Transforming a busy road into a public open green space in Bilbao, Spain

Key Learnings

About the Region

Climate Threats

Floods

Figure 1: Flooding return periods of the Nervion River. Image Credit: Bilbao City.

Heat Waves

Figure 3: Projected temperature increases under RCP 4.5 and RCP 8.5 emission scenarios for Bilbao. Image Credit: Bilboa City.

In recent years, temperatures have been severely increasing, with heat waves becoming more frequent, longer and with higher temperatures. The Intergovernmental Panel on Climate Change has calculated temperature trends under different representative CO₂ concentration pathways (RCP 4.5 and RCP 8.5, Figure 2), estimating prolonged and higher temperatures in the next 15 to 75 years.

Adapting a heavily used road to climate change by turning it into a green corridor

Before adaptation, Mª Díaz de Haro Street had three lanes, parking on both sides, and two-metre-wide pavements. To address rising temperatures and flood risk, the city council transformed it into a more welcoming space, replacing asphalt with permeable surfaces and adding greenery to enhance outdoor quality for residents.

The adaptation project has two building phases, with the first section starting at Simon Bolivar Street to Autonomía Street, and the second section ranging from Gran Vía to Simon Bolivar Street by redesigning 700 metres of road in total.   

The greening measures continue Dña. Casilda Garden’s green infrastructure with trees and green spaces along the road. The measures include creating more space for pedestrians and increasing outdoor quality by transforming two lanes and car parking areas into green areas.

Figure 3: Mª Diaz de Haro Street from Simon Bolivar Street. Before and after de intervention: Image Credit: Bilboa City.

Widening the pavement from two to at least four metres and adding a central park created dwelling areas and shaded spaces. The new design enhances connections between existing green spaces, incorporates additional greenery like trees, and maintains functionality for residents, including local commerce.

Previous state

The plan below shows road before implementing the adaptation measures. The space included almost 3,000 m² of pedestrian and over 5,600 m² of road area, totalling more than 8,500 m² of sealed surfaces and strongly influencing urban heat in the space.

Figure 4: Street configuration before works. Image Credit: Bilbao City.

Road state after implementing the adaptation measures in the first street section

Figure 5 shows the road after implementing the adaptation measures with over 4,500 m² of pedestrian area equipped with permeable surfaces, a green corridor with deciduous, perennial and native species, adding almost 1,300 m² of retention area to the space and the road area reduced by over 2,800 m², significantly lowering traffic volumes.

Figure 5: Final design in the first section. Image Credit: Bilbao City.

Measuring heat reduction to assess effectiveness

After implementing the greening measures, the council’s sustainability department assessed their effectiveness. Thermal comfort (how comfortable people feel outdoors) was evaluated using the Physiological Equivalent Temperature, comparing how warm or cold a person feels in the given environment, before and after implementing the measures under changing climatic conditions. A third calculation estimated ways to optimise the greening measures for improved outdoor quality. Figure 6 shows that greenery reduces the Physiological Equivalent Temperature.

Figure 6: The image shows how public space Physiological Equivalent Temperature improves by implementing green infrastructure. Image Credit: Bilboa City.

The effectiveness of planting greenery –key for climate resilience - becomes increasingly important under rising temperatures. When Physiological Equivalent Temperature exceeds 41°C, calculations show that these measures lower perceived temperatures across all future scenarios.

Additional actions to tackle heatwaves

Besides implementing greening measures, Bilboa city authorities asked the project team to:

• Calculate the maximum green infrastructure implementation capacity to achieve thermal comfort under hotter conditions than today
• Create, maintain and improve the Climate Refugee Network to help the population avoid heat waves. The Climate Refugee Network includes open spaces (65) and buildings (66), where people can go when heat stroke occurs. Trained employees provide first aid.
• Develop a heatwave protocol to provide guidance and implement prevention measures when high temperatures occur in the city. The protocol is a list of recommendations announced by the city council in the mass media, informing the population what to do and not do during extreme heat. The recommendations, for example, include not doing sports at midday.
• Include implementation criteria in urban plans that require green infrastructure, such as trees, and blue infrastructure, such as fountains.Include climate change indicators (surface permeability, retention capacity, canopy cover for shading, etc.) in tendering projects.

Turning from taking green infrastructure as ornamental to considering it as a service will help to face climate change hazards, mainly, heat waves.

Mikel González Vara, Head of Environment Department, Bilbao

Project success

• The first success has been public acceptance, as people have realised that even in a densely built-up area, it is possible to create a more pleasant, healthy, and comfortable environment.
• It remains essential to monitor additional ecosystem services, as climate change hazards require diverse responses. However, some health benefits, such as improved air quality and reduced noise, are already evident.

Figure 7: Simon Bolivar Street before (left) and after (right) the greening measures. Converting a three-lane road into a one-lane street and creating a new public space. Image Credit: Bilbao City.

Figure 8: From Simon Bolivar Street before (left) and after (right) creating public spaces. Image Credit: Bilbao City.

Summary

Figure 9: From Simon Bolivar to Autonomia Street. Before and after implementation. Image Credit: Bilbao City.

Further Information

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