Tunnel vision: At least 13 kilometres are expected to be in a continuous tunnel, from Strathfield to St Peters. Photo: Jim Rice
Sydney motorists will be driving along some of the longest urban road tunnels in the world, raising questions about how drivers will cope with the long stretches underground and about what happens when accidents occur.
The concerns emerge as new details come to light about the process of planning the 33 kilometre WestConnex motorway. At least 13 kilometres are expected to be in a continuous tunnel, from Strathfield to St Peters.
At nine kilometres, the NorthConnex motorway to be built between the M1 and M2 in northern Sydney will also be more than twice as long as any other in Sydney.
''These are at the top table,'' said Arnold Dix, a leading tunnel safety expert who is consulting on both projects.
''This is not Australia building some tunnel like everybody else builds. This is the frontier. This is as challenging and as technically demanding as any of the main projects in the world at the moment.''
Even the NRMA, which is a strong supporter of the motorway projects, is arguing that the new tunnels need to be designed differently.
In a presentation to a road safety conference last month, the NRMA's senior policy adviser on roads, Mark Wolstenholme, said tunnels were monotonous for drivers and ''fatigue or tiredness in drivers in tunnels is more prevalent''. The insides of tunnels needed to be made interesting for drivers to look at, he said.
Mr Wolstenholme said the surface connections of the tunnels needed to be better planned because, if there was a big accident, the entire tunnel would need to be closed.
This meant that, for the WestConnex project, traffic would need to return to the road surface and planned bus lanes on Parramatta Road would need to be opened up to car traffic, Mr Wolstenholme said.
The question of the tunnel length emerged for WestConnex officials relatively late in the piece. The project director for the motorway, Paul Goldsmith, emailed advisers in May to request a position paper about long tunnels.
''We've assumed to a large extent that existing Sydney tunnels provide precedents to follow,'' he wrote.
He was told by a consultant, Steve Messenger, that there was in fact no precedent in the world.