helvetas nepal trail bridge experience

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Presentation ADB Tunis


  • 1.S.C. Kantha Team Leader Trail Bridge Support Unit Tunis, 11 Oct.2010 HELVETAS GREETINGS FROM NEPAL LAND OF THE HIMALAYAS Trail Bridge Experience in Nepal

2. Nepal in Asia Nepal a Land locked country situated between 2 Giant Countries China and India. 3.

  • Area 147,181 km2
  • Population 28 million
  • Within 170 km from almost sea levelto 8,848 m
  • Per capita GDP US $ 450

Country Background 4.

  • 75 districts, 4000 VDCs and 50,000 settlements
  • Worlds Steepest Slope
  • Worlds youngest geology

Country Background 5.

  • Landslides and road blockage very common, particularly during monsoon
  • Most diverse climate
    • Terai : 48 o C
    • Himalayas : 35 o C (-ve)
  • 80 % of land : Hills and Mountains
  • Rain : as high as 1,350 mm per year

Country Background 6.

  • 6,000 rivers and rivulets and most of them turbulent
  • Drainage density 0.3 per square km
  • Annual discharge of water 2 billion Cum.
  • Road density 14 km per 100 km 2
  • One road bridge needed at every 5.5 km

Country Background 7.

  • 4,000 pedestrian bridges are built
  • Potential demand of 6,000 bridges
  • Average beneficiary per bridge is 2,500
  • Per capita bridge cost US $ 10
  • Design life of a bridge 50 years

Country Background 8.

  • A country of diversified ethnicity, castes, cultures, religions and languages
  • Road construction very challenging because of geology and a very costly affair

Country Background 9.

  • 70% of population does not have access to roads
  • The only reliable means of transport is pedestrian bridges

Country Background 10.

  • One to two weeks non-stop walk not an exception
  • Sometimes no access for months, particularly during monsoon

Country Background 11.

  • Access to basic services-health post, post office, market, school not guaranteed
  • Lives particularly of children and women endangered
  • Foot bridge totallychange the lives of people

Country Background 12.

  • Pedestrian bridge is a must for crossing riversand having uninterrupted movement
  • Pedestrian bridges are the safe and improved means of river crossings

Country Background 13.

  • It is a very low cost project, built in a comparatively short period and benefiting the poor and the rural communities

Country Background 14.

  • For centuries people traditional means of river crossings using local know-how
  • Early 20th century, Rana Rulers built modern bridges

Evolution of Pedestrian Bridges 15.

  • 1960s
  • Based on Swiss Geologist Advice
  • Unlock the interior
  • Govt. decided to promote pedestrian bridges
  • Suspension Bridge Division established in1964

Evolution of Pedestrian Bridges 16.

  • 1970s
  • Swiss support available for the program
  • Standardization of designs

Evolution of Pedestrian Bridges 17.

  • 1970s
  • Preparation of technical manuals survey, design, standard drawings and construction
  • Workshops established for fabrication of steel parts for bridges

Evolution of Pedestrian Bridges 18.

  • 1980s
  • Withdrawal of Swiss experts
  • Huge bridge demand from people
  • Difficulties to select the most needy ones

Evolution of Pedestrian Bridges 19.

  • 1980s
  • Study of foot trails in the hill and mountainous districts
  • Preparation of main trail maps and service centre maps
  • Important trails identified

Evolution of Pedestrian Bridges 20.

  • 1990s
  • Steel decks instead of wooden planks
  • Turnkey modality applied for contracting construction works
  • Huge demands for bridges on local trail
  • SBD- construction of bridges on main trails

Evolution of Pedestrian Bridges 21.

  • 1990s
  • Helvetas initiated construction of bridges on local trails under community approach
  • Local bridge building technology upgraded with engineering input

Evolution of Pedestrian Bridges 22.

  • 1990s
  • SDC provided funds for Community Bridges
  • Bridge outputs increased tremendously

Evolution of Pedestrian Bridges 23.

