One of the important goals of the Slovak Republic is the connection of the north and south of the Slovak Republic by expressway R3 from the Republic of Poland from the north of Slovakia (Trstená) to the national borders of Slovakia with Hungary near Šiah, where R3 will be connected to the Hungarian M2 motorway. Part of this expressway is the building “I/66 Krupina – bypass” with a length of 6.530 km.  From the point of view of the purpose function, it will be a transport building, which will be part of the international Pan – European corridor N1.The interesting area of the building in question “I/66 Krupina – bypass” is located in the Banská Bystrica Region, in the cadastral territory of Krupina. The town of Krupina, with a population of almost 8000 people, is located in the valley of the river Krupinica, on the boundary of the Krupinska Plain and Štiavnické vrchy. The building has a length of 6.530 km and is designed in the design category C 11,5/100 without considering the possibility of future extension to the four-lane category. The connection of the bypass to the existing transport network will be ensured by a pair of crossings at the beginning and end of the section with the working names Krupina North and Krupina South.The existing road I/66 as the international route E 77 passing through the town of Krupina provides, in addition to the source and destination transport, national transport in the direction of the north south of the corridor Trstená – Dolný Kubín – Ružomberok – Zvolen – Krupina – Šahy and the inter-state transit traffic on the trans-European roadway Baltic – Balaton – Adria. Therefore, the route is characterised by a high proportion of transit traffic, with a significant proportion of freight traffic, resulting in the capacity inadequacy of the existing road in peak hours, with a view to a gradual deterioration of the existing situation. The immediate proximity of the city centre and its division by road I/66 is linked to a high concentration of pedestrians crossing the road, which negatively affects the fluidity and safety of all road users. The activities of this project focus on the project preparation of the road section I/66, namely the bypass of the city of Krupina, with the aim of improving the safety and accessibility of TEN-T road infrastructure and regional mobility through the construction and modernisation of Class I roads. The building “I/66 Krupina – bypass” will perform a significant national as well as international transport function.