test
• Consolidation Test
TYPICAL BORE LOG DETAILS
Soil Profile
Layer Description Depth SPT
I Loose / medium dense
yellowish grey / grey /
greyish yellow silty sand /
fine sand with traces of mica
16.50m 10-30
II Stiff to very stiff / hard
greyish brown / brownish
grey / grey silty clay with
varying percentage of sand
/ sandy silty clay
4.00m 23-40
III Medium dense / dense
greyish brown / yellow
/ yellowish grey / grey /
brownish yellow silty sand /
fine sand with traces of mica
23.0m 40-85
IV Hard grey / dark grey silty
clay (high silt content) with
occasional traces of sand
4.50m >100
V Dense / very dense grey
/ yellowish grey / greyish
yellow silty sand / medium /
fine sand
Beyond
48m
>100
Bridging over River Bhagirathi - Concept to completion16
22. Design Basis
(Prepared by DDC, vetted by IIT Roorkee)
Loading
• Earth Pressure – as per IRS Bridge Rules
• Dynamic Earth Pressure – as per RDSO/IITK guideline
for Seismic design
• Water Current force – as per IRS Bridge Rules
• Surcharge Pressure – as per IRS Bridge Rules
• Dynamic Surcharge Pressure – as per RDSO/ IITK
guideline
• Hydrodynamic Force – as per IRS Bridge Rules / RDSO/
IITK guideline
Load Combinations
For Superstructure:
• Combination I : DL+LL+CDA on LL+ Racking + Braking/
Tractive
• Combination II : Combination I + Wind Load
• Combination III : Combination I with 50% LL for
Longitudinal Seismic + Seismic Force
For Pier:
• Combination I : DL+LL+CDA on LL+ Racking + Braking/
Tractive + water Current Force
• Combination II : Combination I + Wind Load
• Combination III : Combination I with 50% LL for
Longitudinal Seismic + Seismic Force + Hydrodynamic
force
For Abutment:
• Combination I : DL + LL + CDA on LL + Racking
+ Braking/ Tractive + Earth pressure + Surcharge
pressure
• Combination II : Combination I + Wind Load
• Combination III : Combination I with 50% LL for
Longitudinal Seismic + Seismic force + Dynamic
increment on Earth pressure (Seismic effect on earth
pressure)
Bridging over River Bhagirathi - Concept to completion18
23. Sub-Structure
Sub-Structure :
1. Abutment
2. Pier
In both cases for abutment and pier, the basic methodology is
same except the sections of the structure. The foundation (well
foundation) part of both the abutment and pier are same except the
diameter of the well. The diameter of the abutment well foundation
is 13.50 meter where as the pier Well foundation is of 11.00 Metre.
After finishing up to well cap, the abutment reaches its formation
level through abutment wall, wing wall, abutment cap, inspection
platform, where as the pier has, pier shaft pedestal, pier shaft,
inspection platform etc. Detailed method statements were made
for:
a) Well Foundation
b) Sinking of Well
c) Precautions During Sinking
d) Safety During Sinking
e) Tilt & Shifts During Sinking
f) Bottom Plugging
g) Sand Filling
h) Top Plugging
Rail Vikas Nigam Limited 19
24. Well Foundation
Specifications for Well Foundation
This work consists of construction of well foundation, taking it down to the founding level through all kinds of sub-strata,
plugging the bottom, filling the inside of the well, plugging the top and providing a well cap in accordance with the details
shown on the drawing.
Cutting Edge
The parts of cutting edge were erected on firm level ground. Temporary supports were provided to facilitate erection
and maintaining the assembly in true shape. The fabrication was carried out in the shop or at site. Steel sections were not
heated and forced into shape. However,“V”cuts in some cases were made in the horizontal portion, uniformly throughout
the length, to facilitate cold bending. After bending, such“V”cuts were closed by welding. Joints in the lengths of structural
sections, unless otherwise specified were welded using single cover plate to ensure the requisite strength of the original
section.
The cutting edge was laid about 300 mm above prevalent level.
Well Curb
Bridging over River Bhagirathi - Concept to completion20
25. Assembling of Cutting Edge
General Arrangement & R. C. details of Well & Well Cap for Pier
Rail Vikas Nigam Limited 21
26. Well Curb
The well curb was either precast or cast-in-situ. Steel formwork for well curb was fabricated strictly in conformity with the drawings. The
outer face of the curb was made vertical. Steel reinforcements were assembled as per drawings. The bottom ends of vertical rods of staining
were fixed securely to the cutting edge with check nuts or by welds.
