The $1.2 million repairs to the Acton Tunnel have been pushed back by three months, meaning the Parkes Way roof will have been left damaged for almost a year.
Meanwhile, the driver of the truck that carried the oversize excavator on October 20 last year will return to court on July 7.
The male driver was charged with two counts of failing to comply with dimension requirements.
A Transport Canberra and City Services spokesman said works on the westbound tunnel were "likely" to start in early September, with a tender for the work advertised on Wednesday.
Roads ACT director Tony Gill said in February the replacement of the 80 damaged tiles, each weighing 80 kilograms, was planned to be completed by the end of June.
The total estimated cost of the tunnel works remains unchanged at about $1.46 million, made up of about $1.2 million for the repair and $260,000 for the immediate Roads ACT clean-up. Both costs were covered by insurance.
The October crash caused traffic chaos, shutting the westbound tunnel for more than 50 hours, while the speed limit returned to the usual 90km/h only a month after it reopened.
Mr Gill said the decision to replace the tiles and fill in the exposed roof areas was made for aesthetic reasons and to dampen the vibrations from the general traffic.