Single carriageway in the context of "Central reservation"

National Road 20 (Greek: Εθνική Οδός 20, abbreviated as EO20) is a single carriageway road in northwestern Greece. It links the cities of Ioannina and Kozani via Konitsa and Siatista. It passes through the Ioannina, Kastoria and the Kozani regional units. Since the opening of the A2 motorway (Egnatia Odos), it is no longer the fastest connection between Kozani and Ioannina. The section between Ioannina and Kalpaki is part of the European route E853.

Greek National Road 3 (Greek: Εθνική Οδός 3, abbreviated as EO3) is a single carriageway road in Greece. It connects Elefsina near Athens with the border of North Macedonia at Niki. It passes through Larissa and Florina. At Niki, it connects with the M5K motorway to Bitola. The section Kozani - Niki is also designated as the A27 motorway, part of which is operational as a 2-lane motorway.

Greek National Road 3 is one of the longest national roads in Greece and until the 1960s it served as the main route from Larissa to Thessaloniki. The A1 motorway now offers a faster connection to Thessaloniki. Most of the EO3, except the southernmost section between Eleusis and Bralos, is part of the E65.

National Road 48 (Greek: Εθνική Οδός 48, abbreviated as EO48) is a single carriageway road in central Greece. It connects the Greek National Road 5 at Antirrio with the town Livadeia, passing through Naupactus and Delphi. The section between Antirrio and Itea is part of European route E65. The GR-48 passes through the regional units Aetolia-Acarnania, Phocis and Boeotia.

National Road 38 (Greek: Εθνική Οδός 38, abbreviated as EO38) is a single carriageway road in western and central Greece. It connects Thermo with Lamia, via Agrinio and Karpenisi. It passes through the regional units Aetolia-Acarnania, Evrytania and Phthiotis. One section coincides with the European route E952. The E962 goes between Agrinio and Lamia.

Greek National Road 7 (Greek: Εθνική Οδός 7, abbreviated as EO7) is a single carriageway with at-grade intersections in the Peloponnese region in southern Greece. It connects the cities of Corinth and Kalamata, via Nemea, Argos, Tripoli and Megalopoli. It has been succeeded in importance by the A7 motorway (Corinth–Tripoli–Kalamata).

Greek National Road 2 (Greek: Εθνική Οδός 2, abbreviated as EO2) is a single carriageway with at-grade intersections, located in the regions of West Macedonia, Central Macedonia and East Macedonia and Thrace. It connects the Albanian border near Florina with the Turkish border near Alexandroupoli. Its section east of Thessaloniki has been replaced by the new A2 motorway (Egnatia Odos). The section between the Albanian border and Thessaloniki is part of European route E86.

A dual carriageway (BrE) or a divided highway (AmE) is a class of highway with carriageways for traffic travelling in opposite directions separated by a central reservation (BrE) or median (AmE). Roads with two or more carriageways which are designed to higher standards with controlled access are generally classed as motorways, freeways, etc., rather than dual carriageways.

A road without a central reservation is known as a single carriageway regardless of how many lanes there are. Dual carriageways have improved road traffic safety over the years and over single carriageways and typically have higher speed limits as a result. In some places, express lanes and local or collector lanes are used within a local-express-lane system to provide more capacity and to smooth out traffic flows for longer-distance travel.

Sturt Highway is an Australian national highway in New South Wales, Victoria, and South Australia. It is an important road link for the transport of passengers and freight between Sydney and Adelaide and the regions along the route.

Initially an amalgam of trunk routes, the Sturt Highway was proclaimed a state highway in NSW in 1933. In 1955, the route was allocated a National Route number (20). It was included in the National Highway system in 1992, forming the Sydney-Adelaide Link. Sturt Highway is allocated as route A20 for its entire length, the majority of which is a single carriageway, and freeway standard and 6-lane arterial road standard towards its western terminus in Gawler.

National Road 5 (Greek: Εθνική Οδός 5, abbreviated as EO5) is a single carriageway road in western Greece. It connects Antirrio, at the north end of the Rio-Antirrio bridge, with Ioannina in northwestern Greece, passing through Agrinio and Arta. The southern part, between Amfilochia and Antirrio, is part of the European route E55. The northern part, between Ioannina and Amfilochia, forms the European route E951. It passes on the east side of the Ambracian Gulf. In the future much of the traffic that used this road will be diverted to the new A5 motorway (Ionia Odos) motorway, which has already taken over parts of the road. Νear Arta there is a 200m. tunnel (Kleisoura tunnel) which opened in 1969