Otoyol 31, named the ðzmir-Denizli Motorway () and abbreviated as the O-31 is a long toll motorway in western Turkey. Beginning at an intersection with ðzmir Beltway, the O-31 runs south from ðzmir to Denizli and parallels the D550 and D320 for most of its route.
The O-31 begins at Ià Âñkkent interchange, a trumpet interchange with the ðzmir Beltway (O-30) in southeast Buca, ðzmir, outside the urban city zone. From there, the route heads south through the recently closed Ià Âñkkent Toll Plaza until reaching the Lesser Menderes Plain. The motorway crosses over the D.550, which is accessible via Exit K1. Exit K1, named Havalimanñ, also provides access to Adnan Menderes Airport, via the D.550.
Following Exit K1 the O-31 becomes a toll motorway after passing through Pancar Toll Plaza, which uses automated vehicle classification to recognize different types of vehicles and price them accordingly.
The next and first tolled exit on the motorway is Exit K2, named Torbalñ, which is the Torbalñ connector. The long Torbalñ connector links the O-31 to the D.550 just north of Torbalñ. Following Exit K2, the motorway continues south bypassing Torbalñ on the west. Near the village of SaÃÂlñk, is the SaÃÂlñk Rest Area, which consist of restaurants and a gas station. Exit K3, named Belevi, is the last exit within the ðzmir province. This exit connects to the D.550 to Selçuk as well as the coastal city of Kuà Âadasñ.
After Exit K3, the O-31 passes over the long Belevi viaduct and then enters the long 75th Anniversary Selatin Tunnel (), passing through the Aydñn Mountains and into Aydñn Province.
After exiting the tunnel, the Selatin Rest Area is available for northbound drivers. The motorway descends into the Greater Menderes Plain and turns east. After passing over the Kñzñlcapñnar viaducts, Exit K4, named Germencik, connects to the D.525 to Söke, as well as the D.550 to Germencik. Following the exit, the Germencik Rest Area is available to southbound drivers. After passing over the ðkizdere Creek, the tolled section ends at the Aydñn West Toll Plaza.
Right after the toll plaza is Exit K5, named Aydñn North, with the D.550 in west Aydñn. The O-31 becomes the Aydñn Beltway and runs around the south of the city. The next exit is Exit K6 with the D.550, which heads south to MuÃÂla. Up until 2016, this was the end of the motorway. Following Exit K6, is the incomplete Exit K7. Exit K7 is where the motorway continues east to Denizli and Burdur. The O-31 used to continue as the Aydñn Beltway through the next exit, Exit K71. Exit K71 connects to Mehmet Ali Tosun Boulevard and the Aydñn Airport. The route continues through Aydñn East Toll Plaza and restarts the tolled section. This section is operated by Fernas Otoyol ðà Âletmesi A.à Â., under a build-operate-transfer concession.
Just over 1 km (0.6 mi) south-east of Exit K12, O-31 enters Denizli Province. Exit K12 connects Buharkent Toll Plaza to the south and the D320 just west of the city of Buharkent to the north. There is a closed rest area near Kumluca. Exit K13 connects D320 to the Sarayköy Toll Plaza to the motorway. Exit K14 leads to the Denizli Beltway (D320/D585) and Kumkñsñk via Denizli-Aydin Highway (near D320). Exit K15 leads to the town of Pamukkale via the Pamukkale Highway. The route and tolled section of the motorway terminates at Exit K16 in Kocabaà Â, connecting the motorway with D320 in Kocabaà Â.