Grameen Sampark (December 2015) Hindi Version

IS Code MORD 29: Introduction & Scope — Key Points

Suspension Bridge (Clause 1.4)

• Walkway hangs on vertical suspenders from main cables stretched between towers on riverbanks.
• Cables anchored to rocky walls or masonry blocks.
• Walkway is cambered upwards.
• Requires higher expertise and is costlier than suspended bridges.

Suspended Bridge

• Built without towers.
• Walkway hangs on suspenders attached to main cables.
• Foundations must be at a high elevation to maintain freeboard.
• Simpler and cheaper than suspension bridges.
• Longest span: 350 m (Bunwajor Ghat li over Sunkoshi River).

General Specifications

Typical Design Considerations

• Camber: Upward curvature to reduce sag.
• Freeboard: Clearance above water level.
• Anchorage strength: Must resist cable tension.
• Load factors: Walking load, wind, seismic forces.

Formula for Cable Sag (Parabolic Approximation)

[ y = \frac{w x^2}{2 T_0} ]

• ( y ): sag at distance ( x )
• ( w ): uniform load per unit length
• ( T_0 ): horizontal component of cable tension

graph TB
    A[Main Cable] -->|Vertical Suspenders| B[Walkway]
    A -->|Anchored to| C[Rocky Wall / Masonry Block]
    A -->|Stretched between| D[Towers]

Summary:
Suspension bridges use towers and anchored cables; suspended bridges omit towers but need high foundations. Suspension bridges cost more but allow longer spans. Design focuses on cable tension, anchorage, camber, and freeboard.

Types of Trail Bridges (per MORD 29)

1. Suspension Bridge

• Structure: Walkway hangs on vertical suspenders attached to main cables.
• Support: Main cables stretched between towers on opposite banks.
• Anchorage: Cables anchored to rocky walls or masonry blocks.
• Walkway: Usually cambered upwards.
• Cost & Expertise: Requires higher expertise and is costlier.
• Example: Khenlya Ghet Bridge, Baglung.

2. Suspended Bridge

• Structure: Walkway hangs on suspenders attached to main cables, no towers.
• Foundations: Must be placed high enough to maintain freeboard.
• Cost & Construction: Simpler and cheaper than suspension bridges.
• Longest Span: 350 m at Bunwajor Ghatli, Khotang District.

Key Specifications

Design Considerations

• Cambering of walkway in suspension bridges to improve clearance.
• Freeboard requirement to avoid flooding in suspended bridges.
• Foundation height critical for suspended bridges due to lack of towers.

graph LR
    A[Main Cable] -->|Vertical Suspenders| B[Walkway]
    A -->|Anchored| C[Rocky Wall/Masonry]
    D[Tower] --> A
    style D fill:#f9f,stroke:#333,stroke-width:2px

This diagram shows a suspension bridge with towers supporting main cables and vertical suspenders holding the walkway.

For detailed design, refer to Long-Span Trail Bridge Manual (Volume A) and Short-Span Trail Bridge Handbook (Volumes I & II) as per MORD guidelines.

Design Considerations for Suspension Bridges (IS Code MORD 29)

Key Points from Clause 1.4:

• Main cables are stretched between towers on opposite banks.
• Vertical suspenders hang the walkway from main cables.
• Walkway is cambered upwards for clearance.
• Cables are anchored to rocky walls or masonry blocks.
• Requires high expertise and cost compared to suspended bridges.
• Towers are essential; suspended bridges lack towers and are simpler/cheaper.

Essential Formulas & Specifications

Typical Design Parameters

• Span Length: Varies, e.g., Khenlya Ghet bridge.
• Walkway Width: Usually 1.2 - 1.5 m for pedestrian trails.
• Freeboard: Ensure clearance above high water level.
• Cable Diameter: Based on load and safety factors (refer IS 14268 for wire ropes).

Summary Diagram of Suspension Bridge Components

graph LR
A[Tower] -- Main Cable --> B[Anchor Block]
A -- Vertical Suspenders --> C[Walkway]
B -- Cable Tension --> A
C -- Load --> A

For detailed design, refer to Long-Span Trail Bridge Standard Technical Manual Volume A and IS 14268 for wire ropes.

