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Digital Twin Helps Raleigh, N.C., Foresee, Combat Urban Heat

The city, part of North Carolina's Research Triangle, is using a digital twin model empowered by GIS and artificial intelligence to plan for and address urban heat. It drives understanding of how development and heat will interact.

Buildings in a city are overlayed with cyan-colored lines to represent a digital city or digital twin
Shutterstock/Pavel Chukhov
The city of Raleigh, N.C., has used GIS technology to create a digital twin model to inform city work and urban heat mitigation, and is now now weaving in artificial intelligence (AI) to prepare for future conditions.

GIS technology has been used to inform heat mitigation levels in New Orleans and Washington, D.C., and some experts argue it can be an effective tool to fight climate change. In Raleigh, GIS is informing three ongoing initiatives: the Cool Roadways Pilot Project, Street Tree Equity and Green Stormwater Infrastructure, according to Jim Alberque, GIS and emerging technology manager for the city’s IT Department.

Alberque has been with the city for more than a decade, and in this endeavor, he began by trying to get a higher-fidelity urban model of current heat conditions. To do so, Raleigh acquired data from commercial data providers and lidar technology. Using tools in Esri’s portfolio, the city was able to create a visual model of conditions.

There are limitations in using a model of current conditions, Alberque explained, because Raleigh is a rapidly growing city and changes quickly. But as the city evolves, so does its technology; in 2020, the city had been marketing the digital twin mechanism as a way to share these urban environment changes visually. Essentially, a digital twin is a virtual model of an object — in this case a virtual model of the city of Raleigh — which officials use to analyze the environment and simulate changes.

In 2021, a grant from the National Oceanic and Atmospheric Administration funded the implementation of heat sensors in the area, enabling access to new data capabilities for surface temperature mapping. When the city obtained this data, the team wanted to share it and make it accessible; and so, using its digital twin model, the city was able to make heat data more engaging in a 3D environment. Alberque said the method received a lot of traction.

Simultaneously, the city was exploring heat mitigation initiatives. With the digital twin, the city was able to engage stakeholders using heat island data to strategically plan projects in the city — specifically, to inform the Cool Roadways Pilot Project, Street Tree Equity and Green Stormwater Infrastructure projects. The visualization helped the city use a data-informed perspective to plan and target specific areas that would most benefit.

The city is using data visualizations in a several ways. First, the digital twin is the mechanism by which the data is being shared publicly. For the analytical piece, which also uses Esri technology, the city is using the county’s social vulnerability index to center equity in decision-making. For example, officials have prioritized streets in the hottest 25 percent of the city for cool pavement investments.

The data visualizations also help build buy-in for investments, to assure stakeholders that investments are made equitably, and that impact is maximized — and GIS helps answer those questions. The city’s heat mitigation initiatives existed prior to the use of GIS, Alberque said — but only in pockets, and without a data-driven process guiding them.

But the other major value of GIS, he said, is that it plays a key role in storytelling when delivering services to citizens.

“We’re trying to deliver good services, but it’s important for us to tell a story around that,” he said. “And so, this technology also helps us — not only on the analytics, operations [and] decision-making side — but also, on that storytelling side, as well.”

These three primary heat mitigation projects are ongoing. The cool roadways investments, which involve applying titanium dioxide, started with a pilot — but in the future will be incorporated into the city’s resurfacing program. The Green Stormwater Infrastructure project continues with city and residential projects. The Street Tree Equity project will expand with a newly awarded $1 million grant from the federal Department of Agriculture. Staffers planted between 300 and 350 trees in January and will plant the same number in January 2025.

The city worked with the company MITRE, Alberque said, after seeing its use of high-resolution meteorological models, to do microclimate modeling based on future conditions for a separate project. Officials realized the value of high-resolution heat island mapping in doing neighborhood-level analysis — even building-level analysis — and collaborated with MITRE to make the visualizations meet the city’s needs. Here, Raleigh’s investments in a digital twin enhanced the output of this platform, Alberque said.

The digital twin served as an input to the microclimate modeling tool, layered with information related to weather conditions in 2050. AI is built into the underlying technology model to create these future scenarios. The tool models future weather conditions as they relate to the current urban landscape. The city is able to integrate potential future developments into the visualization to see how conditions may change and how future development may impact heat.
A birds-eye view of Raleigh in a digital model shows heat data with the colors of blue, green, yellow and orange.
Screenshot of microclimate model used by Raleigh to map future urban heat conditions.
Courtesy of the city of Raleigh.
There has been a lot of regional interest in the city’s work, Alberque noted, as neighboring localities are experiencing similar urban heat trends.

For other cities exploring similar tools, the GIS and emerging tech manager pointed out Raleigh's creation did not happen overnight, but rather, took years of work. He credited city leadership for not just supporting innovation, but mandating it.

“We were lucky enough to be in the Research Triangle area where there is this expectation of doing new and interesting things to solve some of the challenges that are coming,” said Alberque.
Julia Edinger is a staff writer for Government Technology. She has a bachelor's degree in English from the University of Toledo and has since worked in publishing and media. She's currently located in Southern California.