An $850 million road project connecting copper and cobalt mines in the Democratic Republic of Congo through Zambia to an East African port will cut more than 150 miles from the existing journey, according to the company building it.

Congo’s President Felix Tshisekedi and Zambia’s Hakainde Hichilema broke ground on Monday at the site where a key part of the route — a 345 meter (1,130 feet) bridge over the Luapula river that separates their countries — will be erected.

Mauritius-based GED Africa, which is backed by Duna Aszfalt Zrt., a Hungarian construction firm, will build the road. Major construction works will begin after the rainy season that’s about to start, and will take three years to complete, GED said in reply to emailed questions on Tuesday. The project also includes one-stop border posts between Zambia and Congo and tolling plazas.

The route should help ease congestion as mining companies struggle to get supplies into copper and cobalt operations in Africa’s biggest producer, and exports out. The trip over existing routes can take more than a month because of clogged border crossings and poorly maintained roads. Transportation will become an even bigger problem as production of metals,key to the energy transition expand.

“Copper, cobalt, lithium and other minerals mined in the region are critical to renewable energy technology and a low carbon future,” GED said. “The green energy transition has increased demand exponentially and as production volumes increase, road modernization is critical.”

The modernization, construction and expansion of 184 kilometers (114 miles) of highway will help truckers traveling from Lubumbashi in Congo reach the Tanzanian port of Dar es Salaam more quickly.

GED is in talks with the Trade and Development Bank and the African Finance Corporation for financing, it said. The company plans to fund it with 70% debt and 30% of its own equity.