Attiki Odos (Greek: Αττική Οδός) is a private-owned motorway in Greece. The entire stretch is tolled. The Proastiakos high-speed suburban rail is almost entirely in the median through the main section. Its numbers are 6 for the main section, 64 for Imittos Ring and 65 for Aigaleo Ring. They are the outer ring roads of Greater Athens metropolitan area.
Construction of the project began in 1996. The motorway was opened along with the Eleftherios Venizelos International Airport that it connects to. The motorway ran from the Gerakas Street interchange but it didn't had access to Keratea directly until 2003 nor a northbound interchange until 2002 to Athens from Athens.
In May 2001, an interchange 20B (now K2) opened for Koropi North and reads mainly a local road. Construction from Kifissou Avenue to Gerakas continued while the western part becan construction. The Hymettus ring was under construction.
More interchanges were opened later including the Paiania-Spata Road.
In September 2002, the high-speed railway began construction and the central part of the main section began paving.
In early-2003, Attiki Odos was now operated from Kifissou Avenue to Eleftherios Venizelos Airport. The Hymettus Ring was almost paved that time but the tunnels were constructed.
In late-2003, the Hymettus Ring became fully accessible with a toll booth at the northbound lanes near Katechaki Avenue. This part of the motorway has many tunnels. It runs in the northern part of the Hymettus and became the road that bypasses Mesogeion Avenue and links to Kifissou Avenue and its suburbs and the Airport along with the eastern suburbs of Athens.
In 2004, the western section along with a tunnel opened from the junction with GR-8 to Kifissou Avenue. It has 7 interchanges in total. and runs between the mountain ranges of Aigaleo and Parnitha. The Egaleo Ring is still under construction.
The high-speed railway was complete and opened in 2004.
- Main section:
- Hymettus Ring:
The main part (official numbering):
- (Not numbered) - GR-8A
- 1 - Mandra
- 2 - Magoula
- 3 - (space reserved for future intersection)
- 4 - Aspropyrgos
- 5 - Aigaleo Ring
- 5a - Aigaleo Ring South
- 6 - Filis Ave.
- 7 - Dimokratias Ave. S of Acharnae (also known as Menidi)
- 8 - Kifissou Avenue/GR-1/E75
- 9 - Herakliou Ave.
- 10A/B - Kimis Ave.
- 11 - Kifissias Ave.
- 12 - Pendelis Ave.
- 13 - Doukissis Plakentias Ave. ( = Duchess of Plakentia Ave.) and Hymmetus(Ymittos) Ring
- 14 - Anthousa
- 15 - Marathonos Ave. (which is the continuation of Messoghion Ave.)
- 16/Y7 - Leontario (intersects with Hymettus(Ymittos) Ring)
- 17 - Kantza
- 18 - Paeania
- 19 - (space reserved for future intersection)
- 20 - Markopoulo Mesogaias/Eleftherios Venizelos Airport
Markopoulo to Eleftherios Venizelos:
- K1 (20A) - Attiki Odos
- K2 (20B) - local road (Koropi North)
- Y1 - Katehaki Ave.
- Y2 - Papagou
- Y3 - Dimokritos
- Y4 - Agia Paraskevi ( = St. Paraskevi)
- Y5 - (space reserved for future intersection)
- Y6 - Glyka Nera
- Y7/16 - Leontario (see above)
- Y8 - Pallini
The brackets are non-state highway numbers.
- Attiki Odos (6) - 47 km
On October 21, 2005 a new extension plan was proposed. 76 km of motorway will be constructed, bringing the total length to 141 km. Extensions will be constructed towards Rafina, Lavrio and Vouliagmeni. The Hymettus Ring will also be extended southwards to Vouliagmeni. It is yet unknown when construction will start, but it is estimated to begin in 2007.