UPDATE: Megalong Road has reopened to light vehicle traffic.
The breakthrough on Friday, April 19 follows a major landslide caused by heavy rain that forced a two-week closure on the only sealed public access road into the valley.
Blue Mountains Mayor Mark Greenhill said council had been working tirelessly to get the road open since the landslip occurred.
"The Megalong Valley is a special place which is a key tourism destination in the Blue Mountains. Getting access back into the valley is our priority, for the sake of the local economy, along with supporting our community," he said.
"I would like to thank the State and Federal Governments for their fantastic support."
Council contractors, following NSW Public Works and geotechnical advice, used shotcrete to stabilise the site and enable the use of large soil nails and sheet piles to build the temporary one-lane access road.
Federal Member for Macquarie Susan Templeman said "getting to this point took a phenomenal effort from all levels of government and the contractors on the ground".
"To have this road open to light traffic again only 14 days after it collapsed is a testament to everyone involved and I thank them all for their hard work. While a permanent solution will take some time, I know many residents will be breathing a sigh of relief, and the work will continue on a long-term plan for a reliable road," she said.
Access across the landslide site is one lane only, with a 7.5 tonne load limit while works continue to restore the road.
Traffic controls will be in place, including traffic escorts and a 10km/hour speed limit past the slip. Motorists are advised to expect delays.
Campgrounds in the Megalong Valley, including Old Ford Reserve, Nellies Glen and Dunphys Park remain closed.
APRIL 19 9AM: There are hopes that Megalong Road, the only public route into the Megalong Valley, will be reopened later today.
Workers have toiled valiantly since a landslip took away most of the road on Friday, April 5.
By April 11, a pedestrian path had been created and a shuttle bus service set up to take residents from the site up to Blackheath.
The mayor, Mark Greenhill, posted on Thursday (April 18) that he anticipates the road could be open to one lane of traffic today.
"Great news," he wrote on Facebook. "We are continuing to finalise work to reopen one lane of Megalong Road to light traffic including visitors. At this stage it is anticipated that the road could open tomorrow, however we will confirm the opening time as we know more. There is always scope for something to impact that time frame but, right now, we are looking good for tomorrow."
Cr Greenhill added he was very proud of the work done by council's "amazing staff and contractors".
Since the road closure, regular helicopter food drops have been delivered to residents, through a click and collect arrangement with Coles, as well as deliveries of livestock feed and bales of hay.
And waste has being taken out by air, although residents have been asked to compost or feed to chickens kitchen scraps and to keep plastic and bottles until road transport is restored.