The EU is supplying €552.6 million, which will be used to improve the motorway that connects Hungary's industrial city Miskolc with Tornyosnémeti, lying on the border with Slovakia.
The work will include widening a 60km stretch of the existing route and constructing 48 new bridges.
Construction is expected to be complete in the first quarter of 2022.
The project is being financed through the EU's Cohesion Fund and is expected to reduce congestion, while boosting capacity and safety on the route. ■