ONE SHOT: This is how to build a bridge in 3 days
HOW do you demolish an entire rail bridge and replace it with a 320-tonne version in three days?
For the Grafton Bridge project, one meticulously planned step at a time.
From 2am Saturday morning, the entire North Coast rail line will shut down, and a brand new rail bridge will be installed at Pound St just in time for the rail line to reopen at 2am on Tuesday.
"We only get one shot at it," senior project manager Grafton Bridge Greg Nash said.
"It will happen rain, hail or shine. There are no other windows this big to do the work."
Once the last train rattles through at 2am Saturday, the team will kick into action at 2.15am, removing the rails, sleepers and ballast.
By around 6am, the demolition of the actual bridge section will begin, taking most of Saturday.
By Saturday night, works on preparing foundations and beams for the bridge will begin to be ready by Sunday morning.
"Sunday morning we'll do the lift, putting the bridge up," Mr Nash said.
"It's a 325-tonne lift with a 750-tonne crane, and that will take most of Sunday."
Once the bridge is lifted, the other short spans and approach spans as well as transition slabs will be installed.
Finally, the finishing touches such as the waterproof membrane, joints, ballast, and the rail lane will be completed in time for the next train to come through again at 2am Tuesday morning.
"It's a real milestone for us, as once we get the bridge up we can complete the approach roadworks up to the new bridge," Mr Nash said.
"The new bridge is 42m wide and will have 5.3m of continuous clearance under the span. The old one had about 4m of clearance, and we need 5.3 to run the semis and legal loads onto the bridge.
"This all becomes the Summerland Way."
Mr Nash said there would be around 30-40 people constantly on site for the 72 hours, including various sub-contractors for rail work, waterproofing, bearings and other jobs, all working to a strict schedule.
"This has taken two years worth of planning," he said. "It's a major operation, and we've got it down to an hour-by-hour plan of how we're doing it."
The crew performed a test lift of the bridge span on Thursday morning, lifting the truss to confirm everything is working as planned, and installing bearings to ensure its readiness.
"We're trying to put all these things in place to make the process go as seamlessly as it can, and foresee all the issues," Mr Nash said.
"There will be issues, but we should be able to foresee all of them."
The historic mile marker on the existing rail bridge, which is one the last remaining on the line between Sydney and Brisbane, will be removed and preserved during the work.
The marker identifies the 433 mile distance to Sydney Central, and will be handed over to the Australian Rail Track Corporation to be preserved, hopefully to then be reinstated on the new rail bridge.
Mr Nash said the Grafton Bridge build was progressing well, with work to be finished on pier five in the next few weeks.
"Then we'll move onto pier six and seven, which this crane will move down to the river for, as it can reach further out," he said.