  • 2000s
  • Demarcation Policy applied SSTB & LSTB
  • Technical Manuals for SSTB bridges developed

Evolution of Pedestrian Bridges 24.

  • 2000s
  • National Trail Bridge Policy effective
  • Prioritization criteria established
  • WB, ADB and DFID funds in addition to SDC available

Evolution of Pedestrian Bridges 25.

  • Capacity building through EIs
  • Course Manuals for practitioners (Eng, Sub Eng, Asst Sub Eng) developed
  • Trail Bridge course incorporated in the curriculum for engineers

Evolution of Pedestrian Bridges 26.

  • Trail Bridge sub-sector concept emerged
  • Sector-wide Approach introduced
  • Basket funds established
  • GoN, SDC, WB and DFID to provide funds in the Basket Fund

Evolution of Pedestrian Bridges 27.

  • ADB to provide funds through DRILP and RRRSDP
  • TBSU/Helvetas to provide Technical Assistance on behalf of the SDC

Evolution of Pedestrian Bridges 28.

  • TB SWAp implemented since July 2009
  • Five year Phase up to July 2014
  • Target NC 2200, MM of 500, and RM of 4,000 bridges annually and access trail improvement of 750 km
  • Budget of US $ 72 million for 5 years

Evolution of Pedestrian Bridges 29.

  • Technical assistance budget of US $ 8 million for 5 years
  • Technical Assistance to Bhutan, Tanzania, Ethiopia, Indonesia, Honduras,
  • SSTB bridge under community approach and LSTB under contracting modality

Evolution of Pedestrian Bridges 30.

  • Bridge building know-how at community level - DMBT
  • Employment at local level of 2,500 person days

Evolution of Pedestrian Bridges 31.

  • Bridge Technology
  • In terms of span
  • Short Span Trail Bridge (SSTB) : for span up to120m.
  • Long Span Trail Bridge (LSTB) : for span > 120m

Technology 32.

  • Bridge type

SuspendeD type -D-type SuspensioN type - N-type 33.

  • Technology
  • Standard Design
  • -16m
  • - 20m
  • - 24m
  • - 28m
  • - 32m

Steel Truss for span up to 32m 34.

  • The selection of the D-type or N-type dependsmainly on the topography of the bridge site.

Technology 35.

  • suitable for hills and sloped topography.
  • this type of bridge is selected where the bridge foundations can be placed at sufficiently high position giving required free board from the highest flood level.
  • is more economic, simple to design and construct than other bridge types.
  • applicable in 85% cases.

Applicability of D-type Bridge 36.

  • suitable for plane and flat topography.
  • this type of bridge is selected only when theSuspended type bridge is no more feasible due to insufficient free board.
  • thisbridge is more expensive and more complex in survey, design and construction than the Suspended type bridge.
  • only applicable in 15% cases.

Applicability of N-type Bridge 37.

  • SSTB D-type Bridge Technology
  • technology is based on
  • maximum use of local materials
  • maximum use of local skills
  • only use of simple hand tools
  • constructed by the community
  • engineering within the capacity of asst. sub-engineers

Technology 38.

  • LSTB D-type Bridge Technology
  • technology is more complex & expensive than SSTB
  • constructed at only socio-economically feasible sites.
  • engineering through Pvt. Consultants, construction through contractors.

Technology 39. Cable Setting 40. Walkway Fitting Technology Walkway Fitting 41. Tower Erection Technology 42. Cable Pulling : A critical Milestone Technology 43. Cable Hoisting Technology 44. Suspender fitting Technology 45. Wind guy System Technology 46. Tools for Construction and Bridge Erection Technology 47. Technology

  • Short Span Trail Bridge Standard Technical Handbook for Suspended Type, Vol. I, II and III (2003) - SSTB D-type
  • Short Span Trail Bridge Standard Technical Handbook for Sus