Design Considerations for Suspended Bridges (per MORD 29 & LSTB Manual):

• Bridge Type: Suspended bridges have no towers; the walkway hangs on suspenders attached to main cables anchored at high foundation points on both banks.

• Span: Longest suspended bridge span ~350 m (e.g., Bunwajor Ghat li).

• Foundations: Must be at high elevation to provide adequate freeboard and cable anchorage.

• Walkway: Usually cambered upwards to improve clearance and drainage.

• Load Analysis:

  • Dead Load (DL): Weight of walkway + cables + suspenders.
  • Live Load (LL): Pedestrian load as per IS 875 (Part 2).
  • Cable Tension (T) can be approximated by:

  [ T = \frac{w \times L^2}{8 \times d} ]

  where
  (w) = uniform load per unit length,
  (L) = span length,
  (d) = sag of the cable.

• Material Specifications: Use high-strength galvanized steel cables and corrosion-resistant suspenders.

• Camber: Typically 1/50 to 1/100 of span length.

Key Formula Summary

graph LR
A[Main Cable] --> B[Suspenders]
B --> C[Walkway]
A --> D[Anchorage on Banks]
D --> E[High Foundation]

References:

• MORD 29 Clause 1.4 & 1.5
• Long Span Trail Bridge Standard Technical Manual (Volume A)
• IS 875 (Part 2) for live load

This ensures safe, economical, and durable suspended bridge design.

Community Involvement and Institutional Framework in bridge construction (per MORD 29 and related manuals) emphasizes participatory, multi-stakeholder processes for sustainable trail bridge projects:

Key Steps & Roles

• Community (UC - User Committee): Initiates request, contributes labor/materials, manages local maintenance.
• CDC (Community Development Committee): Prioritizes bridges, prepares investment packages, coordinates surveys/design.
• Local Government (VDC/UG): Approves plans, supports implementation.
• NGOs/Technical Agencies: Provide technical design, training, supervision.
• DOC (Department of Construction): Conducts survey, design, quality control.
• Sign-off & Agreement: Formal agreement signed by CDC, VDC, UC representatives ensuring ownership and responsibility.

Specifications & Procedures

• Formation of UC: Minimum 30% women members to ensure inclusivity.
• Material Handover: CDC/NGO hands over materials to UC for local management.
• Maintenance Committee: Formed post-construction for upkeep.
• Standardized Design & Planning: Use manuals (LSTB, SSTB) for technical consistency.

Summary Table: Roles & Responsibilities

flowchart TD
    A[Community Request] --> B[CDC Survey & Prioritize]
    B --> C[Design & Investment Package]
    C --> D[Local Govt Approval]
    D --> E[Material Handover to UC]
    E --> F[Construction & Supervision by NGOs/TA]
    F --> G[Post-Construction Maintenance Committee]

This framework ensures community ownership, technical quality, and sustainability in trail bridge projects.

Survey and Site Selection Procedures for Trail Bridges (IS Code MORD 29 Context)

Key Points:

• Site Selection:

  • Choose locations with stable rocky banks for anchoring cables (suspension bridges) or sufficiently high banks for foundations (suspended bridges).
  • Ensure freeboard (vertical clearance above water) to avoid flood damage.

• Survey Steps:

  1. Community Consultation: Engage local users and committees (UC, CDC) for site input and priorities.
  2. Preliminary Survey: Measure span, river width, bank heights, and soil/rock conditions.
  3. Feasibility Study: Assess accessibility, material availability, and environmental impact.
  4. Approval & Documentation: Submit survey data and designs to local authorities (DOC, DDC).

• Specifications:

  • Suspension bridges require towers and anchorage on rocky walls or masonry blocks.
  • Suspended bridges are simpler, built without towers, with foundations on high banks.
  • Walkways are cambered upwards for drainage and load distribution.

