The gorge re-opened at the end of May after being closed on August 18 last year, when heavy rain caused a major slip.
The gorge re-opened two days before another massive slip again closed the roadway.
"The gorge has been fully open for some time but there has been a range of niggly jobs that we needed to get done before we could pack up. This is the last of those jobs.
"When we build a new road, we have to come back a few weeks later and lay down a second layer of asphalt to ensure it stays tough and durable, so that's what this final task is. Once the job's done, the contractors will be packing up their site office and having a well-earned cuppa."
Mr McGonigal said the site would be controlled by stop-go operation and speed restrictions this week.
Work crews also would install permanent signs and edge marker posts, as well as carry out general clean-up work.
Mr McGonigal said the NZTA would continue to work with the Tararua District Council and Palmerston North City Council over the rehabilitation and upgrade of the Saddle Rd.