Winvic’s steel anchors SEGRO’s ‘inland port’

 

The steel frame of the fulfilment centre on plot one

 

The vast East Midlands Gateway logistics hub, which will comprise three million square foot of warehouse space when complete, is being built with over 13,000 tonnes of structural steel. Will Mann reports.

One way to understand the scale of SEGRO Logistics Park, East Midlands Gateway, is through its description as an “inland port”. At the heart of the UK distribution network, 13 miles south-west of Nottingham, it has been categorised as a Nationally Significant Infrastructure Project (NSIP) due to the planning consent required by the Planning Inspectorate.

The development spans 285ha and incorporates a 20ha strategic rail freight interchange (SRFI) which will include the only terminal capable of handling freight trains direct from Europe via Eurotunnel. Planning consent has been given for up to six million sq ft of logistics accommodation with container storage and HGV parking.

Main contractor Winvic will have completed the construction of almost three million sq ft of modern warehousing, plus office space, across four plots by the end of April. As is typical on industrial projects, structural steel has been central across the whole development – with a staggering 13,500 tonnes used on the four plots built as part of the scheme.

“Speed and flexibility are the main drivers for using a steel frame; in just two to three months these enormous frames have been erected,” says Dave Platt, one of Winvic’s project managers on the scheme. “It would make little sense for a warehouse to be built with a concrete frame.”

Design manager Jason Etienne adds: “With the height, spans and bays, plus the way the buildings are used, concrete isn’t an option. The cost and programme savings are enormous in comparison.”

Winvic has worked with its regular steel fabricators Severfield and Caunton on the project. The main contractor has used five project managers across the different plots, with over 100 years of experience between them, meeting regularly with the steelwork contractors to handle any programme conflicts.

The multi-span portal frame design  of the structures aims to maximise internal space, with “valley columns” missing every two bays, explains Etienne.

“The brief was to use a ‘hit and double miss’ approach, meaning every two columns were removed from the frame’s design, creating more functional space inside,” he says.

“Due to the location, the wind loadings are quite high, so we designed huge bases for the valley columns – 7m x 3m – which were installed 3m deep,” Etienne adds.

Plot one is the largest of the four. This 1.3 million sq ft fulfilment centre, almost 300m long by 200m across, will use around 7,500 tonnes of steel. The structural grid is typically 32m x 8m, then 16m x 8m on the two mezzanine levels. An added complication with the mezzanine structure is that it had to be able to be removed in the future.

 

Erection of the high bay steel on plot two

 

Frank Hayes, Winvic’s project manager on this plot, says: “Our remit was to create a building with a two-storey mezzanine, but where the mezzanines could be removed if the occupant ever left the premises and the space could be used differently.

“This meant every opening for the main construction and fit out had to be carefully coordinated – we couldn’t just drill a hole later down the line.”

To accommodate the mezzanine removal, the foundations have been beefed up with concrete bases at intervals around the building – the largest is 605 cu m and was poured in one day – as has the structure’s bracing, which is located in the stair towers.

A BIM model was used to design the complexities of the separate mezzanine structure, Hayes adds. 

“To facilitate the end user’s state-of-the-art robotics system, it was vital that the concrete floors were completely level,” he continues. “We used a specialist screeder to lay the mezzanine floors, but despite all the calculations we could not be 100% sure how the weight of the machine would affect the levelling process; the concrete had to be strong enough but still perfectly malleable. It feels a little like we achieved the impossible but we have the flattest floors in Europe, if not the world, here.

“These unusual specifications necessitated a process of continuous design, assessment and refinement,” Hayes says. “Even as the outer frame, mezzanine steels and concrete floors were being constructed, we were analysing and perfecting as we went.”

 

The giant fulfilment centre on plot one, with the steelwork partially clad

 

The whole frame was put up in just 12 weeks – with the mezzanine installation beginning four weeks in – which is the fastest Winvic have ever erected a warehouse of such size and complexity, according to Hayes.

Plot two is a 638,000 sq ft warehouse, and is the tallest of the four buildings, with the unusually high bay rising to 35m. The warehouse is 250m long by 226m wide, includes a 40,000 sq ft mezzanine, and uses 3,300 tonnes of steel. The grid is typically 35m x 8m, rising to 42m x 8m for the high bay.

“This plot is the tallest industrial facility that Winvic has built,” Dave Platt, Winvic’s project manager on plot two, explains. “A 35m high bay is unusual – the majority of industrial warehouses reach the 20m mark.”

This plot also features the biggest span on the whole development – some 44m – which was too long to be transported in one spice so had to be spliced together on site.

“The high bay also caused programme complexities, for example, calculating the time it takes to go up to 35m and back down again in a cherry picker,” Platt notes. “Unfortunately, we can’t just order in a 50m cherry picker for the following day – there might be one available in Holland if you’re lucky – so meticulous planning and execution was required to create this huge steel frame.”

 

Aerial of the site prior to steel erection on plot four (foreground). East Midlands Airport is to the right

 

Plot three is an 898,000 sq ft distribution centre, where the five-span portal frame is 260m in length by 189m across. There are three bespoke mezzanine levels, supporting automated conveyor systems, and part of the fit-out programme will run alongside the construction. The structure, which includes a mezzanine bridge link, uses 2,160 tonnes of hot and cold rolled steel, with the portal spans up to 37.6m.

The fourth plot is the smallest structure, at 196,000 sq ft, with a 163,000 sq ft single-storey production unit. It also includes a 33,000 sq ft office area. The building, 216.4m long by 70m across, includes portal spans up to 34.8m and uses 924 tonnes of hot and cold rolled steel.

The structure includes a steel cantilever bridge link to the main office and an external cantilevered canopy, which allows vehicles to be side loaded with forklift trucks.

As well as its vast scale, the project faced other logistical challenges. East Midlands Airport’s runway is just 150m from the site boundary so crane use often required special permissions, particularly on the 35m bay of plot two. “Not only were there strict height restrictions, but the majority of crane activity had to be sanctioned by the airport a month in advance,” explains Platt.

Cranes used ranged in capacity from 35 to 200 tonnes, with plot one – due to its size – using tracked cranes inside the structure.

Prior to steel erection, Winvic carried out a vast earthmoving and site preparation exercise, which started in early 2017. The muckshift involved some six million cu m of material, while ground remediation avoided the need to excavate and replace a further 250,000 cu m.

Moisture was squeezed from the soil over an area of 32,000 sq m and compacted under high pressure to ensure the ground was robust enough to construct upon. The settlement differential risk was eliminated after 12 weeks and a 300mm concrete slab was laid as a base for heavy plant to begin work.

Construction of all four plots is scheduled to finish this month, with fit-out work running through the year and final completion due in September.