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IS 4651:2008 Part 3 is the Indian Standard (BIS) for loads for railway bridges: steel railway bridges. Code of practice for the planning and design of ports, harbours, and related marine structures. It spans multiple parts covering site considerations, earth pressures, loading (including berthing and mooring forces), general design, and layout requirements. (Note: Railway bridge loads are governed by IRS Bridge Rules, not IS 4651).
Specifies particular loading conditions and design considerations applicable to steel railway bridges.
Overview
Status
Current
Usage level
Specialized
Domain
Structural Engineering — Bridges and Bridge Engineering
! Always account for the added mass of water (Cm) when calculating berthing energy, as it significantly increases the total kinetic energy.
! Fender systems must be carefully selected to absorb the calculated berthing energy without exceeding the permissible reaction forces on the substructure.
! Ensure adequate concrete cover and use corrosion-resistant materials due to the highly aggressive marine environment.
BS EN 1991-2:2003CEN (European Committee for Standardization), Europe
HighCurrent
Eurocode 1: Actions on structures - Part 2: Traffic loads on bridges
Defines traffic loads and other actions for the design of road and railway bridges.
AREMA MRE, Chapter 8 & 15AREMA (American Railway Engineering and Maintenance-of-Way Association), USA
HighCurrent
Manual for Railway Engineering (Chapters on Concrete and Steel Structures)
Specifies design loads, including live load (Cooper E), impact, and longitudinal forces for railway structures.
AASHTO LRFD Bridge Design Specifications, 9th EditionAASHTO (American Association of State Highway and Transportation Officials), USA
MediumCurrent
AASHTO LRFD Bridge Design Specifications
Comprehensive bridge design code, with specific sections on railway live loads (Cooper E) and associated forces.
UIC Leaflet 776-1 RUIC (International Union of Railways), International
HighCurrent
Loads to be considered in the design of railway bridges
Provides internationally agreed-upon load models, forming the basis for many national standards including Eurocode.
Key Differences
≠The primary live load model in IS 4651 is the 'Revised Broad Gauge (RBG) Loading', which is based on specific Indian rolling stock. This contrasts with the abstract 'Load Model 71 (LM71)' in Eurocode and the historical 'Cooper E' loading in US standards (AREMA/AASHTO).
≠IS 4651 uses a 'Coefficient of Dynamic Augment' (CDA), a single formula-based impact factor dependent on span. Eurocode employs a more complex dynamic factor (Φ) that can account for track quality and resonance, while AREMA uses a different span-based formula.
≠Eurocode 1-2 provides highly detailed Fatigue Load Models (FLMs) to assess the cumulative damage over the design life. IS 4651 does not explicitly define separate fatigue load models, relying on the standard live loads for fatigue checks.
≠The definition and magnitude of longitudinal forces differ. IS 4651 specifies braking/traction forces as a percentage of live load or a force per unit length, while Eurocode 1-2 specifies characteristic line loads (e.g., 20 kN/m for braking) up to a maximum total force.
Key Similarities
≈All standards categorize loads similarly, including permanent loads (dead load), variable loads (train live load), dynamic effects, longitudinal forces, centrifugal forces, and environmental loads.
≈The fundamental principle for calculating centrifugal force on curved tracks is consistent across all standards, being a function of live load weight, design speed, and curve radius.
≈All codes specify loads for accidental scenarios, such as derailment, although the specific load values and application points vary.
≈The overall objective is the same: to provide a set of characteristic loads and actions that ensure the safety and serviceability of railway bridges under operational and environmental conditions.
Parameter Comparison
Parameter
IS Value
International
Source
Standard Vertical Live Load Model
Revised Broad Gauge (RBG) Loading: A defined train with specific axle loads and spacing.
Load Model 71 (LM71): Four 250 kN concentrated axle loads preceded and followed by a uniformly distributed load of 80 kN/m.
EN 1991-2:2003
Alternative US Live Load Model
25t Loading-2008 for heavier traffic.
Cooper E-80: A hypothetical locomotive with 80,000 lbs (356 kN) per axle followed by a uniform load of 8,000 lbs/ft (116.7 kN/m).
AREMA MRE
Dynamic Factor (Impact) for Steel Girder
Coefficient of Dynamic Augment (CDA) = 0.15 + 8 / (6 + L), where L is loaded length in meters.
Dynamic Factor (Φ₂) = 1.44 / sqrt(L_Φ) - 0.2 (for L_Φ between 1m and 20m) for carefully maintained track.
EN 1991-2:2003
Braking Force (Longitudinal)
10% of the weight of design train that can be placed on the span (for continuously welded rail).
A characteristic force of 20 kN/m, applied over the loaded length, with a maximum of 6000 kN.
EN 1991-2:2003
Traction Force (Longitudinal)
15.6 kN/m for spans up to 30m, then a total load of 468 kN.
A characteristic force of 25 kN/m, applied over the loaded length, with a maximum of 1000 kN.
EN 1991-2:2003
Derailment Load on Deck
Not explicitly quantified in IS 4651, which focuses on containment. Design is per 'Manual on design and construction of well and pile foundations'.
A vertical load of one bogie (e.g., 250 kN for LM71) applied anywhere on the deck over a specific area.
EN 1991-2:2003
Nosing Force (Lateral)
A single moving force of 100 kN acting horizontally at rail level.
A single concentrated force of 100 kN acting horizontally. Not combined with centrifugal force.
EN 1991-2:2003
⚠ Verify details from original standards before use
Key Values4
Quick Reference Values
approach velocity0.15 to 0.50 m/s depending on ship size and exposure
bollard pull100 kN to 1500 kN based on vessel displacement
live load general cargo25 to 50 kN/m2 on wharves
added mass coefficient Cm1.3 to 1.8 depending on under keel clearance
Key Formulas
E = (W * V^2 / 2g) * Cm * Ce * Cs * Cc — Berthing kinetic energy of vessel
Tables & Referenced Sections
Key Tables
Part 3: Table 2 - Approach velocity of ships for berthing
Part 5: Table 1 - Minimum approach channel widths
Key Clauses
Part 1: Clause 3 - Site Investigation
Part 1: Clause 5 - Meteorological and Oceanographic Data
Using the kinetic energy formula factoring in vessel displacement, approach velocity, and coefficients for added mass, eccentricity, softness, and berth configuration.
What is the typical live load for general cargo wharves?+
Typically 2.5 to 5.0 t/m2 (25 to 50 kN/m2) depending on cargo type and handling equipment.
What factors influence mooring forces?+
Wind and water current forces acting on the exposed profile of the vessel, which are then transmitted to the structure via mooring lines.