Typical Survey Data Table (Example)

Key Formula for Freeboard

[ \text{Freeboard} = \text{Max Flood Level} + \text{Safety Margin} (1-2 , m) ]

Conceptual Flowchart of Survey & Site Selection

flowchart TD
    A[Community Consultation] --> B[Preliminary Survey]
    B --> C[Feasibility Study]
    C --> D[Design & Documentation]
    D --> E[Approval by Authorities]
    E --> F[Construction Planning]

Summary:
Effective survey and site selection ensure structural stability, cost-effectiveness, and community acceptance for trail bridges, especially suspension and suspended types. Use local

Material Selection and Procurement for Trail Bridges (Suspension & Suspended Types)

Based on IS Code MORD 29 and related manuals:

Key Specifications:

• Main Cables: High-strength galvanized steel wire ropes.
• Vertical Suspenders: Same grade as main cables, corrosion-resistant.
• Walkway: Timber planks or steel grating, cambered upwards for drainage.
• Anchorages: Rock anchors or masonry blocks with adequate bearing capacity.
• Foundations: Must be on stable ground or rock, especially for suspended types needing high freeboard.

Material Selection Criteria:

• Strength: Yield strength and tensile strength per IS 226 or IS 432 standards.
• Durability: Galvanization thickness ≥ 200 g/m² for steel wires.
• Corrosion Protection: Use of protective coatings or paints.
• Procurement: Certified suppliers with material test certificates.

Typical Material Properties Table:

Procurement Checklist:

• Confirm material compliance with IS standards.
• Verify test certificates (tensile, elongation, corrosion).
• Inspect physical condition on delivery.
• Store materials in dry, ventilated areas.

flowchart TD
    A[Material Selection] --> B[Strength Requirements]
    A --> C[Durability & Corrosion Protection]
    A --> D[Supplier Certification]
    D --> E[Material Test Certificates]
    E --> F[Procurement Approval]

This approach ensures safety, durability, and cost-effectiveness in suspension and suspended trail bridge construction.

Stepwise Construction Process for Community Suspension Bridges (Based on MORD 29 Context)

Key Steps:

1. Community Initiation

   • Community (Fellke) submits application to District Office of the Chief (DOC) via Village Organizational Committee (VOC).

2. Technical Assessment (TA) & Survey

   • Site survey, feasibility studies, and design preparation by DOC.
   • Approval from District Council after technical vetting.

3. Investment Package Preparation

   • Based on survey and community priorities, CDC prepares investment packages.
   • Prioritization and proposal submission to support agencies.

4. Formation of User Committee (UC)

   • At least 30% women members.
   • UC responsible for local coordination and labor contribution.

5. Design & Approval

   • DOC and NGOs finalize design, drawings, and cost estimates.
   • Technical approval and sanctioning of funds.

6. Material Procurement & Construction

   • CDC and NGOs supply materials.
   • UC manages local labor and construction under supervision.

7. Handover & Maintenance

   • Completed bridge handed over to UC.
   • Maintenance committee formed for long-term upkeep.

Important Specifications & Notes:

• Walkway Camber: Upwards for suspension bridges.
• Anchorage: Rocky walls or masonry blocks.
• Span Range: Suspended bridges up to 350 m (e.g., Bunwajor Ghat li).
• Community Involvement: Essential at all stages for sustainability.

Summary Table of Roles

flowchart TD
    A[Community Application] --> B[Technical Survey & Design by DOC]
    B --> C[Investment Package by CDC]
    C --> D[Formation of User Committee]
    D --> E[Material Supply & Construction]
    E --> F[Handover to Community]
    F --> G[Maintenance by User Committee]

This structured approach ensures effective, sustainable bridge construction with community ownership, aligned with MORD 29 guidelines.

Investment and Funding Mechanisms for Trail Bridges (per MORD 29)

The document outlines a community-driven, multi-stakeholder funding and implementation process:

Key Steps & Stakeholders:

• Community Initiation: Community forms a User Committee (UC) with at least 30% women members.
• Local Government (CDC, VDC): Prioritizes bridges based on survey data and community needs.
• Donor/NGO Support: Provides technical design, funding packages, and supervision.
• District Office of the Council (DOC): Conducts surveys, prepares designs, and supervises construction.
• Funding Flow:
  • Investment packages prepared by CDC based on community surveys.
  • Funds disbursed through local bodies to UC.
  • UC manages local procurement and labor.
• Maintenance: Post-construction, a maintenance committee is formed.

