Charities frequently talk about building bridges with the developing world, and one NGO has been building bridges for them since 2001. But thanks to a new software tool designed by young engineers in the UK the time is in sight when they will no longer have to.
In 2010 Manuel Contreras from engineering firm Arup’s Madrid office spent three months working with Bridges to Prosperity (B2P) to build a bridge for the villagers of Cuatro Cayos, in the Livingstone District of Guatemala. The US-based charity helps communities in developing countries build simple but safe footbridges that improve access to markets, schools and medical care.
In an effort to keep the bridges they construct low-tech, up until this point the charity had only built simple 'hammock' bridges that rely on a minimum height differential between the level of the bridge and the bottom of the chasm being crossed, due to the fact they sag.
But with projects like the one in Cuatro Cayos, where the obstacle is not a deep mountain gorge but simply a wide river, this kind of low-slung design is of no use. This prompted Contreras to design and oversee the building of the charity’s first steel-tower suspension bridge.
Being able to reproduce this design had the potential to greatly widen the charity’s scope and so the management team asked Contreras how it could duplicate the success elsewhere. But as designing a suspension bridge is considerably more complex than a simple hammock bridge, Contreras approached two young Arup engineers in the UK to see if they could help.
“Manuel had been talking to the team at B2P about how to build efficient suspension footbridges as rapidly, cost effectively and sustainably as possible; could this process be condensed to as little as two weeks?” says civil engineer Phil Borowiec, who worked with structural engineer Kayin Dawoodi on the project.
“A team of us were particularly excited and passionate about the project and we began to discuss how technology could help. Over the last three years, we’ve put in time on a pro bono basis to create a calculation package, known as the BridgeTOOL which uses data such as span, height, soil conditions and available materials to test different design parameters.
“It creates drawings of the bridge and contains advice on theory and construction. It was designed so that information can simply be dropped in, without the need for specialist training and so that it can run on any normal laptop.”
Testing the tool
In order to test the tool, the pair, accompanied by six colleagues from Arup, flew to Rwanda on 19 July to help design and build a pedestrian suspension bridge over the Muregeya River that would connect the county’s Karongi and Rutsiro districts.
The bridge was completed on 2 August – less than two weeks after the team arrived – confirming the tool’s simplicity and effectiveness.
“The best way of understanding BridgeTOOL is as a bespoke calculation package. It has three main elements,” says Borowiec. “BridgeBOX allows the input of basic variables and information on available materials to calculate whether a design is viable and safe. BridgeBIM then creates drawings to help with the fabrication and construction. Finally BridgeBOOK contains detail on design principles, with advice on theory to help local communities with the construction.
“Mindful that most engineers in developing countries will have limited access to software and technology, especially those operating in rural and isolated areas, Kayin and I firmly believed that the calculation package should be easy and effective to use, by engineers and students alike, who have an understanding of simple engineering principles. It can run on any normal laptop and so doesn’t require specialist technical, modelling or data skills.”
For executive director of B2P Avery Bang, a geotechnical engineer by training, the team’s work on BridgeTOOL could not only greatly increase the number of communities they work with, but also revolutionise the way they operate.
“Over the last two years it’s been a process of them mainly contributing an immense amount of engineering time,” she says. “And now this is going to make all sorts of projects we would have to say no to, because we don’t have the capacity to do tall tower designs, possible.”
The charity has built more than 130 bridges in 14 countries across south-east Asia, Africa, and Central and South America since its inception, but as Bang says, “it’s bigger than that”.
“It’s about how to put the resources and the training technologies together so people can build these bridges without us,” she says. “I have staff right now based in countries full time, year-round, training people to build bridges, and this tool allows us to also train local engineers how to build this type of bridge too.”
Overcoming the blind spot
With most of the world’s international charities focusing on more accessible issues such as malnutrition, disease and poverty, a charity focused on building infrastructure can often find it hard to get heard.
“People don’t recognise the basic infrastructure that exists even in our own country,” she says. “Water doesn’t just flush and that road doesn’t just exist. Things like lights and electronics, stuff we take for granted, that stuff has to be engineered.”
“It is so basic to my day-to-day life in America I don’t even think about the bridges I cross and I’m a bridge engineer,” she adds. “If we can’t convince the western world’s population that infrastructure is important I don't think it’s realistic to think we will convince Ethiopian regional engineers that it is any more relevant to them.”
As a result, a big part of the charity's work abroad is surveying scores of communities to find out where bridges are really needed; where there are not more pressing projects such as a school building or a medical centre; but also to flag up the possibilities as a bridge is probably “not even on their radar”, according to Bang.
But she insists that the impact of connecting communities in what she calls the “walking world”, by building a simple bridge, is immense. With each project the charity compares local figures for school enrolment, health care visits and economic activity from before the bridge was built and five years later.
While she admits economic activity is a tricky thing to measure, they have recorded an average increase of 15 per cent after their projects, while school enrolment has increased by 12 per cent and health care visits an impressive 24 per cent.
“The charity was started on the premise that there are people around the world where isolation is literally the most significant challenge,” she says. “Often, where we are building bridges, huge percentages of children in the community, during the rainy season, don’t go to school.
“In that environment something as small as putting in a footbridge can completely revolutionise an entire region.”
But despite averaging more than 10 ten bridges a year, Bang insists the charity will never fulfil its mission unless it democratises the building process – something that BridgeTOOL has brought a step closer.
“We don’t aspire to build that many more ourselves,” she says. “To really have a huge impact we need to have hundreds of bridges built every year and that is only going to happen with training and getting bridges built without us.”