The companies have modified six 100-tonne diesel Liebherr T 236 trucks and built a 5km test track for them at Erzberg's iron ore mine in Eisenerz.

Erzberg said that when connected to the overhead power lines in trolley mode, the full power capacity of the trucks' electric wheel motors can be translated into speed on grade while its diesel engine idles.

VA Erzberg expects to save around 3 million litres of diesel and 4,200 tonnes  of CO2 emissions per year, while also reducing nitrogen oxides and fine dust - it estimates that currently, it burns 4.5 million litres per year to transport more than 13 million metric tonnes per year of rock.

The trial has faced mining-specific challenges such as uneven terrain, the need to navigate tight bends and adverse weather conditions, said the company. The trials are taking place at altitudes of up to 1,055 metres above sea level.

Josef Pappenreiter, technical director of VA Erzberg, said standard existing overhead line technology was not directly suitable for the specific requirements at the project.

"Our newly developed technology is different from everything previously available on the market in terms of both the overhead line system and the vehicle technology itself. This could only be developed with our cooperative and innovative partner Liebherr Mining in Colmar."

"Another challenge is the electrical engineering as all six T 236 are connected to the overhead lines simultaneously in several places," said Peter Schimek, project manager for VA Erzberg.