Guideline es for the Design of Causeways and SubmeBridges bridge

IRC SP 82: Scope - Key Specifications & Tables

Scope (Clause 3):
Defines the extent of design and data collection for submersible bridge structures, including maps, plans, and hydrological data.

Key Tables & Specifications:

1. Survey Plan Extension Based on Catchment Area

2. Material Specifications (Clause 7.1, Table 7.16)

• Refer to Clause 7.1 for detailed material specs relevant to submersible structures.

3. Types of Superstructure & Span Ranges (Table 7.9)

4. Scour Depth for Foundation Design (Clause 6.2)

Hydrology and Flood Estimation - IRC SP 82 Key Points

1. Slope-Area Method (Manning's Formula)

• Velocity, ( V = \frac{1}{n} R^{2/3} S^{1/2} )

  • ( V ) = velocity (m/s)
  • ( n ) = rugosity coefficient (Table 4.3)
  • ( R = \frac{A}{P} ) = hydraulic mean depth (m)
  • ( S ) = slope (bed slope or corrected slope)

• Corrected slope: [ S = \frac{Z_1 - Z_2 + \frac{V_2^2 - V_1^2}{2g}}{L} ]

• Discharge: [ Q = A \times V ]

2. Rugosity Coefficient (n) - Table 4.3

3. Rational Method for Flood Discharge

[ Q = A \times I \times Z ]

• ( Q ) = max flood discharge (m³/s)
• ( A ) = catchment area (hectares)
• ( I ) = max rainfall intensity (cm/hr)
• ( Z = 0.056 \times f \times P \times t_c + 1 )
  • ( f ) = area correction factor
  • ( P ) = runoff coefficient (Table 4.4)
  • ( t_c ) = time of concentration (hours)

4. Runoff Coefficient ( P ) (Table 4.4)

| Catchment Type |

Hydraulic Design Considerations (IRC SP 82 - Clause 4 & related)

Key Formulas:

1. Superelevation (3.4.7): [ e = \frac{V^2}{225 R} ]

• (e) = Superelevation (m/m)
• (V) = Design speed (km/h)
• (R) = Radius of curve (m)

2. Empirical Flood Discharge (4.1.2.1): [ Q = C A^n ]

• (Q) = Max flood discharge (m³/s)
• (A) = Catchment area (km²)
• (C, n) = Empirical constants (region-specific)

3. Slope-Area Method (4.1.2.2): [ Q = A \times V ] [ V = \frac{1}{n} R^{2/3} S^{1/2} ]

• (A) = Wetted area (m²)
• (V) = Velocity (m/s)
• (n) = Manning’s roughness coefficient
• (R) = Hydraulic radius (m)
• (S) = Energy slope (bed slope)

4. Rational Method (4.1.2.3): [ Q = A \times I \times \phi ] [ \phi = 0.056 f P t + 1 ]

• (Q) = Max flood discharge (m³/s)
• (A) = Catchment area (hectares)
• (I) = Rainfall intensity (cm/hr)
• (f, P, t) = Catchment factors (area correction, permeability, time of concentration)

Tables:

Specifications:

• Design Discharge: Use highest

IRC SP 82: Structural Design of Causeways & Submersible Bridges

Key Definitions

• Causeway: Paved submersible structure with/without vents allowing flood passage.
• Submersible Bridge: Designed to be overtopped during floods.
• Design Flood Level (DFL): Highest flood level for design, typically 50 or 100-year return period.

Design Considerations

• Causeways and submersible bridges must withstand overtopping without structural damage.
• Use protected bed level (PBL) to prevent erosion.
• Provide adequate vent openings to reduce hydraulic pressure.

