Where’s the world’s longest road tunnel?
From tunnels deep underground to sky-high mountain passes, civil engineers and builders have created some truly impressive roads.
We look at some of the world’s most extreme roads and see how they stack up against Australia’s best.
Longest road tunnel
World
Fiord-riddled Norway is home to the world’s longest road tunnel (pictured above). The Lærdal Tunnel stretches 24.5km from Aurland to Lærdal and provides a ferry-free link from the capital Oslo to the stunning coastal city of Bergen.
To keep drivers alert, cavernous sections every 6km are splashed with a dazzling coloured light display.
Australia
Opened in 2023, the M8-M4 link tunnel connecting the M8 and M4 tunnels, on Sydney’s WestConnex road network, forms a total length of 22km, making it the longest tunnel in Australia.
Highest sealed road
World
Climbing to a height of 5800m, the Umling La Pass in India is the highest sealed road in the world, even higher than Mount Everest base camp at 5364m.
The 54km-long road connects the villages of Chisumle and Demchok, near the Chinese border. The route winds through a barren landscape beneath the snow-capped Himalayas, passing through some of the world’s most dramatic scenery.
In addition to typical mountain pass advice about snow and winding roads, authorities discourage people with respiratory or heart issues from risking the trip. Even sturdy souls should acclimatise for a few days at lower altitudes before heading off along the world’s highest sealed road.
Deep snow closes the road in winter, when temperatures can plummet to a crisp -40⁰C.
Due to the territorial sensitivity of the region, foreigners must organise a Protected Area Permit through a registered Indian travel agency. Travelling with an organised motorcycle tour is a popular way to reach the dizzying heights of Umling La.
Australia
The 308km-long Great Alpine Road is the highest sealed road in Australia, connecting Wangaratta on the Hume Highway with Bairnsdale in Victoria’s Gippsland Lakes region.
Breathtakingly scenic, the route passes through Victorian snow country, climbing to 1845m near Mount Hotham Resort.
There are narrow and steep sections en route, particularly between Harrietville and Mount Hotham. Ice and snow are common in winter and snow chains must be carried into the Mount Hotham Resort area during the declared winter season, which usually runs from the King’s Birthday long weekend to the first weekend in October.
Although a permit is needed to enter Mount Hotham Resort during the ski season, it isn’t required for motorists just passing the resort on the Great Alpine Road.
Longest (continuous) road bridge over water
World
At 38.4km long, Lake Pontchartrain Causeway in Louisiana, USA, is the world’s longest continuous road bridge over water.
Two parallel bridges – one for each traffic direction – connect Metairie on the lake’s southern shore to Mandeville on the north shore, both of which are part of greater New Orleans.
The first of the two-lane bridges was completed in 1956 and the second in 1969, cutting commuting time from the north shore to central New Orleans by about 30 minutes. Under normal conditions, the crossing takes just under half an hour.
If you’ve had enough after the first few kilometres, there are several turnaround spots (crossovers) along the way.
Higher points en route allow boats to pass beneath the structure, plus there’s a drawbridge for taller vessels.
The ‘continuous’ classification precludes two longer road bridges in China. The 41.6km-long Jiaozhou Bay Bridge in Qingdao includes a tunnel and sections over land, while the 55km-long Hong Kong-Zhuhai-Macau Bridge is interrupted by a tunnel between bridge sections.
This means the longest continuous segments of these bridges are shorter than Lake Pontchartrain Causeway.
Guinness World Records have popped these Chinese engineering marvels into the ‘longest bridge over water (aggregate length)’ category.
Australia
At 3.2km, the Macleay Valley Bridge over the Macleay River and its floodplain near Kempsey, NSW, is considered the longest bridge over water in Australia, but when the river’s not flooded, most of the bridge spans dry land.
The longest continuous bridges over permanent water – albeit tidal – are the twin, 2.74km-long parallel Houghton Highway and Ted Smout Memorial bridges across Bramble Bay, north of Brisbane.
For all its grandeur, Sydney Harbour Bridge is the fifth longest road bridge in Australia.
Steepest street
World
Steep-road enthusiasts would no doubt be aware of the Baldwin Street vs Ffordd (Street) Pen Llech dispute.
Baldwin Street in Dunedin, New Zealand, held the Guinness World Records’ steepest road gong until June 2019, when it was pipped for the prize by Ffordd Pen Llech in Harlech, Wales.
The Baldwin Street representatives then challenged the Harlech crowd by claiming Guinness should take into consideration the different shapes of streets. They successfully argued that whether a street is straight or curved can affect the result depending on which side of the road is measured. Baldwin Street is straight and Ffordd Pen Llech is narrow and winding.
Taking this on board, Guinness decided steepness would be measured at a road’s centreline, and consequently declared, “Baldwin Street has the steeper gradient of 34.8 per cent, compared to Ffordd Pen Llech’s gradient of 28.6 per cent.”
The Kiwis reclaimed the title in 2020.
To preserve harmonious international relations, Baldwin Street’s Toby Stoff said, “The issue of gradient was technical in nature only. There was no bad feeling toward the people of Harlech.
“I had the great joy of visiting last November. It is a wonderful heritage town full of friendly people.”
Australia
There’s no official list of Australia’s steepest streets, but there seems to be a lot of online fingers pointing towards Gower Street in Toowong, Brisbane, with a 31 per cent gradient.