The number of engineering challenges on the £6bn Lower Thames Crossing (LTC) will make it one of the most complex development consent orders (DCO) ever submitted, its project director has said.
Speaking at New Civil Engineer’s Tunnelling Festival, Highways England LTC project director Tim Jones said the number and size of the civil engineering challenges to be overcome are substantial.
He added that environmental challenges, including the whale currently located in the Thames, are among additional hurdles to overcome.
“The preparation for our DCO, a very large planning application, is going to take quite some time to do,” he said. “The reason for that is because it might be one of the most complex DCOs the authority has ever received.”
The multi-billion-pound LTC project will create a new, 23km long, three-lane dual carriageway connecting the M2 near Rochester in Kent with the M25 in Essex between North and South Ockenden and will involve building a new 3.8km long, 16m diameter tunnel under the Thames.
However, Jones said providing the 60MW required to power the tunnel boring machines, would be a substantial undertaking and Highways England was working with the National Grid to provide the connection.
One of the biggest challenges he said the project would face was around air quality and how the impact on the local community could be managed. He said although research had shown that in 10 years’ time, 50% of people would be using electric vehicles, this could not be used to prove its case and good traffic modelling was “essential to make sure the project moves along successfully”.
The project is just about to launch a significant ground investigation survey as he said ground conditions along the length of the new road varied significantly.
“There’s nothing that I’m doing on the LTC that does not touch some form of environmental legislation,” he said. “I even have a whale swimming in the Thames which is swimming across the alignment so we can’t get equipment down to find out about the chalk aquifer. Let alone other ecology issues.”
Benny the beluga whale has been located in the Thames since September. The Port of London Authority is monitoring its condition.
“Made ground surrounding the new tunnel will also be a challenge,” Jones added. “Both Crossrail and Tideway have used the area as a spoil heap to dispose of tunnelling waste which has left varying “levels of contamination across the site.”
“There is also a Victorian land fill site which has been capped off, so as soon as you start breaking ground, the combination of risks and managing that is going got be a project in its own right,” he said.
Sensitivity around protected areas for migrating birds on both sides of the river, together with an area of outstanding natural beauty, a site of special scientific interest (SSSI), an ancient woodland and going through the metropolitan green belt would also be an issue he said.
To the south of the project, he said complications with the A2 M2 junction, the High Speed 1 line and the challenge of keeping the existing eight lane motorway open during construction of the project would be “an extremely challenging piece of civil engineering”. To the north, he said the intersection with the A13 was complicated by the need to keep the “critical” A1089 route to the Port of Tilbury open.
Along the alignment of the new road, he said around 20 pylons would also have to be moved which was an added complication to the road’s construction. How the road will be built has also yet to be decided Jones said.
“The contract interfaces are going to enormous so working out what the right combination of packages are, we’re working that through at the moment,” he added.
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