Typical Design Parameters

Basic Formula for Discharge through Vents (Orifices):

[ Q = C_d \cdot A \cdot \sqrt{2gH} ]

• (Q) = Discharge (m³/s)
• (C_d) = Discharge coefficient (~0.6-0.7)
• (A) = Area of vent opening (m²)
• (g) = Acceleration due to gravity (9.81 m/s²)
• (H) = Head difference (m)

Structural Design Tips

• Design for hydrostatic and hydrodynamic forces during submergence.
• Ensure foundation stability against scour and erosion.
• Use durable materials resistant to water and silt abrasion.

flowchart LR
    A[Design Flood Level] --> B[Causeway Elevation]
    B --> C{Vent Openings}
    C --> D[Size to Pass Flood Discharge]
    C --> E[Provide Bed Protection]
    B --> F[Structural Strength for Overtopping]
    F --> G[Hydrostatic & Hydrodynamic Loads]

Summary: IRC SP 82 emphasizes causeways and submersible bridges to be robust against overtopping, with adequate venting and erosion protection, designed for a specified

Key Specifications for Approach Roads & Protection Works (IRC SP 82)

1. Approach Roads (Clause 8.1)

• Gradient: Preferably ≤ 1 in 30; use vertical curves to avoid bumps (Fig. 8.1).
• Cutting vs Embankment: Cutting preferred to avoid washout; side slopes protected by stone revetment 1m above affluxed HFL.
• Safe Side Slopes (Submerged Condition):

• Side Drains: Lined drains on both sides, discharging ≥10 m from causeway edge.
• Pavement Composition:
  • 200 mm compacted moorum/gravel/crushed stone
  • 150 mm water bound macadam
  • 200 mm M30 cement concrete slab

2. Face/Cut-off Walls

• Should extend to safe depth to avoid scour.
• Profile trapezoidal to approximate natural hyperbolic flow (Fig. 8.4).
• Length: Level portion ≈ stream width at RTL + 2–5 m; total length ≈ stream width at OFL + 2–5 m.
• Batter on outside faces recommended.

3. Protection Works & Appurtenances (Clause 8.2 & 3.4)

• Footpath Width: ≥ 1.5 m each side.
• Safety Kerbs: ≥ 600 mm width.
• Approach Roadway Width (Table 3.3):

Bed Protection & Scour Control - IRC SP 82 Key Points

1. Components of Bed Protection (Clause 6.4):

• Upstream flexible apron
• Upstream cut-off wall
• Rigid flooring

2. Design Specifications for Floor Protection (Clause 6.4.2):

• Max post-construction velocity: 2 m/s
• Max discharge intensity: 3 m³/s/m (except for raft foundations)
• Flooring top level: 300 mm below lowest bed level
• Flooring thickness:
  • Standard:
    • 150 mm stone/bricks on edge in 1:3 cement mortar
    • Over 300 mm M15 concrete
    • Over 150 mm M10 concrete
  • For abrasive streams (velocity > 4 m/s):
    • 450 mm M20 concrete over 150 mm M15 concrete
• Joint spacing: ~20 m

3. Maximum Depth of Scour (Clause 6.2):

4. Scour Depth for Floor Protection (Clause 6.2.2):

IRC SP 82: Materials and Soil Investigation - Key Formulas & Tables

1. Material Specifications (Clause 7.1, Table 7.16)

• Refer to Table 7.16 for detailed material specs (not fully provided here).
• Essential to collect soil and material properties for design.

2. Survey Plan Scale Based on Catchment Area (Clause 7.1)

3. Scour Depth Estimation (Clause 6.2, Table 6.2)

4. Scour Factor for Clayey Soils (K) (Clause 6.1.7)

[ K = F(1 + V_c) ]

• (c): cohesion (kg/cm²)
• (V_c): velocity factor
• (F) depends on soil friction angle (\phi):

Safety Measures and Signage — IRC SP 82 Key Points

1. Footpath & Safety Kerbs (Clause 1.5):

• Footpath width ≥ 1.5 m each side.
• Discontinuous safety kerbs width ≥ 600 mm.
• Overall width between outer faces of kerbs or guideposts should align with roadway width (Table 3.3).

