C40 Good Practice Guides: Tokyo - Thermal-barrier Coating and Water-retentive Pavement

Summary

Tokyo Metropolitan Government (TMG) is promoting cool pavements by including thermal-barrier coating and water-retentive pavement installation as a part of road maintenance and construction within the priority areas in central Tokyo. TMG has coupled these innovative pavements with the upcoming summer Olympics by building them along the marathon tracks for the games and on roads around the venues. Since the Metropolitan roads were being updated, the city has incorporated the pavements as a part of road maintenance and construction. For the municipality roads, TMG is providing subsidy for Thermal Barrier Coating pavements.

Results

The project has supported development of 84 km of cool pavements with 65 km of thermal-barrier coating pavements and 19 km of water-retentive pavements. TMG plans to expand these by 10 km every year until 2020 with a target of 136 km of cool pavements by 2020. The thermal barrier coating reduces the surface temperature and makes it at most 8 degrees Celsius cooler than a regular asphalt pavement.

On the other hand, water-retentive pavements suppress the temperature rise of road surfaces to a maximum of 10 degree Celsius through water evaporation.

Reasons for success

This project was a success because it coupled the environmental benefits of cool pavements with larger infrastructure projects. Incorporating the cool pavements into the development plans for the Olympic games and providing subsidies for municipality roads made the project easier to implement. It significantly reduced the burden of making a business case for cool infrastructure and helped securing funding that otherwise might not have been available for a cooling project. In addition, the availability of cutting edge technology, such as water-retentive pavements, was also a considerable factor in making it a success.

When/why a city might adopt an approach like this

This approach works well in cities where large/long-term infrastructure projects are underway or planned, and the city has control over the technology and procurement decisions for these projects. It also requires access to technology in order to implement an array of solutions. 

C40 Good Practice Guides

C40's Good Practice Guides offer mayors and urban policymakers roadmaps for tackling climate change, reducing climate risk and encouraging sustainable urban development. With 100 case studies taken from cities of every size, geography and stage of development around the world, the Good Practice Guides provide tangible examples of climate solutions that other cities can learn from. 

The Cool Cities Good Practice Guide is available for download here.  The full collection of C40 Good Practice Guides is available for download here.  

All references can be found in the full guide.