The formwork on outer face of curb were removed within 24 hours after concreting.The formwork on inner face was removed after 72 hours.
All concreting in the well curb was done in one continuous operation.
Well Staining
Staining built in the first lift above the well curb was not more than 2 metres and in subsequent lifts, it was ensured not to exceed the diameter
of the well or the depth of well sunk below the adjoining bed level at any time. For stability, the first lift of staining was cast only after sinking
the curb partially for stability. Concreting of staining was carried out in subsequent lifts of about 2 to 2.5 metres. Attempts were made to
minimise the number of construction joints.The concreting layers were limited to about 450 mm restricting the free fall of concrete not more
than 1.5 m.
Bridging over River Bhagirathi - Concept to completion22
28. METHODOLOGY -
ADOPTED
A1, P1 & P2 :
Normal procedures for sinking were followed for these
wells as these are on ground.
P3:
Done by creating Island with wooden ballah and
sand bags. Then normal procedures were followed
for sinking, crane was mounted on floating barge of
adequate capacity. Concreting was done by concrete
pump. Temporary pipe line was constructed on floating
gangway.
P4, P5 & P6:
These wells are on 5 to 7 meter deep water. Floating
caisson method adopted.
A2 (Now P-7):
Abutment -2 (now converted to P7) is partially on
ground and partially on water. Island was created with
sheet piling and sal ballah, two numbers of spurs were
also constructed at upstream to divert water current
(conversion of A2 to P-7 is for catering meandering
effect of river).
Concreting procedure :
Concreting for P3 to P5 was done by concrete pump and
pipe line taken on floating barges. A booster pump was
fixed near P-3 on barge. For A-2 and P-6 concreting done
by transit mixer from Nabadwip Dham end.
Bridging over River Bhagirathi - Concept to completion24
32. Fabrication
For fabrication work, a workshop near the worksite was setup with fully
Operational Tools & Machineries as per approved STR (Schedule for
Technical Requirement) by RDSO. The approved drawings were made
available for making QAP (Quality Assurance Plan), DODL (Drawing Office
Despatch List), WPSS (Welding Procedure Specifications Sheet), WPQR
(Welding Procedure Qualification Record) etc. Procurement of Raw Material
and Welding Consumable (Wire, Flux etc.) were be made as per approved
QAP and Drawings. Collecting of test Sample was always done jointly
(Client & Contractor) for 3rd Party Testing to ensure the required quality of
the procured raw Materials. After passing of the raw Material, Marking for
JIGS & Master was done at workshop as per approved drawings. A Layout
Platform was required for making the Layout of Camber and Nominal
dimension.TheJIGS,Master,CamberandNominalDimensionwerechecked
for approval by RDSO. After getting the approval of JIGS, Masters, Camber
and Nominal dimensions layout, the fabrication work of members of girder
through Marking, Cutting, Fit-up & Welding of RAW Materials (Steel Plates/
Rolled Section) were commenced. Welding was undertaken by approved
welders and as per WPSS. In house testing such as DP (Dye Penetration)
Test, Macro Etching Test etc. were done to ensure the Quality of Welding
and Eliminate Defects (Pin Holes, Cracks etc.). After that, Marking and
Drilling as per approved Drawings & JIGS, Shop Riveting and End Finishing
were done for finishing the member. After finishing the whole members
of girder, a Trial Assembly was done for checking the Camber and Nominal
dimensions of the span in all respect which was also checked and approved
by RDSO. After getting the approval of the Trial Assembly, the Members of
Girders used was made ready for Sand Blasting, Metalizing, Painting and
followed by Erection.
Bridging over River Bhagirathi - Concept to completion28
34. Quality
Quality Assurance:
For implementation of the projects, it was necessary that the
aspects related to quality should not at all be compromised. If
Quality assurance and control is not done properly, the work cannot
be done smoothly and the project would go into a vicious cycle and
it can result into delays.
A quality assurance programme was prepared along with a quality
control plan. The objective of quality assurance programme was
to ensure the construction activities are carried out in a systematic
manner and quality of construction work is in conformity with the
approved specifications, drawings, etc. It was based on the following
quality system procedure:
• Document control
• Procurement Control
• Material Control
• Training of Personnel
• Non-Conformance Control
• Production Control
• Setout control
QAP (Civil) :The Quality Assurance Plan (QAP) of Civil work was made
by the contractor, Vetted by the DDC and finally approved by RVNL.
