Posted 20 December 2021
If you’ve driven up to Hotham from Harrietville lately, you could not have missed the major works being done on the Great Alpine Road by Regional Roads Victoria.
While it’s a bit annoying to have to wait for the lights to change at the worksites, it might help to know that the work is a huge investment by Regional Roads Victoria to ensure safe access to Mt Hotham – and it’s providing local jobs as well.
Funded by the Department of Transport’s Building Works Program, the work is all about stabilising the foundations of the road, which in many sections was built over a foundation of poorly prepared ground (sometimes just bulldozed trees and earth). Over time, the organic components under the road have rotted and water has found its way in, resulting in instability and creating the risk of landslips.
The work currently under way is reconstructing the road foundations, ensuring effective drainage, and therefore ensuring stability of the road long into the future.
Roads don’t like water
“Water is the enemy to roads” is a mantra you’ll hear frequently among road engineers, so drainage is critical to a road’s longevity. The Great Alpine Road has some special challenges too – there are active springs along the road, so these need to be identified and dealt with.
There is an optimum water level for the road materials, which enables optimum compaction (too dry is also not good!). This is why the work halts when it's raining - in a ‘La Nina’ weather period, this increases the risk of delays. In fact, even snow (which fell on the top work site in November) is less of a problem than rain, as it doesn’t wash away the materials that have been laid.
The drainage work done on the road prior to winter 2021 was designed to underpin the current work, by constructing culverts to ensure water is directed out from under the road.
Digging to find firm ground
At the higher site, the team could not find a solid foundation after digging down three metres so the decision was made to dig further and punch 300mm rock into the ground, followed by 150mm rock to create the required stability. 800 tonnes of rock was needed but then the site was ready for the next stage.
At that site, you might have seen black mesh being laid out on the site. This is ‘geo grid’, designed to stabilise the road materials and prevent tension cracking, as the cracks can’t penetrate the geo grid.
There are six layers of geogrid at this site, laid every 400mm, from 3 metres from the base.
Protecting the environment
Regional Roads Victoria is committed to minimising environmental impacts on all its sites. For example, where trees need to be removed environmental offsets are used to counteract the impact of the removals.
In addition, all sites have an environmental assessment prior to works starting. At the higher work site, the Alpine Tree Frog has been found in the vicinity, so footwear must be disinfected whenever stepping off the worksite into natural bushland. This helps prevent the spread of a fungus that affects the frog, which is a unique issue on this road.
All worksites need strict occupational health and safety protections, and the RRV sites are no exception, with steep drops off the sides of the sites, and heavy machinery and trucks constantly in action.
Possibly the greatest risk, though, comes from drivers who fail to follow the directions signposted at the work sites. This includes running the traffic lights (which are used when workers at not on-site) and driving too fast through the worksite. The lights are timed to allow for the slowest moving uphill traffic (cyclists) and it’s not possible to see to the end of the diversion, so travelling through against the light is extremely hazardous and drivers who do this risk a head-on collision.
Work will be completed in 2022
Work on the lower site is complete, but the top site will continue until early 2022, so we ask that everyone remains patient and enjoys watching the road be recreated to last for many more decades to come. From 23 December two-way traffic will be reinstated until around 10 January, with speed limits in place - please drive safely!
The next piece of work on the Great Alpine Road will be at Diamantina Corner, which suffered a slip on the downhill side prior to winter 2021. That work is expected to start in early 2022, and we’ll provide you with updates on that closer to the work commencing. However we can advise at this stage that there will be a lane closure for two to three months, similar to the lane closures at the current sites.