2. Approach Road Geometry (Clause 3.4.3):

• Minimum straight approach length: 30 m for 35 km/h design speed.
• Avoid horizontal curves within 100 m of submersible structure.
• Minimum curve radius:
  • Plain/Rolling terrain: ≥ 60 m
  • Hilly terrain: ≥ 30 m

3. Design Speed (Clause 3.4.4):

• Informatory boards to show speed limits:
  • Plain/Rolling terrain: 35 km/h
  • Mountainous terrain: 20 km/h

4. Roadway Width (Table 3.3):

5. Warning Signage (Clause 8.10):

• Two advance warning signs on each approach:
  • At 200 m: "Slow Down. Submersible Structure 200 m Ahead Speed Limit 15 kmph"
  • At 50 m: "Dead Slow Submersible Structure 50 m Ahead"
  • Additional: "Do not Cross when Flood Water Overtops the Carriageway"
• Rumble strips at 30 m ahead of submersible bridge (IRC:99).

Summary Diagram of Signage Placement

flowchart

IRC SP 82 — Load and Stress Analysis: Key Formulas & Specifications

Load Analysis

• Water Current Forces on Superstructure:
  • Drag Force and Lift Force depend on shape and velocity.
  • Velocity variation with depth:
    [ U^2 = 2 V^2 \frac{X}{H} ]
    where:
    • (U) = velocity at depth (X) from deepest scour
    • (V) = maximum mean velocity
    • (H) = total depth of flow
  • Drag and lift coefficients ((C_d), (C_l)) are shape-dependent; use hydraulic model studies or approximate methods.

Material Specifications (Table 7.16)

Bearing Placement (Clause 1.5)

• Concrete surface variation ≤ 1.5 mm for elastomeric pads.
• Bearings must be horizontal using tapered sole plates or RCC pedestals.
• Avoid placing different sized bearings adjacent or multiple bearings in line.

Expansion Joints (Clause 7.14)

• Movements ≤ 6 mm: no joint needed; use open joint with edge protection.
• Movements ≤ 10 mm: filler joints with 2 mm corrugated copper plate + fiber board + pre-moulded filler.
• Movements ≤ 40 mm: compression seal joints with galvanized steel nosing + elastomeric sealer.

flowchart TD
    A[Water Flow Velocity (V)] --> B[Velocity at depth (U)]
    B --> C[Drag Force (F_d) & Lift Force (F_l)]
    C --> D[Stress on Superstructure]
    D --> E[Foundation Load]

Summary: Use velocity-depth relation for water forces; adhere to concrete and bearing specs; design expansion joints per movement range and IRC:SP:69.

IRC SP 82: Construction & Maintenance Guidelines - Key Points

1. Design Data Collection & Presentation (Clause 7.1, Appendix 7.1)

• Maps & Plans:
  • Index map at 1:50,000 scale showing:
    • North line, project location, district/state
    • Possible submersible structure sites
    • Road network, nearby towns, landmarks
• Survey Plan Extension Based on Catchment Area:

* Whichever is greater.

2. General Construction & Maintenance Notes

• Use site-specific hydrology and topography data.
• Regular inspection for scour and foundation stability.
• Maintain approaches and protection works as per Clause 130.
• Follow material specs in Clause 7.16 for durability.

flowchart LR
    A[Start: Project Planning] --> B[Collect Hydrology & Topography Data]
    B --> C[Prepare Maps & Survey Plans]
    C --> D[Design Causeways/Submersible Bridges]
    D --> E[Construction & Material Selection]
    E --> F[Maintenance & Inspection]
    F --> G[Repair & Protection Work]

Summary:
Accurate mapping and data collection scaled to catchment size are critical. Follow IRC SP 82 guidelines for survey extent, design, and maintenance to ensure safe, durable submersible bridge construction.

IRC SP 82: References and Related Standards Summary

Key IRC & IS Codes Referenced:

Material Specifications (Table 7.2 excerpt):

Survey Plan Scale Based on Catchment Area:

Important Notes:

• Expansion joints per IRC:SP:69; no joint needed for movement ≤6 mm.
• Bearings installation details for elastomeric and metallic types.
• Warning