QAP (Structural): The Quality Assurance Plan (QAP) for steel
fabrication was made by the contractor and approved by the RDSO.
Bridging over River Bhagirathi - Concept to completion30
37. Material Specification
• Steel Superstructure – E250, Grade – Bo, IS: 2062 - 2011
• RCC Concrete work – M35
• PCC Work – M25
• Reinforcement – Fe 500D as per IS:1786 – 1985
Quantity of major items in the projects
Particulars Unit Well
Foundations
Well Cap Pier Pier Cap
& Above
Abutments Superstructure
Concrete (M25) Cum 1542 - - - - -
Concrete (M35) Cum 17015 1656 1328 922 324 -
Well Cutting Edge MT 108.38 - - - - -
Cement Bag 157152 14179 11368 7892 2777 -
Admixture Litre 72483 6468 5187 3601 1266 -
Cassion MT 326 - - - - -
Sand Filling Cum 4960 - - - - -
TMT Steel MT 476 316 125 133 58 -
Structural Steel MT - - - - - 4258
RDSO Inspection team at Fabrication Site
Rail Vikas Nigam Limited 33
38. SUBSTRUCTURE DRAWING
Sl No. Drawing No. Description Rev.
1 9420/E/DD-001 General Arrangement Drawing 5
2 9420/E/DD-002 General Arrangement of Pier & Pier Well 2
3 9420/E/DD-003 General Arrangement of Abutment & Abutment Well 3
4 9420/E/DD-201 GA & RC detail of Pier & Pier Cap (Mkd. P2 to P5) 1
5 9420/E/DD-202 GA & RC detail of Pier & Pier Cap (Mkd. P1 & P6) 1
6 9420/E/DD-203 GA and RC detail of well & well cap for Pier 1
7 9420/E/DD-204 (Sheet 1 of 2) GA & RC detail of abutment, dirt wall & wing wall returning wall 2
8 9420/E/DD-204 (Sheet 2 of 2) GA & RC detail of Abutment, dirt wall & wing wall Returning Wall 2
9 9420/E/DD- 205 GA & RC detail of Well & Well Cap for Abutment 1
10 9420/E/DD-207 GA of caisson for Pier Well Mkd. P6 2
11 9420/E/DD-208 GA of caisson for Pier Well (Mkd. P3, P4 & P5) 2
12 9420/E/DD-209 GA of caisson for Pier Well (Mkd. P3 to P6) 0
SUPERSTRUCTURE DRAWING
Sl No. Drawing No. Description Rev.
1 9420/E/DD-004 GA of Open Web through type Welded Bridge Girder 2
2 9420/E/DD-005 Stress Sheet for Open Web Girder (Welded Through Type) 0
3 9420/E/DD-206 Load Data for Bearing 0
4 9420/E/DD-006 Camber Diagram for Open Web Girder (Welded Through Type) 0
5 9420/E/DD-007 Details of Top Chord Joint, Mkd. U1, U17 1
6 9420/E/DD-008 Details of Top Chord Joint, Mkd. U2, U3, U15 & U16 1
7 9420/E/DD-009 Details of Top Chord Joint, Mkd. U4, U5, U13 & U14 1
8 9420/E/DD-010 Details of Top Chord Joint, Mkd. U6, U7, U11 & U12 1
9 9420/E/DD-011 Details of Top Chord Joint, Mkd. U8, U9 & U10 1
10 9420/E/DD-012 Details of Bottom Chord Joint, Mkd. L0 & L18 1
11 9420/E/DD-013 Details of Bottom Chord Joint, Mkd. L1 & L17 1
12 9420/E/DD-014 Details of Bottom Chord Joint, Mkd. L2,L4, L14 & L16 1
13 9420/E/DD-015 Details of Bottom Chord Joint, Mkd. L3 & L15 1
14 9420/E/DD-016 Details of Bottom Chord Joint, Mkd. L5 & L13 1
15 9420/E/DD-017 Details of Bottom Chord Joint, Mkd. L6 & L8, L10 & L12 1
16 9420/E/DD-018 Details of Bottom Chord Joint, Mkd. L7 & L11 1
17 9420/E/DD-019 Details of Bottom Chord Joint, Mkd. L9 1
