The reopening of the remaining lane on the westbound A27 follows the completion of the investigation at the roadside at the weekend.
The westbound entry slip road at the Adur Flyover (A283) and the north access to the airport have also reopened.
Highways England asset manager Peter Phillips said:
We would like to thank drivers for their patience during this difficult time and send our heartfelt condolences to anyone who has been affected. We have been working closely with Sussex Police and other partners to help them in their vital investigation work. Now that they have moved away from the road we have been able to repair the road as quickly as possible and now in a position to fully reopen both lanes.
A 40mph speed limit will remain in place on the westbound carriageway until the ongoing recovery work in the area has been completed.
The traffic lights at the Sussex Pad junction were substantially damaged and require replacement. In the meantime a barrier has been installed in the central reserve to prevent right hand turns from being made at the junction until repairs can be carried out. Drivers seeking to make right hand turns at the junction will be directed to continue to the next junction and return on the other carriageway.
Repairs to the traffic signals will be carried out once further assessments have been carried out to the equipment and any new parts installed. It is estimated that this could take up to 8 weeks to complete. A crossing for pedestrians, equestrians or cyclists will not be safe to provide until the lights are repaired.
The A27 had been fully closed in both directions following the disaster on Saturday 22 August. The westbound carriageway and one lane of the eastbound carriageway reopened on Sunday 30 August.
Members of the public should contact the Highways England customer contact centre on 0300 123 5000.
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