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The under cover delivery of the new King's Cross

Meeting key milestone dates was the secret to completing the Northern Ticket Hall on time, but that could only be achieved if everyone pulled together.

The Northern Ticket Hall and its associated tunnels did not just present the delivery team with an engineering challenge, but also a programming challenge. Right from the start time was tight: London Underground (LU) had contracted with the Department for Transport (DfT) to complete Phase 2 by 2010, but a redesign just before construction began put even more pressure on the programme.

Building on good relationships developed on Phase 1, LU and the ABBT project management JV adopted a collaborative approach that eventually included both the contractor and the DfT. It paid off, when the scheme came in on time and within the agreed target price.

Phase 2 takes in the Northern Ticket Hall and more than 300m of tunnels. Detailed design began in 2002.

“In 2004 the government called a halt to the works for a ministerial review, because Network Rail wanted to extend its concourse to the west” explains LU King’s Cross project sponsor Mike Crabtree.

“We didn’t have time for a minimum overlap between the heavy civil engineering and building and fit-out”

Iain Wilson, Balfour Beatty

“Our Northern Ticket Hall had to be redesigned to accommodate that new concourse over the top. Phase 2 was reactivated in 2005, and at that point the works became part of the deliverables for the Olympics,” he continued.

Construction contracts were let to a JV of Morgan Est and Beton & Monierbau for the tunnelling, and to Balfour Beatty for the ticket hall construction.

This created the interesting situation where Balfour Beatty Management (the main player in the ABBT JV) was responsible for delivering a project where its sister company was the main contractor.

In reactivating the project the government set a maximum combined price for both the LU and Network Rail schemes, which meant revisiting the ticket hall design and trying to find efficiencies.

Before the completion date could be reached there were some critical interim stages. One was that the ticket hall would be operational by the end of November 2009, to coincide with the start of high speed domestic services between St Pancras and Kent.

King's Cross

Materials were delivered through openings in the concrete roof

The other was to give Network Rail a clean ground slab for its new western concourse development by September 2008.

This slab is, in effect, the roof of the Northern Ticket Hall. Closing the slab with over a year of the project still to run took away Balfour Beatty’s main access route for materials.

Designer Arup set contractor Balfour Beatty a very strict sequence of digging and propping to form the excavation for the new structure. From ground level to -1 excavation was done from the surface, and then the slab was cast on the ground, leaving openings to get muck out.

Excavation for the next level continued beneath this ground slab, and a second slab, at level -2, was cast at the end of 2007.

Excavation for the main ticket hall down to level -4 then began in January 2008, with the excavation supported by heavy steel tubular props while concrete walls were built.

“The job was challenging but would have been a lot more challenging if we hadn’t got that integrated approach”

Ben Dunlop, Atkins

“In our original programme there would have been be a minimum overlap between the heavy civil engineering followed by the building and M&E fit-out,” explains Balfour Beatty operations director Iain Wilson. “In point of fact we didn’t have time to do that.”

One of the critical path activities was getting the main banks of escalators built and commissioned. In addition to the visible elements escalators require a lot of support that is not seen from above, including large steel trusses, all of which had to be brought into the ticket hall box before the slab was sealed up.

“We had to deliver the escalator trusses before we had finished the excavation at level -4,” recalls Wilson. The trusses were stored inside the congested excavation until they were needed.

“We wouldn’t have chosen to deliver those until we finished the civil works, because they took up a large part of our working area, but it allowed us to close up those openings and hand over the slab to Network Rail,” says Wilson.

The logistics of having both civils and finishing trades working inside the congested excavation at the same time could have proved tricky, but Balfour Beatty attempted to ensure all the subcontractors knew where they, and their materials supervisors, were supposed to be at all times.

King's Cross underground

300m, of new tunnels were excavated and fitted out

Subcontractors were asked to wear different coloured hard hats, so they could be clearly identified and Balfour Beatty took charge of all material deliveries and waste handling. Installing the escalators was not the only major critical path item.

“The communications and fire systems and the station management systems here are really complicated, and getting those commissioned and working at the end of the day became most critical,” says LU programme manager Graham Sims.

Sign-off protocols and procedures at LU can be challenging, but at King’s Cross the paths were smoothed by the close working relationships. “Since the box has been finished the required rate of progress has been remarkable,” says Balfour Beatty Management operations director Elwyn Griffiths.

“It certainly couldn’t have happened if we hadn’t had Graham’s [Sims] team integrated with us. And that integration wouldn’t have happened unless all sides were committed to that end goal.”

Hitting the September 2008 deadline for handing over the ground slab “gave everyone the confidence that the work was heading in the right direction,” says Wilson. “It was a great motivator for the team: if we can hit that date we can hit the end date.”

“If we had delivered it in any other way we wouldn’t have delivered on time”

David James, Balfour Beatty managing director

It also sent an important signal to the project’s financial backer − the government − that the scheme would not be delayed. “When we set those targets the first major test was the 1 September 2008 date,” says LU head of stations upgrade programme Andy Eastaugh.

