SSDA 2019 A W A R D
Located within the King’s Cross
said to be one of Europe’s largest
regeneration schemes, the Coal
Drops Yard is London’s latest world-class
Two long brick and cast iron Victorian
buildings, known as East and West Coal
Drops, built in the 1850s for receiving and
sorting coal as it arrived in London by train,
form the scheme.
The buildings, which are approximately
150m-long and 120m-long respectively,
sit side-by-side while splaying outwards
in a southerly direction. A new roof
structure straddles the area between the two
structures, towards the northern end where
the gap is about 30m-wide.
Numerous constraints, particularly the
size of the building footprints led the project
team, directed by Heatherwick Studio, to
reach a design solution whereby the two
structures became linked at roof level, by
creating a new floor that ‘floated’ over the
central yard space below – creating an ideal
location for an anchor unit.
While English Heritage and Camden
Council gave their permission to link
the roofs via a bridge like structure, they
requested to connect the roof in a way which
maintained the idea that the East and West
Coal Drops were two separate entities.
The request lead to the unusual
architectural design of the ‘kissing point’ in
which the two inner roofs stretch toward one
another and delicately touch high above the
The roof structure is approximately
75m-long on one side and 65m-long on the
other. It curves inwards, from the south and
north ends, and then rises up in the middle
to a maximum height of 25m.
Two ‘ribbon’ trusses, sat atop of each
building, help form the undulating shape of
the roof structure.
“So as not to overload the existing Coal
Drops buildings, new independent steel
frames have been erected carefully within the
existing brickwork structures to support the
roof steelwork,” explains BAM Construction
Manager Ewen Hunter.
The trusses are fabricated from 610mm
CHS members with 508mm circular hollow
sections (CHS) verticals and bracings made
from 219mm CHS sections.
“To create the complex geometry of the
sweeping roof structure, steel was the only
choice and CHS sections were used as they
could be bent to form the curved ribbon
trusses,” says Arup Senior Engineer Simon
The trusses are both created from four
individual segments eight in total, each one
bespoke, due to the curvature of the roof and
the splay of the buildings.
To form the segments, 20 individual
components were brought to site by
steelwork contractor Severfield and then
bolted together before being lifted into place
by a 500t-capacity mobile crane.
In order to minimise the amount of
working at height activities, Severfield
also carried out paint touch-up and purlin
installation on the ground.
A series of temporary trestles were
installed to support the truss segments
during the erection sequence. The trestles
remained in place until the roof structure
and its supporting steelwork was complete.
Above the trusses the new roof is
primarily supported by a compressiontension
system, spanning the distance
between the Coal Drops buildings.
This is supported on new steelwork at
each end within the east and west buildings.
The compression aspect of the system is
made up of four fabricated box ‘giraffe’
girders (they look like giraffe necks in 2D
The ‘giraffe’ girders, which span 50m
from building to building, are 1,000mmdeep
× 600mm wide with 40mm flanges.
The tension is taken through a single tie
(made from a series of plated steel elements),
that is connected to the bases of the ‘giraffe’
At the middle point of the roof, there is a
large kink where the two sides nearly meet -
this is the ‘kissing point.’
As there are huge bending moments
generated in the steelwork in this area, a
large 100t steel node is positioned at this
This ‘kissing point’ node, that resolves
force through the kink at the centre of the
Coal Drops Yard, London
A bespoke curving steel-framed roof structure
straddles two restored buildings and provides a
new retail destination with its crowning glory.
© Hufton + Crow