Original sentence: Cost overruns had reached about $600 million due to the delays in tunnel boring.On January 11, 2019, the Alaskan Way Viaduct will be permanently closed in preparation for the opening of the new tunnel, which will require the excavation of several buried ramps at the south portal and other road realignments.WSDOT reverted to the tunnel's original opening date of early 2019 to accommodate a longer preparation period and avoid potential work delays due to winter weather
Edited sentence: By that time the cost overrun balooned to about $600 million.In September 2018, the tunnel's opening date was pushed back to WSDOT's original plan of early 2019.On January 11, 2019, the Alaskan Way Viaduct will be permanently closed in preparation for the opening of the new tunnel, to connect the tunnel to the rest of SR 99