“Nobody outside the project team thought that was going to be achieved, but for us it was a matter of pride. It was a good test of everybody from the Department [for Transport] down to the suppliers.”

But, as Eastaugh says, it “wasn’t a foregone conclusion” that the team would hit that first milestone. The Northern Ticket Hall box went through a lot of redesign once Network Rail announced its improvement plans for King’s Cross, to integrate the two schemes as much as possible and make efficiency savings.

The main escalator box was moved from the east side of the ticket hall to the west, resulting in a major change to passenger flows around the ticket hall, and a new location was found for the main ventilation shaft from the Tube station.

King's Cross workers

Site workers use the escalator to watch a safety presentation

“All of these issues and redesigns and interfaces with Network Rail delayed the start of getting on with those works,” recalls LU King’s Cross sponsor Mike Crabtree.

Under traditional contractual arrangements that delay could have been enough to push back the completion date by quite a few months.

But rather than square up over claims for extension of time, LU, ABBT and BBCEL took a collaborative approach, agreed that it was best for all parties if the end date was achieved, and negotiated a deal that incentivised that result.

“We agreed what the cost to make that date would be,” says Wilson. “Having made that commitment, and showed the client what he wanted to see, that cut out all the contractual nonsense.”

Collaboration

A collaborative approach between the main parties had started during Phase 1, but became a fundamental part of the way Phase 2 was managed.

LU, ABBT and the contractor were all co-located, along with the DfT’s representative, MPG, a joint venture of Mott MacDonald, Parsons Brinckerhoff and Gibb.

“In Phase 1 MPG were more there to police, audit and challenge,” says Eastaugh. “But as we moved out of Phase 1 and into Phase 2 there was a conscious effort to work in a more collaborative way.”

“If we had delivered it in any other way we wouldn’t have delivered on time,” says Balfour Beatty Management managing director David James.

“With the collaboration there was a good mix of thinking that meant the solutions we found were very often generated by people you wouldn’t expect. We worked it out by contractors not being contractors and consultants not being consultants.”

Atkins regional manager Ben Dunlop adds: “It’s been a challenging job but it would have been a lot more challenging if we hadn’t got that integrated approach.”

 

Complete: Northern ticket hall

The new ticket hall takes up the area of a football pitch and consists of four basement levels. It has been built in a very tight space between the listed “Western range” of King’s Cross station and the Great Northern Hotel.

The entire structure has been built inside a contiguous bored piled “box”, with piles reaching depths of 37m in places. It has a series of concourses, the first, at 5m below ground, giving direct access to the new High Speed

One and domestic terminal at St Pancras. From here passengers can walk through tunnels to the extended main ticket hall or to King’s Cross mainline station.

A large bank of escalators takes passengers down from this level to the main concourse 20m below ground. Here new pedestrian tunnels give step-free access to the Victoria and Piccadilly lines, with two banks of escalators plunging still deeper underground to take passengers down to the Northern and Piccadilly line.

Key facts

  • 41,300m³ of excavation
  • 11,900m³ of structural concrete
  • 1,800t of structural steel
  • 10 new escalators
  • 5 new passenger lifts
  • Fit out of 300m of new tunnels
  • Two periods of 1,000,000 man-hours without reportable accident

 

Tunnels

Both phases of the King’s Cross station improvement involved an element of tunnelling, but the largest chunk fell within Phase 2, when new pedestrian routes were built to link the three ticket halls and take passengers from new concourses to the tube lines.

“Tunnelling was a major concern,” says Balfour Beatty former tunnelling operations director John Hester. “We were below a listed building with big trains and we were going to build tunnels only 7m below the track and 11m in diameter. Failure was not an option.”

The team’s approach was to “de-risk” the tunnelling activities as much as possible, redesigning where necessary to find safe ways of doing the work that would prevent any chance of settlement.

“You can’t put an estimate on the cost of having a train drop six feet into a tunnel,” says Hester. “We could not allow anything to go wrong underneath King’s Cross.”

 

Balfour Beatty − project manager and contractor

With Balfour Beatty Management staff making up a large proportion of the ABBT project management team, eyebrows were bound to be raised when Balfour Beatty won the contract to build the Northern Ticket Hall.

“Phase 2 was competitively tendered,” explains Balfour Beatty Management commercial director Paul Pethica. “Balfour Beatty won the contract for the ticket hall and Morgan Est got the tunnels.”

Before awarding the contract ABBT had to get London Underground’s approval to use one of its group companies.

“I think it was a good test for us , because if we were found to transgress in our role we would have failed,” says Balfour Beatty Management managing director David James. “I suspect Iain’s team would say we were over-zealous.”

‘Iain is Balfour Beatty Major Projects operations director Iain Wilson, who says: “I’ve been with Balfour Beatty for 28 years, so there were already established working relationships.”

Although the two Balfour Beatty group companies maintained a professional distance, the collaborative approach eventually led to people from the ABBT project management team working within the contractor’s organisation to help with delivery.

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