18 9420/E/DD-020 Details of Middle Joint, Mkd. M0, M1, M2, M16, M17 & M18 1
19 9420/E/DD-021 Details of Middle Joint, Mkd. M4, M6, M8, M10, M12 & M14 1
List of drawing
Bridging over River Bhagirathi - Concept to completion34
39. Erection Drawing
Sl. No. Drawing Title Drawing No. Sheet
1
Cantilever Erection Scheme for 103.5m span through type truss girder 2012-13-J-625 Sch-01
(Sheet 1 of 2)
2 (Sheet 2 of 2)
3
Details of Link Member Mkd LM-1, LM1x, LM2 & LM2x 2012-13-J-625 Sch-05
(Sheet 1 of 2)
4 (Sheet 2 of 2)
5 Details of Link Bracings 2012-13-J-625 Sch-06 (Sheet 1 of 1)
6 Details of Hanger Plate Mkd HP1 to HP16 2012-13-J-625 Sch-07 (Sheet 1 of 1)
7 Details of Hanger Device 2012-13-J-625 Sch-08 (Sheet 1 of 1)
8 Details of Buffer Slab, Bearing Slab & Link Pin 2012-13-J-625 Sch-09 (Sheet 1 of 1)
9 Details of Short Link 2012-13-J-625 Sch-10 (Sheet 1 of 1)
10 Details of Extension Piece Mkd EP1 & EP1x 2012-13-J-625 Sch-11 (Sheet 1 of 1)
Misc. Drawing
Sl. No. Drawing Title Drawing No. Sheet
1 ARRANGEMENT OF SHUTTERING FOR WELL CURB AT PIER LOCATION GPT/W-99/C-01 1 of 1
2 ISLAND FOR SETTING UP OF WELL CURB AT A-2 GPT/W-99/C-02 1 of 1
3 ARRANGEMENT OF SHUTTERING FOR WELL CURB AT ABUTMENT LOCATION GPT/W-99/C-03 1 of 1
4 DETAILS OF COFFERDAM FOR WELL CURB AT P-3 LOCATION GPT/W-99/C-04 1 of 1
5 ARRANGEMENT OF SHUTTERING FOR WELL STEINING AT PIER LOCATION GPT/W-99/C-05 1 of 1
6 ARRANGEMENT OF SHUTTERING FOR WELL STEINING AT ABUTMENT LOCATION GPT/W-99/C-06 1 of 1
7 DETAILS OF FALSE STEINING FOR PIER GPT/W-99/C-07 1 of 1
8 DETAILS OF STEEL CAISSON(WELL STEINING) FOR PIER WELL MARKED P4,P5 & P6 GPT/W-99/C-08 1 of 2
9 DETAILS OF SHUTTERING FOR PEDESTAL GPT/W-99/C-09 1 of 1
10 DETAILS OF SHUTTERING FOR PIER (IST LIFT) GPT/W-99/C-10 1 of 1
11 DETAILS OF FALSE STEINING FOR ABUTMENT WELLS GPT/W-99/C-11 1 of 1
12 DETAILS OF SHUTTERING FOR PIER (2ND LIFT) GPT/W-99/C-12 1 of 2
13 DETAILS OF SHUTTERING FOR PIER (3RD LIFT) GPT/W-99/C-12 2 of 2
14 SHUTTERING ARRANGEMENT FOR PIER CAP GPT/W-99/C-13
1 of 2
2 of 2
15 DETAILS OF SHUTTERING FOR ABUTMENT (1st lift) GPT/W-99/C-14 1 of 1
16 DETAILS OF SHUTTERING FOR ABUTMENT (2ND LIFT ) GPT/W-99/C-15 1 of 1
17 DETAILS OF SHUTTERING FOR WING WALL & ABUTMENT- 6th LIFT GPT/W-99/C-16
1 of 2
2 of 2
18 DETAILS OF SHUTTERING FOR WING WALL & ABUTMENT - 7th LIFT GPT/W-99/C-17 1 of 1
19 FOUNDATION OF TRIAL ASSEMBLY 103.5m SPAN GIRDER GPT/W-99/C-18
1 of 2
2 of 2
20 ERECTION OF 103.5m GIRDER- DETAILS OF TRESTLE GPT/W-99/C-19
1 of 2
2 of 2
21 SHUTTERING ARRANGEMENT FOR PIER CAP WITH CUP LOCK ARRANGEMENT GPT/W-99/C-20 1 of 1
22 DETAILS OF SHUTTERING FOR PIER WITH CUPLOCK SYSTEM GPT/W-99/C-21 1 of 1
23 DETAILS OF SHUTTERING FOR PIER MARKED P-7 WITH CUP LOCK SYSTEM GPT/W-99/C-22 1 of 1
Rail Vikas Nigam Limited 35
40. Safety
• ItwasensuredtocarryoutSafetyInstructionMeetings/ToolBoxMeetings
at Site every week for workers and site staff.
