ICE Graduate Member and Buro Happold engineer Nii Amanor Dodoo-Amoo tells us about his rewarding trip to build a bridge connecting an isolated village in Rwanda, and why he feels engineers have a responsibility to society.
Rural isolation is a root cause of poverty. Bridges to Prosperity (B2P) is a charity that provides isolated communities with safe access to essential health care, education, market and economic opportunities by building footbridges. B2P designs, builds, and maintains durable and environmentally sustainable footbridges to connect rural communities. It's is able to do this with the help from industry partners and expert volunteers. I am one of those volunteers.
The Gatare footbridge
The organisation Europengineers, the Nyarugenge District of Rwanda and B2P partnered to build a footbridge across the river Yanzi to provide a safe, year-round crossing for the local Gasiza and Rubonobono communities of Gatare in Rwanda. The Nyarugenge District and Europengineers jointly funded the cost of the bridge.
This crossing – a 37m suspended cable footbridge – provides the local villages with access to a market, a health clinic and primary school, and is the only safe crossing in the wet season.
I and Sam Youdan, a structural engineer also from BuroHappold Engineering, were jointly awarded an ICE QUEST Travel Award to help fund our trip. We were joined by eight other engineers and consultants from the member companies of Europengineers.
Over the course of two weeks in November 2018, our team was tasked with the construction of the superstructure of the suspended bridge.
Getting ready
In July 2018, preparation for outbound travel to Rwanda started. The team was spread throughout Europe with representatives from Spain, Greece, Switzerland, France, Ireland, United Kingdom and Ireland.
Team introductions were made in early August via teleconference with follow-up calls to prepare and plan for the trip and construction covering aspects such as in-country logistics, food and housing, the construction, and health and safety plans. It was important to understand the full scope of the build given the short time that the team would be present on the ground in Gatare.
Bridge construction
The bridge consists of two handrail cables and two deck cables. The deck was formed with 38 steel cross beams, located at 1m centres made with a combination of steel and timber and placed on top of the walkway cables.
The walking surface consists of a series of 2m-long timber planks, placed five abreast, laid on top of the cross beams. The cross beams were connected firstly to the cables by 10mm diameter reinforcing bars acting as stringers, and secondly, to the walkway cables by manually bending the stringer around both the cable and the cross beams.
For the handrail cable connection, the stringer was manually looped around the handrail cable. A wire mesh was then attached to the handrail cable and deck to ‘fill the gap’ between the cables.
The cables were anchored in both abutments by passing them through a concrete anchor beam and clamping the cable against itself with a series of drops forge anchors. When our team arrived on site, the abutment walls and tiers had been built, so once the cable sag was set, the abutments were backfilled with stones of varying sizes and layers of mortar.
Finally, fence posts were installed, and a 100mm-deep approach slab was formed over the entire top surface of the abutment.
A series of workstations were constructed with scrap timber. These would provide stable and comfortable work areas.
On these workstations, the production of deck units proceeded. This involved the marking cutting and treating of the timber boards for the deck.
The timber on the bridge was treated with diesel to protect it from weathering and extend the life of the decking. The steel elements of the bridge were similarly marked cut, drilled and painted.
The deck units consisting of the steel cross beam, the timber nailer board and the steel suspenders were assembled on ground level and installed on the bridge. The reinforcement bars used as suspenders for the deck united were bent around the suspended cables.
The two abutments of the bridge were back filled after the suspended cables were secured into the concrete cross beam ensuring the correct cable sag had been achieved. A finished concrete topping of 100mm was cast onto the filled approaches to provide a safe walking path and smooth out the irregularities from the back filling.
The people
A key element of the trip was engaging with the local workforce on the build site and the wider local community.
A successful bridge could only be achieved if the Gatare people could form a connection with the bridge so throughout all stages of the build we ensured that significant elements of the construction were explained and walked through with the local workforce on site.
In addition, we held several meetings with the wider local community to introduce ourselves and to discuss the bridge and its construction.
The part I enjoyed most about my trip to Rwanda was the people who gave us a heart-warming reception. It's a beautiful place and it was amazing to work side-by-side with the local communities on the construction site. We shared laughs, language and skills, and I thoroughly enjoyed it.
Challenges
We faced a few challenges in the build of the bridge. Planning and preparation had been carried out prior to travel, but translating those plans into action on site wasn't straightforward.
English was the common language for the team, but was not the first language of all the overseas team and the local community don't speak English.
This posed a significant challenge in communication. We had a translator engaged for the project, but we also learned some key words in the local Kinyarwanda language, which helped, and used hand signals.
Another challenge for any project like this is making sure that the infrastructure has longevity by looking after it and effecting repairs when needed.
For the Gatare bridge, a committee, formed from the local workforce who played an integral part in the bridge construction, were elected to be the wardens of the bridge. This bridge committee will maintain the operation of the bridge using the skills and knowledge they developed on the project.
Beyond infrastructure
The bridge serves 2,704 community members, ensuring a safe and reliable means of access across the Yanzi river.
The presence of the bridge goes beyond a physical piece of infrastructure. The bridge shall also serve as a foundation for new opportunities for the Yanza and Rubonobono communities in Gatare.
The bridge will serve as a physical and social connection for the people. It's the hope that the bridge shall spur new economic opportunities, improve healthcare, increase access to education and promote freedom of movement.
The Gatare suspended bridge project tackles several of the UN sustainability goals by helping end poverty, ensuring healthy lives through safe access to health care, ensuring inclusive and equitable access to education and making human settlements safe, resilient and sustainable.
I believe as an engineer, it’s my duty to use my skills to influence the lives of others in a positive way. This is underlined in the rules of professional conduct for ICE. The Gatare bridge demonstrates this social responsibility in action and I’m so proud to have been a part of it.