Funding Data Snapshot (Example Years):

Summary Table for Investment Flow:

flowchart LR
    Community -->|Request & Labor| CDC
    CDC -->|Survey & Prioritize| DOC
    DOC -->|Design & Supervise| Community
    NGO -->|Funds & Tech Support| CDC
    CDC -->|Funds| Community
    Community -->|Construct & Maintain| Bridge

This structured approach ensures transparency, community ownership, and efficient use of funds for sustainable bridge infrastructure.

Roles and Responsibilities of Stakeholders in Community Bridge Construction (per MORD 29 & related manuals):

1. Community (UC - User Committee):

   • Initiates bridge request and submits application via VDC.
   • Provides local labor and materials.
   • Manages site during construction and maintenance post-completion.
   • Signs agreements representing users.

2. District Coordination Committee (CDC):

   • Conducts site inspections, surveys, and prioritizes bridge needs.
   • Prepares investment packages based on surveys.
   • Oversees design, drawing, and technical supervision.
   • Hands over completed bridges to UC.

3. Technical Agency (TA) / DOC (Department of Construction):

   • Performs detailed design, drawing, and quality control.
   • Provides technical support and supervision during construction.
   • Assists in training and capacity building.

4. NGOs and Supporting Agencies:

   • Facilitate community mobilization.
   • Provide technical and financial assistance.

Key Process Flow (Simplified):

flowchart TD
    A[Community Request] --> B[VDC Submission]
    B --> C[CDC Survey & Prioritization]
    C --> D[Investment Package Preparation]
    D --> E[Design & Drawing by DOC/TA]
    E --> F[Construction Supervision]
    F --> G[Handover to UC]
    G --> H[UC Maintenance]

Summary Table: Stakeholder Roles

This structured approach ensures community ownership, technical quality, and sustainability of trail bridges.

Quality Control and Supervision for Suspension & Suspended Bridges (MORD 29)

Based on the provided context and standard practices:

Key Specifications:

• Suspension Bridge Walkway: Hangs on vertical cables from main cables between towers.
• Suspended Bridge Walkway: Hangs on suspenders from main cables without towers.
• Anchorage: Rocky walls or masonry blocks on banks.
• Camber: Walkway is cambered upwards for drainage and tension balance.
• Expertise: Suspension bridges require higher expertise and cost more.

Quality Control & Supervision Steps:

1. Survey & Design Verification
   • Check site conditions, cable anchorage, foundation elevation for freeboard.
   • Confirm camber and cable tension design.
2. Material Inspection
   • Verify cable quality, masonry blocks, and walkway materials.
3. Construction Supervision
   • Monitor cable installation tension using dynamometers.
   • Ensure proper anchorage and tower erection (if suspension type).
4. Load Testing
   • Perform static and dynamic load tests to verify structural behavior.
5. Documentation & Handover
   • Maintain detailed records and provide manuals for maintenance.

Typical Formula for Cable Sag (Suspension Bridge):

[ f = \frac{w \times L^2}{8T} ] Where:

• (f) = sag (m)
• (w) = uniform load per unit length (kN/m)
• (L) = span length (m)
• (T) = horizontal tension in cable (kN)

Supervision Checklist Table

flowchart TD
    A[Site Survey] --> B[Material Inspection]
    B --> C[Cable Installation

Maintenance and Sustainability of Trail Bridges (IS Code MORD 29)

From the context on suspension and suspended bridges, key points for maintenance and sustainability include:

Key Specifications:

• Anchorage condition: Inspect cable anchorage on rock or masonry blocks for corrosion and loosening.
• Walkway camber: Maintain upward camber to prevent water accumulation and decay.
• Foundation elevation: For suspended bridges, ensure foundations remain above flood levels to maintain freeboard.
• Material durability: Use corrosion-resistant cables and treated timber or steel for walkways.
• Community involvement: Form User Committees (UC) for routine inspection, cleaning, and minor repairs.

Maintenance Checklist:

• Regular inspection of cables for corrosion and tension.
• Check anchor blocks and towers for cracks or displacement.
• Repair or replace damaged walkway planks promptly.
• Clear debris and vegetation around foundations.
• Monitor and maintain drainage to prevent waterlogging.

