10,000 bridges
Nepal’s foot bridges have evolved from being essential for connectivity to also becoming tourist attractionsSeventy years ago, when Swiss geologist Toni Hagen explored Nepal, he had to walk because there were no roads. But the most difficult part was crossing rivers because the foot bridges either did not exist or were dangerous.
Nepal’s valleys were separated from each other not just by mountains, but also by raging Himalayan rivers. Villagers asked Hagen to help bridge the gap so they could be connected to markets and to other villages.
With the help of the Swiss government and the group Helvetas, the 10,000th trail bridge has been built, with 740 in the past year alone. Much of the original Swiss engineering design for the bridges has been passed on to Nepali companies through technology transfer.
Nepal’s trail bridges program is a model of how development projects can be sustainable through long-term collaborative effort. This has led to innovations that have transformed the lives of some 19 million Nepalis nationwide by reducing drudgery and travel time. More than 1 million students, farmers, health workers, trekkers and porters use the bridges every day. Even livestock use them to get to greener pastures on the other side.
The program is also a testament to the power of collaboration and innovation between Nepal and Switzerland. Its success in scaling-up across the entire country and adapting it to the new local governments have magnified the benefits.
The first trail bridges were built during the Rana period, with 29 steel bridges manufactured in Scotland erected between 1846-1950. Some of them are still standing to this day. Based on Toni Hagen’s recommendations, the Suspension Bridge Division (SBD) was set up by the government with the support from Swiss Association for Technical Assistance (SATA).
Each bridge took three years to design and build, compared to 18 months today. Only 10 bridges were built in the 1970s and 25 in the 1980s, but things picked up after that. A milestone was the scaling-up of the Bridge Building at Local Level (BBLL) technology and community approach supported by the Swiss Agency for Development and Cooperation (SDC) and implemented by Helvetas in 1989. This led to 100 bridges being built every year by incorporating indigenous cable bridge technology and simpler engineering.
The first Trail Bridge Strategy in 2006 was a major milestone as it set a national target that no citizen had to walk a detour of more than 1 hour in the absence of safe river crossing. Short Span Trail Bridges of up to 120m were constructed through Users’ Committees and Long Span Trail Bridges with longer spans needing contractors. A survey showed that Nepal needed 6,000 additional trail bridges.
Nepal launched three phases of the Trail Bridge Sector Wide Approach Framework (2009-2023) under which nearly 4,000 new bridges were built with other donors also stepping in.
After the promulgation of the new Constitution in 2015, local governments were given the responsibility of supervising new bridge construction and it saw a boom. The Swiss were still involved to backstop the local institutions despite initial scepticism that municipalities had the capacity to undertake the job.
But by 2019, over 8,000 bridges had been completed, and a review showed that 2,400 more bridges would be needed to fulfil the national target before the Swiss concluded their involvement.
There are significant milestones in the six decades of Swiss involvement in Nepal’s trail bridges program:
Design, Engineering and Standardisations: The development of standardised short span and long span technology and construction modalities were important in building cost-effective designs that could be scaled-up throughout the country. Handbooks with specifications were produced.
Domestic Fabrication: The Swiss Association for Technical Assistance (SATA) was instrumental in the 1960s in supporting the Nepal Industrial Development Corporation (NIDC) to establish the Balaju Yantra Shala (BYS), the first engineering workshop. Domestic fabrication of steel bridge parts eliminated the need for imports from India. Former BYS staff went on to establish private workshops outside Kathmandu for bridge parts. There are now 33 fabricators across all 7 provinces which manufacture parts for 900 bridges annually.
Main Trail Maps: The development and publication of district Main Trail and Central Service Maps through Swiss support in 1985 also contributed greatly towards the country’s overall development planning. The maps identified main and local trail networks that linked strategic central places.
Domestic Galvanisation: Wooden walkway decks were the weakest component in the traditional bridge design. They needed to be replaced frequently and were replaced by galvanised steel plates in 1995. Maintenance cost was reduced.
Foundations and Walkways: Trail bridge designs were further updated after the 2015 earthquake. Some 79 bridges were damaged out of the then 6,000 built till then. After an in-depth study of the damaged bridges, designs were refined to increase seismic resistance. Pile foundation and wider walkways in designs for the Tarai were introduced in 2009 for motorcycles and three-wheelers.
Enhancing Engineering Knowledge: Elective courses were introduced at the Bachelor of Civil Engineering with academic institutions to institutionalise trail bridge building since the early 2000s with 30 students now graduating every year with trail bridge know-how. Bridge building was also introduced as a regular course for Assistant Sub-Engineers through vocational training centres. Over 6,000 local bridge crafts-persons (30% women) have been trained in trail bridge building.
Quality Control and Maintenance: Quality monitoring has been formalised in the Comprehensive Manual on Monitoring of Trail Bridges since 2009. All fabricated bridge parts are assembled to ensure that they are fabricated as per the design. Cement quality is also tested, with the list of brands that have passed uploaded to the official website for reference. Currently, over 1,000 trail bridges are under construction in Nepal annually and these are monitored through four monitoring information systems.
Bridges to Federalisation: Swiss technical assistance for trail bridge building ended in November 2023, and local municipalities and provinces have taken over. Provincial Technical Assistance Providers (PTAPs) will work with provincial governments to continue providing technical assistance and monitoring for bridge construction independently. Provinces now have their own Trail Bridge Strategy which has increased the target to bring the detour time for people walking for essential services to 30 minutes (from the previous 1 hour) in the National Strategy.
Adapted from Trail bridge evolution in Nepal: Scaling up to reach the 10,000th bridge, Swiss Agency for Development and Cooperation (SDC).