• First-Aid medicines and kits were always made available at each work
front. The list of the medicines were also available in the first-Aid boxes.
• Emergency vehicle was available during launching operation.
• Proper housekeeping practices were carried out in working area.
• Adequate personal protective equipments (PPE) were made available.
• No unauthorized entry in the protected zone.
• Staircase, railing, ladder etc used were regularly checked and properly
maintained.
• All electrical connections were carried out systemically and checked
frequently.
• Allthestandardmaterialplugs&socketswereusedforalltheconnections.
• Periodical checking for good condition & insulation of all portable tools
was ensured.
• Foot wear and safety Helmet with chin strip were made available.
• Use of safety goggles while welding/ gas cutting/ grinding etc.
• Use body guards. Gloves etc.
• Provision of functional fire extinguishers was ensured.
100% safe implementation without even a single minor injury/scratch to a worker.
Floating tubes
Bridging over River Bhagirathi - Concept to completion36
42. Launching
Sl No Particulars Detail Description
1 Launching scheme Cantilever erection scheme for 103.5m span through type truss girder.
2 First stage Span P1-P2 (1st 103.5mtr Span) erected over trestle support and acted as anchor span .
3 Second stage After completion of anchor span, all the trestle support underneath the span were removed. Then erection
crane used to erect the balance of 4 nos. of 103.5 m spans by Cantilever Launching method.
4 Third stage Span A1-P1 (1st 30.5m shore Span) erected over trestle support and P6-P7 (2nd 30.5mtr Span) erected by
Cantilever Method.
Another crane for cantilever
launching of end (smaller span)
Bridging over River Bhagirathi - Concept to completion38
43. Erection of 103.5 m span by Conventional &
Cantilever Method
1. Place Mobile Crane behind the Pier Mark P1.
2. Cross Girder at L0 location was erected.
3. Bottom Chords L0-L1 was erected.
4. Cross girder at L1 Location was erected.
5. Stringers between L0-L1 was erected.
6. Bottom Lateral Bracing of panel L0-L1 was erected.
7. Short Vertical L0-M0 was erected.
8. Diagonal M0-L1 was erected.
9. Vertical L1-U1 was erected.
10. Horizontal Tie M0-M1 was erected.
11. End Raker M0-U1 and Portal Bracing system was erected.
12. Extended feeding track up to L1.
Rail Vikas Nigam Limited 39
44. The sequence wise erection procedure for anchor span by the Mobile Crane is indicated here under
1. Cross Girder at L3 location was erected.
2. Bottom Chord L1-L3 was erected.
3. Cross Girder at L2 location was erected.
4. Bottom Lateral Bracing of Panel L1-L3 was erected.
5. Stringers between L1-L3 was erected.
6. Vertical L2-U2 was erected.
7. Diagonal L1-M2 was erected.
8. Diagonal U1-M2 was erected.
9. Top Chord U1-U3 was erected.
10. Portal at U1-U1’was erected.
11. Top Lateral at U2-U2’was erected.
12. Diagonal M2-L3 was erected.
13. Diagonal M2-U3 was erected.
14. Crane track laid over Top Chord U1-U3.
15. Cross Girder at L5 was erected.
16. Bottom Chord at L3-L5 was erected.
17. Cross Girder at L4 was erected.
18. Stringers L3-L5 was placed.
19. Bottom Lateral Bracings between L3-L5 was erected.
20. Vertical U4-L4 was erected.
21. Diagonal L3-M4 was erected.
22. Diagonal U3-U4 was erected.
23. Top Chord U3-U5 was erected.
24. Top Lateral at U3-U3’was erected.
25. Top Lateral at U4-U4’was erected.
26. Diagonal M4-L5 was erected.
27. Diagonal M4-U5 was erected.
28. Top Lateral Bracing between U1-U3 was erected.
29. Feeding Track laid up to L5.
30. Crane Track extended up to U5.
31. An Erection Crane (EC) of adequate capacity erected over
Top Chord with the help of Mobile Crane.
