The Buca Onat Tunnel () is the name of the tunnel, currently under construction, in ðzmir, Turkey. The tunnel is part of a express route that will connect the ðzmir Coach Terminal, in Bornova, to central Konak, via the Konak Tunnel. Once completed, the tunnel will become the longest tunnel in the ðzmir Province and the 14th longest in Turkey. Work began on 12 March 2018 and the estimated construction cost is âº184 million.