Construction Plan for Road Over Bridge (ROB)
This detailed construction plan outlines the key phases and steps for the construction of a road
over bridge (ROB) with a pile foundation, circular abutment shaft, and a single 36-meter steel plate
girder, as per the RDSO standard.
1. Preliminary Design and Survey:
• Site Survey:
Conduct a detailed survey of the project site to evaluate the existing topography, soil
conditions, and any potential obstacles (utilities, nearby structures, traffic flow, etc.).
• Geotechnical Investigation:
Perform a soil investigation to determine the load-bearing capacity and type of
foundation required (pile foundation in this case).
• Design Parameters:
o Bridge Type: Road Over Bridge (ROB)
o Girder Type: Single 36m steel plate girder as per RDSO standard
o Foundation Type: Pile foundation
o Abutment Type: Circular shaft abutments
o Traffic Load: Design load and live load as per Indian Road Congress (IRC)
guidelines
2. Preparation of Site and Mobilization:
• Clearing and Excavation:
Clear the site of vegetation, debris, and any obstructions. Excavate the area for the
foundation and abutment shafts.
• Traffic Diversion Plan:
Implement temporary traffic diversions or road closures, as required, for safety during
construction.
• Mobilization of Equipment:
Mobilize necessary construction machinery such as pile rigs, cranes, excavators, batching
plants, etc.
3. Pile Foundation Construction:
• Pile Design:
Based on the geotechnical investigation, determine the number, size, and depth of piles.
Typically, concrete piles or steel piles are used depending on the soil conditions.
• Pile Drilling and Installation:
o Drilling: Drill holes at designated pile locations using rotary or percussion
drilling methods.
o Pile Placement: Insert steel or concrete reinforcement cages into the drilled
holes and pour high-strength concrete.
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o Pile Driving (if necessary): In hard soils, steel piles may need to be driven into
the ground with a pile-driving hammer.
• Pile Load Testing:
Perform a load test to verify the pile’s load-carrying capacity and ensure it meets the
design specifications.
• Pile Cap Construction:
Once the piles are set, construct the pile cap using reinforced concrete to transfer loads
from the bridge deck to the piles.
4. Abutment Shaft Construction:
• Formwork and Reinforcement:
o Construct formwork for the circular shaft of the abutment.
o Place reinforcement bars according to the design specifications for the abutment
shaft.
• Concrete Pouring:
Pour high-strength concrete into the formwork in stages, ensuring proper compaction
and curing.
• Curing:
Allow the concrete to cure properly for the required duration to achieve the design
strength.
• Superstructure Integration:
Once the circular shaft abutments are cured, integrate them with the superstructure by
ensuring proper alignment and leveling.
5. Superstructure Construction (Steel Girder Installation):
• Preparation of the Steel Girder:
o Fabricate the steel plate girder according to RDSO standards, ensuring proper
welding and bolting techniques are followed.
o Perform quality checks, including non-destructive testing (NDT), for the steel
girder’s integrity.
• Transport and Positioning of Girder:
o Transport the fabricated steel plate girder to the site using cranes or other heavy-
duty equipment.
o Carefully position the girder on the pre-constructed circular abutments using
cranes.
• Girder Alignment:
Ensure the steel girder is properly aligned and level as per design specifications. The
girder must rest securely on the bearing pads of the circular abutment shafts.
• Connection to the Substructure:
Weld or bolt the girder securely to the abutment shaft, following the design
specifications. Use high-strength bolts and quality welding to ensure structural integrity.
6. Deck Construction:
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• Deck Slab Design:
Design the road deck slab for the appropriate load-carrying capacity based on IRC and
other applicable guidelines. It should include provisions for expansion, drainage, and
traffic load distribution.
• Formwork for Deck Slab:
Construct formwork for the bridge deck slab, ensuring it is level and secured.
• Deck Reinforcement and Concrete Pouring:
Place reinforcement according to design specifications and pour concrete for the deck
slab.
• Curing and Setting:
Allow the deck slab to cure for the required time to reach its design strength.
• Expansion Joints and Bearings:
Install expansion joints and bearings as required to accommodate thermal expansion and
contraction of the bridge structure.
7. Roadway and Drainage Work:
• Road Surface Construction:
o Construct the road surface over the deck slab, using materials as per the design,
such as asphalt or concrete.
o Ensure that the road surface is smooth and level.
• Drainage System:
o Install proper drainage systems, such as side drains, culverts, and catch basins, to
prevent water accumulation on the bridge.
o Ensure the drainage system is connected to the existing drainage infrastructure.
• Traffic Barriers and Railings:
o Install appropriate traffic barriers, guardrails, and safety railings to ensure the
safety of vehicles and pedestrians.
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TENTATIVE TIMELINE FOR CONSTRUCTION PHASE (~12-15 months)
A. Foundation Work (Pile Foundation) - 3 months
• Mobilization & Site Preparation (2 weeks)
o Temporary site offices, material storage, utilities
• Pile Boring & Installation (6-8 weeks)
o 1200mm dia. piles, depth ~25-30m depending on soil strata
o Reinforcement cage lowering, concreting using tremie method
• Pile Cap Construction (4 weeks)
o Excavation, formwork, reinforcement & concreting
B. Substructure (Circular Pier) - 2 months
• Pier Shaft Construction (4 weeks)
o Formwork & reinforcement placement
o Concrete pouring in lifts (3-4m per lift)
Pier Cap Casting (4 weeks)
o Shuttering, reinforcement & casting
C. Superstructure (Steel Span & RCC Girder) - 6 months
• Steel Girder Fabrication (Parallel Activity - 3-4 months)
o Shop fabrication, welding, NDT testing, painting
• Erection of Steel Girder (1.5 months)
o Transport, lifting & alignment using cranes
o Bolting/welding connections, final adjustments
• RCC Approach Span (Girder & Slab) (2 months)
o Girder casting, lifting & placement
o Deck slab shuttering, reinforcement & concreting
D. Deck Work & Finishing - 3 months
• Expansion Joints, Crash Barriers & Drainage (4 weeks)
• Asphalt/PCC Deck Wearing Coat (4 weeks)
• Road Markings, Lighting & Final Finishing (4 weeks)