Bridging over River Bhagirathi - Concept to completion40
45. The sequence wise erection procedure for anchor span by the Erection Crane is indicated here under
1. Crane moves forward.
2. Cross Girder at L7 was erected.
3. Bottom Chord L5-L7 was erected.
4. Cross Girder at L6 was erected.
5. Bottom Lateral Bracing of Panel L5-L7’was erected.
6. Stringers in between L5-L7 was erected.
7. Feeding Track laid up to L7.
8. Vertical L6-U6 was erected.
9. Diagonal L5-M6 was erected.
10. Diagonal U5-M6 was erected.
11. Top Chord U5-U7 was erected.
12. Top Lateral U5-U5’was erected.
13. Top Lateral at U6-U6’was erected.
14. Diagonal M6-L7 was erected.
15. Diagonal M6-U7 was erected.
16. Top Lateral Bracing between Panel U5-U7 was erected.
Rail Vikas Nigam Limited 41
46. In the similar manner sequence-wise erection up to U17-L17 were done.
1. Crane moves up to U16.
2. Cross Girder at L18 was erected.
3. Bottom Chord L17-L18 was erected.
4. Bottom Lateral Bracing between L17-L18
Panels was erected.
5. Stringers L17-L18 was erected.
6. Feeding track laid up to L18.
7. Vertical L18-M18 was erected.
8. Diagonal L17-M18 was erected.
9. Horizontal Tie M17-M18 was erected.
10. End Raker U17-M18 was erected.
11. Temporary Portal at U17 was erected,
Portal Bracing was erected.
12. Extension gusset at U17-U17’was erected.
Bridging over River Bhagirathi - Concept to completion42
47. Erection Crane was placed between U15-U17 Panel of anchor span as shown
1. Hanging Device was connected from M18 of anchoe span.
2. Cross Girder at L0 was erected.
3. Bottom Chord L0-L1 fitted with Bearing Slab at L0 will be
erected and held by Hanging Device at L1.
4. End Vertical L0-M0 was erected.
5. Short Link M18-M0 was erected.
6. Cross Girder at L1 was erected.
7. Bottom Lateral Bracing of Panel L0-L1’was erected.
8. Diagonal M0-L1 was erected.
9. Vertical U1-L1 was erected.
10. Horizontal Strut at M0 was erected.
11. End Raker M0-U1 was erected.
12. Extension Piece at U1 was erected.
13. Link Prop at M18 of anchor Span was erected.
14. 1st Link Member and link bracing was erected.
15. Link Prop at M0 of cantilever Span was erected.
16. Link Pin at Extension Piece of cantilever span, 2nd Link
member and Link Bracing was erected.
17. Central Link Pin was erected.
18. Top Crane track was extended to facilitate forward
movement of Erection Crane.
19. Bottom feeding track was extended up to L1 after putting
stringers.
Rail Vikas Nigam Limited 43
48. 1. Hanging Device is was connected at U1.
2. Erection Crane moves was positioned between U17 to U1.
3. Bottom Chord L1-L3is was erected & held at L3 by Hanging
Device from U1.
4. Cross girder at L2 was erected.
5. Bottom Lateral Bracing of panel L1-L2’was erected.
6. Stringers between L1-L2 was erected.
7. Vertical U2-L2 was erected.
8. Diagonal L1-M2 was erected.
9. Diagonal U1-M2 was erected.
10. Top Chord U1-U3 was erected.
11. Top lateral bracing was erected.
12. Extend Crane Track up to U2.
13. Diagonal M2-L3 was erected.
14. Diagonal M2-U3 was erected.
15. Cross Girder at L3 was erected.
Bridging over River Bhagirathi - Concept to completion44
49. 1. Stringers between L2-L3 was erected.
2. Bottom Lateral Bracing L2-L3’was erected.
3. Crane Moves up to U2 after Placing Crane Track.
4. Feeding track laid up to L3.
5. Hanging Device connected at U3.
6. Bottom Chord L3-L5 was erected.
7. Cross Girder at L4 was erected.
8. Stringers between L3-L4 was erected.
9. Bottom Lateral Bracing L3-L4’was erected.
10. Feeding track laid up to L4.
11. Vertical L4-U4 was erected.
12. Diagonal L3-M4 was erected.
13. Diagonal U3-M4 was erected.
14. Top Chord U3-U5 was erected.
15. Top Lateral Bracing between panels U3-U5 was erected.
16. Diagonals M4-L5 was erected.
17. Diagonals M4-U5 was erected.
18. Cross girder at L5 was erected.
19. Bottom lateral bracing between panels L4-L5’was erected.
20. Stringers between L4-L5 was erected.
21. Feeding track laid up to L5.
Rail Vikas Nigam Limited 45
50. In this manner the erection crane moves forward erection truss members panel by panel sequence-wise to complete erecting up
to U11.
