D4 motorway (Slovakia)
The D4 motorway is a Slovak motorway which, when completed, will form the outer ring road around Bratislava, speed up access to motorway networks and partially reduce traffic on the road network in the catchment areas of Bratislava. The D4 is one of Europe's largest public-private partnership projects.
For decades, there was only a short stretch from Austrian border at Jarovce to the junction with D2, construction of which started in 1996 and was opened in 1998.
Construction of various other parts started in the late 2010s, with several openings throughout 2020 and 2021. The extension to the motorway D1 in Bratislava is underway, in order to connect the southern bypass of Bratislava to the country's main traffic artery. The outer ring road also intersects with expressway R7; parts of which are already open as well. The motorway is toll-free with an exception for the section after the D2xD4 junction to the Austrian border.
Chronology
The connecting motorway on the Austrian side, Nordost Autobahn A6 was opened on 19 November 2007. The highway connects the border with Slovakia to the Ost Autobahn A4. It provided connection to 3rd of its 5 neighboring country. Until 2007, Slovakia was connected by motorway only to the Czech Republic and Hungary.In 2016, the construction began of the motorway section from the D2xD4 junction near Jarovce to Bratislava, Rača. All the section was set to open in 2020, which was delayed due to construction problems. Therefore, only the Bratislava, South - Bratislava, Podunajské Biskupice and the Bratislava, Podunajské Biskupice - Bratislava, Vrakuňa sections were opened in 2020. The rest of the section opened in the fall of 2021. However, the D1xD4 junction has been delayed all the way to the year 2026.
On 24 November 2024, the slip road at Bratislava-vychod was put into operation, in the direction of D1 towards Trnava.
Future developments
Funded by a PPP project, the Bratislava-Rača – Bratislava-Záhorská Bystrica section is planned for future construction. As of 2025, the planned construction start date is at the end of 2029 and the planned completion date is in 2036.Tunnel
The PPP project also includes the Karpaty tunnel. With the length of, it will become the longest tunnel in the country and one of the longest in Europe. It is estimated that the tunnel will cost around 1.6 billion euros.| Tunnel | Length | Notes | Speed limit |
| Karpaty | 10,980 | construction planned to begin in 2029, planned to open in 2036 |