Sustainability Practices:

• Use locally available, durable materials.
• Train community members for ongoing maintenance.
• Standardize design and construction for easier repairs.
• Plan investment packages based on community surveys and priorities.

Example: Cable Tension Formula (for design reference)

[ T = \frac{w \times L^2}{8 \times d} ]

• (T) = cable tension
• (w) = uniform load per unit length
• (L) = span length
• (d) = sag (vertical distance between cable supports and lowest point)

flowchart TD
    A[Community Survey] --> B[Design & Approval]
    B --> C[Material Procurement]
    C --> D[Construction]
    D --> E[User Committee Formation]
    E --> F[Routine Maintenance]
    F --> G[Sustainability & Longevity]

Summary: Effective maintenance and sustainability rely on robust design, community involvement, regular inspection, and use of durable materials as per IS guidelines and field manuals.

Key Formulas & Specifications for Suspension & Suspended Bridges (IS Code: MORD 29)

Suspension Bridge (Clause 1.4)

• Main cables: Stretched between towers, anchored to rocky walls or masonry blocks.
• Walkway: Hangs on vertical suspenders from main cables.
• Camber: Walkway is cambered upwards for clearance and tension balance.
• Design Complexity: Requires higher expertise and costlier than suspended bridges.

Suspended Bridge

• No towers; cables anchored directly on high foundations on riverbanks.
• Walkway: Hangs on suspenders attached to main cables.
• Span: Up to 350 m (e.g., Bunwajor Ghat li bridge).
• Cost & Construction: Simpler and cheaper than suspension bridges.

Typical Formulas

1. Cable Sag (f) for Suspension Bridges: [ f = \frac{w L^2}{8 T} ]

   • (w) = uniform load per unit length
   • (L) = span length
   • (T) = horizontal tension in cable

2. Tension in Cable: [ T = \frac{w L^2}{8 f} ]

3. Freeboard (clearance)

   • Typically 1.5 to 2.0 m above maximum water level.

Community Bridge Construction Process (Summary)

• Community forms User Committee (UC) (30% women).
• CDC & NGOs conduct surveys, prepare designs, and approve.
• Local materials prioritized.
• Stepwise approval and construction monitoring.
• Maintenance committee formed post-construction.

Reference Tables (Example)

flowchart TD
    A[Community Request] --> B[User Committee Formation]
    B --> C[Site Survey by CDC/NGO]
    C --> D[Design & Approval]
    D --> E[Material Procurement]
    E --> F[Construction]
    F --> G[Handover &

Key Specifications & Supporting Documents for Suspension & Suspended Bridges (MORD 29)

Suspension Bridge (Clause 1.4)

• Walkway hangs on vertical cables from main cables stretched between towers.
• Main cables anchored to rocky walls or masonry blocks.
• Walkway cambered upwards.
• Requires higher expertise and costlier than suspended bridges.

Suspended Bridge (Clause 1.4)

• No towers; walkway hangs on suspenders attached to main cables.
• Foundations placed high on banks for freeboard.
• Simpler and cheaper than suspension bridges.
• Longest span: 350 m (Bunwajor Ghat li, Sunkoshi River).

Key Design References:

• Long-Span Trail Bridge Standard Technical Manual (Volume A: Design)
• Short-Span Trail Bridge Standard Technical Handbook (Volumes I & II)
• Step-wise Community Bridge Construction Procedures

Typical Design Considerations:

• Cable Tension: ( T = \frac{wL^2}{8d} )
  where
  ( w ) = uniform load per unit length,
  ( L ) = span length,
  ( d ) = sag of cable.

• Freeboard: Ensure sufficient clearance above high flood level.

• Walkway Camber: Upward curvature to reduce sag and improve drainage.

Community Bridge Construction Process (Summary)

• Formation of User Committee (UC) with 30% women.
• Survey, design, and approval by District Office of the Council (DOC).
• Investment packages prepared based on CDC surveys.
• Construction materials locally sourced and handed over to UC.
• Maintenance committee formed post-construction.

Example Table: Annual Bridge Output & Budget (Indicative)

flowchart LR
    A[Community Survey] --> B[Design & Approval by DOC]
    B --> C[Investment Package Preparation]
    C --> D[Formation of User Committee]
    D --> E[Material Procurement & Construction]