1. Stringers between L10-L11 was erected.
2. Bottom lateral bracing L10-L11’was erected.
3. Crane moves up to U10 to L11.
4. Feeding track laid up to L11.
5. Hanging Device fixed at U11.
6. Bottom Chord L11-L13 was erected.
7. Cross girder at L12 was erected.
8. Vertical L12-U12 was erected.
9. Diagonal L11-M12 was erected.
10. Diagonal U11-M12 was erected.
11. Top Chord U11-U13 was erected.
12. Top lateral bracing was erected.
13. Erection Crane Moves forward.
14. Diagonal M12-L13 was erected.
15. Diagonal M12-U13 was erected.
16. Stringers between L11-L12 was erected.
17. Bottom Lateral L11-L12’was erected.
18. Cross Girder at L13 was erected.
19. Bottom lateral Bracing between panel L12-L13’ was
erected.
20. Stringers between L12-L13 was erected.
21. Feeding track laid up to L13.
Bridging over River Bhagirathi - Concept to completion46
51. Bearing of cantilever span (fixed type) was placed at desired location on Pier. The sequence-wise erection procedure is indicated
hereunder.
1. Crane moves up to panel U16.
2. Diagonal M16-L17 was erected.
3. Diagonal M16-U17 was erected.
4. Bottom chord L17-L18 was erected.
5. Vertical L17-U17 was erected.
6. Temporary Strut between M16-M17 was erected.
7. Cross Girder L18 was erected.
Rail Vikas Nigam Limited 47
52. 1. End vertical member L18-M18 was erected.
2. Diagonal L17-M18 was erected.
3. Temporary Strut between M16-M17 removed.
4. Horizontal tie M17-M18 was erected.
5. End Raker U17-M18 was erected.
6. Temporary portal bracings erected at U17-U17’.
7. (For starting of cantilever erection for the next span)
Bridging over River Bhagirathi - Concept to completion48
53. Jacking at front end of cantilever span was done to release load from Link Pins. After release of load pins, Link members, Buffer Slab
etc were dismantled by the Erection Crane which would be taken at the rear end of cantilever span, to complete the isolation of
anchor span totality.
It was necessary to complete riveting (which closely follows erection) of all major members viz. Chord & Web members before using
the cantilever span as anchor span.
Cantilever span then acted on as anchor span for the span between piers P3 – P4
All the activities which were performed to start the cantilever erection of span between pier mkd.
Sequence was followed for P2 – P3 like:- free bearing for cantilever erection at L0; erection crane between U14-U16; extension GSTS,
at U17; bearing slab for anchor span; buffer slab supported over pier; hanging device from M18; link post from M18; 1st link member
with pin at U17; X-Girder at L0; Bottom chord with bearing slab at L0 held by hanging device from M18; short vertical between L0-
M0; short link between M18-M0; Diagonal M0-L1; X-Girder at L1; Vertical L1-U1; Horizontal strut M0-M1; Diagonal M0-U1;Extension
piece at U1 of cantilever span Temporary post at M0; 2nd Link member, Link pins Link bracings; Stringer Between L0-L1; Bottom
Lateral bracing Between panel L0-L1 Feeding track up to L1; Extension of crane track over Link.
Sequencing is very important…
Rail Vikas Nigam Limited 49
54. Cantilever erection
First span over ground with the support of trusses
Bridging over River Bhagirathi - Concept to completion50
58. Use ofToe Blocks in Cantilever Erection
For erection of OpenWebThroughType Girder over waterway, where
conditions do not permit the construction of false work, the most
practical & convenient method of erection is by Cantilever Method.
The cantilever span is erected by taking reaction from previously
erected span, the anchor span. In this method at the penultimate
stage the overturning moment due to weight of cantilever span and
erection crane placed at the cantilever end requires counter weight
to be placed on the anchor span to prevent overturning and ensure
stability.
Depending on the weight of the span the requirement of kentledge
becomes too huge and is almost impossible to place it on the anchor
span maintaining a clear gap for the feeding trolley. This may be
overcome by using of the weight of the span adjoining the anchor
span as kentledge. The transfer of this load of earlier span to the
anchor span is done by a mechanism of Toe Block. In fact Toe Block
is a type of Bracket connection system between the end of bottom
chord members of two consecutive erected spans.
