Building resilient roads in Samoa
Building weather-resilient roads is a topic of increasing concern everywhere, most especially in places like the Pacific Islands, which are isolated, spread out, small in population and particularly threatened by climate change.
Many important roads lie next to the sea, barely above sea level, and are without drainage. They’re often badly maintained and governments don’t have the resources for repairs or rebuilding.
To best protect roads from the ravages of extreme weather, the World Bank supports adaptation and resilience, which is building a road, or bridge, to be somewhat resistant to climate change.
In Samoa, a World Bank project aims to build resilience into the restoration of vital roads and bridges damaged by extreme weather.
The project came in response to Tropical Cyclone Evan, which wreaked havoc on Samoa. The government estimated damages from the cyclone at about US $210 million, equivalent to about 30 percent of the total value of goods and services produced in the country in 2011.
“As the task team saw with its own eyes, a severe rainstorm (not even a cyclone) can make roads or bridges impassable,” says Sean Michaels, an infrastructure expert at the World Bank who is co-managing the resilience project.
“On the island of Savaii a key bridge was impassable for eight hours, providing residents with limited connectivity to the nearby hospital and schools. That bridge is one of the funding targets under the project.”
On Kiribati, engineers are incorporating climate resilience into rebuilding the country’s main South Tarawa road.
The 33 kilometre road stretches from the Betio business district in the west to the airport at Bonriki in the east, with eight kilometres of feeder roads, tidal barriers and speed humps thrown in to make the roads safer.
One of the first steps in rebuilding the South Tarawa network was to identify the beaches, near the road, that are most eroded. In some cases, the erosion is only a few meters from the road itself. Road designers are also planning for heavier rainfall and a rising sea level, and working on seawalls to protect the road from the sea.
“Tarawa is one of the most densely populated spots on the map-- 58,000 people living on a very thin stretch of land,” says Franz Dress-Gross, the World Bank’s country director for Kiribati. “There were a lot of coastal defences that had to be strengthened to make sure that the road would be safe from erosion effects from the sea. The type of pavement that was used is particularly resilient to heavy rainfall and, as you know, with climate change we expect stronger peak rain events as well as prolonged drought.”
Both the Kiribati and the Samoa projects are funded by IDA, an arm of the World Bank that works with the world’s poorest countries.
But all around the world, countries are making huge investments in transport infrastructure—those investments are estimated at $1.4 trillion to $2.1 trillion a year. And since bridges, roads, and rail lines can last for decades, the issue of building for climate change becomes imperative now.
That’s why over one-fourth of the Bank’s transport portfolio supports climate mitigation and adaptation.
• With support from the World Bank, engineers around the world are tracking, studying, and planning to build infrastructure that can withstand weather ranging from El Nino to raging sandstorms to massive high tides.
• To do that, engineers first assess the weaknesses in a few main road sections.
• They evaluate the risk posed by climate change and the economic consequences of damage to the road sections.
• Then they make recommendations as to how to improve the roads’ resilience. Suggestions range from using re-siting roads, using different building materials, raising road levels and planting vegetation in order to stabilize slopes.
In Samoa, the government is using outreach and meetings to get communities thinking about road resilience. Engineers are using high-resolution aerial photography to map the most vulnerable roads.
After Cyclone Ian hit Tonga hard, the country is working on analysis of storm tides, waves and sea level rise. In Kiribati, the push is to raise seaside roads to so-called “no regret” levels. In Samoa, the goal is “no-regret” level roads combined with a move to relocate roads and people away from the coast. In all three nations, experts acknowledge that good roads are vital for economic development, but they face a lack of resources.
The approach has to be multi-pronged, says Sean Michaels. “There’s no silver bullet to enhancing road resilience,” Michaels says. Governments need to use tools ranging from risk-based planning, to uniquely designed infrastructure, to making sure laws and regulations can support adaptation, to, ultimately, supporting post-disaster recovery.
And, Michaels says, it is important to make sure stakeholders—especially ones with limited funds—stay committed. Financial incentives, like grants, can certainly help, but it is equally important that supervisors keep a close and careful eye on progress, to make sure workers stay on course to meet their resilience goals.