Meadowhall is the worst place to build an HS2 station because the rock beneath it is ‘mush’, according to a top engineer.
The proposed high speed rail line follows a three-mile fault of fractured rock, posing a huge - and as yet uncosted - engineering challenge, says Adrian Millward, former assistant chief engineer at Sheffield City Council.
HS2 Ltd’s plans for a colossal concrete viaduct - six tracks wide and two miles long - would be severely hampered by the unstable ground, while maintenance costs could dwarf the huge sums needed to build it, he believes.
He added: “If I was to pick a spot not to build a station, that would be it - and HS2 is bang on top of it. You could not build in a worse place.
“The rock is shattered, flooded and connected to old mine workings, forming what is essentially an underground reservoir. Drill into it and it turns to mush.
“I think they have underestimated the difficulty of building a new viaduct at Tinsley and I don’t think they’ve taken the cost into account.”
Mr Millward worked for Sheffield City Council between 1980 and 1999. He also spent three years as head of mining and subsidence at Barnsley Council.
He has first-hand knowledge of the area, his team built a 20ft sewer between nearby Blackburn Meadows and the city centre in the 1970s. The project was delayed by a year due to the difficulty of crossing the north-south fault.
“It was like tunnelling through sand with water through it. The cement grout would wash away.”
Ultimately, liquid nitrogen was used to freeze a 650ft wide swathe of ground.
Tinsley Viaduct, which carries the M1 and runs parallel to the proposed HS2 route, has cost 16 times more to maintain than to build, Mr Millward says.
“It’s not that the city centre is expensive, it’s the cost of building at Meadowhall. The motorway viaduct is made of steel and flexes, it can move with the ground.
“But with trains running at 250mph, the high speed viaduct has got to be extremely rigid for two-and-half miles. As we have seen, the cost of maintaining it can be much more than actually building it.
“And I’m concerned at plans for a ‘station in the sky’ simply from a safety or security point of view. It would be very exposed and vulnerable, what if there was a terrorist incident?”
Mr Millward has Coal Authority maps which show the route north of Meadowhall is riddled with mine workings. HS2 plans show a one mile tunnel through this section.
“The ground up to Hoyland is awash with old workings. It’s full of holes which are full of water. The geology along the whole length of the route is a problem - has HS2 taken it into account?
“The city centre, in contrast, is built on solid rock. That’s why the city is where it is and where they built the castle and Victoria station.
“I think the construction costs of both routes might be about the same.
“But if you take into account the economic benefits of a city centre station and links to HS3 it’s a no brainer,” he added.
Edward Highfield, director of Creative Sheffield, the city council’s business development department, said: “There is nobody in the country better qualified or experienced to comment on what HS2 will face - and the warnings are stark. All the evidence suggests you couldn’t pick a more complicated and therefore expensive place to build a railway – let alone one on a viaduct with a station on stilts. There is growing concern HS2 is failing to take proper account of the evidence.”
An HS2 Ltd spokesman said: “A final decision on the Phase 2 route and station locations, which will be fully costed and within budget, will be taken by the Secretary of State for Transport later this year.
“We continue to welcome information about technical, environmental and economic matters from all the relevant city regions.”
WHY POLITICAL TIMETABLE IS DRIVING CONSTRUCTION ISSUE
“I stood the route engineer on site and he couldn’t explain why it goes through there.”
Adrian Millward, former chief engineer at Sheffield City Council, briefed HS2 staff about geological problems in the Meadowhall area in a meeting with Sheffield MP Clive Betts and local councillors in October 2014.
But he believes other priorities are at play.
“I said subsidence is a significant additional risk at Meadowhall. They just said they’d throw more budget at it, I was appalled.
“The political timetable is driving this, they are desperate to get parliamentary approval for the route.
“That means there’s a fundamental problem - they decide on the line before doing detailed investigations. So they haven’t done the work.
“With every other engineering project you do it the other way round.”
History has a lesson in the form of Tinsley Viaduct.
Mr Millward added: “The original design was contrary to the advice of the county engineer, who refused to approve it as ‘not fit for purpose’.
“Over-ruled by the Department for Transport, the structure had to be subject to strengthening works that cost 16 times the original construction bill - and it still only carries two lanes of motorway traffic instead of three.”
BUSINESS BOSS URGES REVIEW OF PROPOSED HS2 STATION
The potential difficulties of building an HS2 station at Meadowhall mean a review of the locations is more important than ever, according to Sheffield Chamber chief Richard Wright.
He said: “I am no geologist and no construction expert but this new information would raise even more uncertainty around the proposed current route through Meadowhall.
“We have so much new information around jobs, cost, geology and HS3 that it would be criminal not to re-assess the station, as a region, and assure ourselves that we are doing the right thing. It’s not about us - it’s for our children and grandchildren and we owe them that.”
Mr Wright has drawn up five principles to help decide on a location, including economic impact, delivering and integrating with HS3, aligning with the region’s economic plan and ticket sales.
ECONOMIC ADVANTAGE OF CITY CENTRE
A decision on where to build the HS2 station will be made this year.
Government choice is Meadowhall, but The Star and hundreds of public and private sector organisations believe it should be in the city centre.
HS2 Ltd’s own figures show it would create 6,500 more jobs and 1,000 extra homes, while its advisers, Genecon, say it would pump an extra £5bn into the economy over 25 years.
HS3, or Northern Powerhouse Rail, is a plan for half-hour journeys between the centres of Leeds, Sheffield and Manchester.
HS2 could form the eastern leg of HS3 between Leeds and Sheffield – but only if the stations are in both city centres. If the Sheffield station is four miles away at Meadowhall, then what?