Anchor span was erected on trestles at the shore. The erection of
balance spans was planned by cantilever method. Accordingly
erection scheme was prepared and approved by the client. As per
the approved scheme kentledge required is 170 MT with factor of
safety 1.5 against overturning.
This much weight could not be provided on the cross-girders not
only because of lack of space but it may exceed the permissible
stresses in the cross-girders. In view of this kentledge load was
provided partially on top chords also. For the subsequent spans
it was not practicable to provide kentledge on top chords due to
logistic problems and from safety consideration. Hence the scheme
of placing kentledge was discarded instead use of Toe Blocks was
contemplated. Detail design & drawings were prepared and got
approved.
TwoToeBlockswerefixedontheendofbottomchords.EachToeBlock
was designed to take load of 85 T. The brackets were composed of 2
built up channels fixed on outer faces of joints of bottom chord and
cross girders. Existing permanent bolts were removed and replaced
by drift one after another. Bolts for new connections were inserted
at drift locations after placing the brackets in position. HT Bolts
of grade 10.9 were used. On completion of erection the temporary
bolts were replaced by original bolts. The Toe Block connection is not
rigid instead a sliding arrangement is designed either with roller or
neoprene pads. In this case 100mm dia roller was used.
Hence, for bridge girders of long span requiring huge amount of
kentledge, it is advisable to go for the Toe Blocks as elaborated. This
method of cantilever erection usingToe Blocks not only save time in
erection process but also avoids any possible damage to permanent
members of the bridge girders while handling kentledge.
Bridging over River Bhagirathi - Concept to completion54
59. Adoption of Cylindrical bearings
There are 5 nos spans of 103.5 m span and 2 nos 31.926 m span. These 103.5 m spans are open web through type girders with bottom girders
made of channel section and other span of 31.926 m are through type girders made of built-up I section.
The circular issued by Railway Board for adoption of spherical bearings on 61 m spans and above, also covers adoption of cylindrical bearings,
as both the types of bearings are covered by the same national and international codes (including RDSO & MORTH codes) and follow the
same design concept and construction philosophy. In fact, the Bridge no. 20 of UBSRL project referred in Railway Board’s letter has been
constructed with cylindrical bearings which were supplied by M/s. Mageba. The same was adopted for Bhagirathi Bridge.
Rail Vikas Nigam Limited 55
60. COMPARISON
Sl No Roller-Rocker Bearings Cylindrical Bearings
1 Primitive design concept, not used in developed countries
anymore.
Modern design concept used throughout the world
2 Works on metal to metal line contact causing lot of wear and
tear and also stress concentration on the adjacent structure
Plane Contact between proper sliding interface for reduced
sliding friction and thereby no wear and tear. Also better stress
distribution.
3 Allows rotation about one axis Cylindrical bearing allow rotation about one axis
4 Induces eccentricity on the pier and substructure at the roller
end due to movement
No eccentricity on the substructure
5 Point of action of horizontal force is quite high resulting in
high flexural stress on the adjacent structure.
Point of action of horizontal force is quite low resulting in low
flexural stress on the adjacent structure
6 Working (i.e. moving/rotating) parts of the bearings are bare
steel surfaces which are highly prone to corrosion
Working (i.e. moving/rotating) parts are not bare steel surface but
materials like PTFE, Stainless Steel and Elastomer – not prone to
corrosion
7 Working parts are not protected, causing accumulation dirt/
debris on those surfaces resulting malfunctioning of the
bearings
By design working parts are well protected, preventing
contamination by dirt/debris for smooth functioning
8 Requires huge maintenance during service life Required almost no maintenance and provide long service life
(> 50 years)
9 Unnecessary/uneconomic use of steel Optimum use of materials, resulting in economic design
10 Quite expensive for large spans Comparatively less expensive especially where large movement
and rotational capability is required
Bridging over River Bhagirathi - Concept to completion56
63. SIMILAR LAUNCHING SCHEME FOLLOWED
FOR KARO BRIDGE (BR. NO. 206) OVER
KARO RIVER IN MAOIST AFFECTED AREA.
Inspection by GM and CAO/Con, S.E. Rly.
Rail Vikas Nigam Limited 59
64. ANCHOR SPAN ERECTEDWITH CRANE FOR
CANTILEVER LAUNCHING IN BR. GIRDER 206
Bridging over River Bhagirathi - Concept to completion60
66. Earlier cantilever launching with special kind of
Deck erection crane at Barddhaman was
successfully completed
Bridging over River Bhagirathi - Concept to completion62