Vehicles drive on the Nairobi expressway in Nairobi, Kenya, Dec. 22, 2022. (Xinhua/Han Xu)

Nairobi, the capital of Kenya, harbors the dream of becoming a green city, with the government and private developers ensuring that the projects they undertake are climate-smart.

From roads to buildings, the city is making great strides towards realizing the green dream, one project at a time.

Leading from the front in making Nairobi a friendly city to the environment are Chinese projects, with the Nairobi Expressway standing out not only as an architectural masterpiece but also as a monument in environmental conservation.

Linking the Mlolongo, south of Nairobi, and Westlands in the west, the Expressway takes care of the environment in a way never seen before in the East African nation.

To begin with, flowers planted in pots spruce up sections of the 27-km thoroughfare, making it not only beautiful but also environmentally friendly. Then there are also other plants like bougainvillea, and grass grown on the ground at different sections of the road to eliminate soil erosion.

Also, growing various plants in plastic trays beautifully supports the massive pillars that suspend sections of the road, a first in East Africa's biggest economy. These plants take in carbon dioxide emitted by vehicles and give out clean oxygen.

"I like the idea of growing the plants on the pillars. It is not only unique but shows how we can take care of the environment using simple ideas," said Christine Majali, an environmental enthusiast.

Julia Ondeyo, a deputy director at the Kenya National Highways Authority, said in a recent interview that the character of most of the engineering structures has been that they don't create a peaceful environment for people as they travel through.

The Nairobi Expressway infrastructure, according to her, has blended environmental aspects in its design, starting a novel way of building roads in Kenya.

"These plants are creating a carbon sink in the fight against climate change as they absorb carbon dioxide generated by the vehicles and clean the air," she said, adding that besides the flowers, more than 3,000 trees have been planted along the road.

The biggest environmental advantage of the Nairobi Expressway lies in the fact that it has cut travel time from two hours to 20 minutes along the key artery that is part of Kenya's Northern Corridor, linking the port of Mombasa and the hinterlands.

More than 70,000 vehicles use the Nairobi Expressway daily, according to Moja Expressway Chief Executive Officer Steve Zhao.

These vehicles, the majority of them using fossil fuels, include saloon cars and commuter minibuses, commonly known as matatus in Kenya. While the saloon vehicles have a fuel capacity of about 40 liters, the minibuses have 70 liters.

"If I use the Expressway during peak hours in the morning and evening, the 70 liters I fuel lasts me slightly over a day. But if I use the lower road, it only lasts a day," said John Wafula, a matatu driver with Rembo Classic that plies the Nairobi-Kitengela route.

The reduced fuel consumption means a decline in carbon emissions from Kenya's public transport sector, one of the biggest contributors to greenhouse gas emissions in the country.

In a 2022 study on carbon emissions of greenhouse gases like carbon dioxide (CO2), nitrous oxide (N2O) and ozone (O3) on Nairobi roads in five years, four Kenyan scholars of the University of Nairobi -- Cynthia Sitati, Christopher Oludhe, Leah Oyake and Aderiana Mbandi -- found that matatus had emitted 6.89 million grams of carbon dioxide equivalent (gCO2e), light commercial vehicles 1.82 million gCO2e, heavy goods vehicles 251,683 gCO2e and motorcycles 181,054 gCO2e.

Private vehicles, according to the study, were the highest contributors to carbon emissions with a total of 25.3 gCO2e during the five years.

While matatus have found the Expressway a perfect road to aid them earn more and save on fuel, a majority of the 70,000 vehicles that use the road every day are private cars, therefore, cutting down on carbon emissions due to reduced travel time.

"Every motorist in Kenya should use the Expressway as part of the efforts to protect the environment, the cash saved on fuel notwithstanding," said John Kariuki, a telecommunication engineer, who lives in Kitengela, south of Nairobi, and uses the road every day.

According to MOJA Expressway, the Chinese firm that runs the toll road, if a motorist makes 10,000 trips on the Expressway and pays using the electronic option, they save about 314 liters of fuel.

"The Nairobi Expressway not only reduces travel time but also minimizes fuel consumption," the company notes.

MOJA Expressway is also supporting other green initiatives targeting the road, as it recently joined hands with Kenyan matatu saccos Super Metro and Metro Trans, which launched a new direct route via the Expressway from Nairobi central business district to the main airport Jomo Kenyatta, some 18 km away.

"In line with our drive towards a greener future, the new route will be covered using electric buses promoting sustainability by lowering carbon emissions and saving fuel," the firm said.

Kenya, in its Nationally Determined Contribution (NDC), a climate change action plan, is committed to reducing greenhouse gas emissions by 32 percent by 2030.