NSC
October 18
Designed for cyclists and
pedestrians to cross from
Camley Street into King’s Cross
Central, the Somers Town
Bridge is a landmark redevelopment project.
It spans 38m, weighs 52t and it is only
1,100mm deep at mid-span and 400mm
deep at the ends.
In keeping with the Victorian heritage
of the area, the bridge is unadorned
and streamlined, focusing attention
on extremely detailed and precise
craftsmanship and high-quality materials.
A sweeping ramp leads people up to
the bridge and over the water with an
elegant parapet transitioning from planed
hardwood to stainless steel.
One of the planning design drivers was
that this should be a ‘green bridge’. This
was achieved by taking minimum material
use to the extreme which would become
the defining feature of the architectural
simplicity. With the use of steel, and its high
recycled material content, this has resulted
in a low carbon solution.
Secondly, the history of the area is one
of heavy industrial use and the bridge
provides the opportunity to remediate
the contaminated land and replace it with
parkland of higher biodiversity value.
According to the project team the use
of steel construction offered two significant
benefits: Firstly, offsite fabrication and
single piece lifting was required to avoid
disruptive construction methods on this
heavily trafficked section of canal. This also
enabled the offsite and on-site construction
activities to run in parallel with associated
programme benefits.
Secondly, the eastern abutment was
integrated inside existing Victorian brick
arches. A lightweight deck allowed the use
of small diameter piles and a low headroom
piling rig that could operate inside the
arches. This had the additional benefit to
maximise retail space within the arch space.
The bridge was optimised to meet the
architect’s aspiration for a slender structure
that would minimise the shade on the
canal. Non-linear analysis of the slender
deck ensured that the slenderness would
not compromise safety and would provide
maximum comfort for users of the bridge.
Particular care was placed on satisfying
the user comfort criteria, which led to the
use of bespoke tuned mass dampers at
mid-span to suppress vertical and torsional
dynamic modes of the deck.
Every single element of the bridge is said
to have a structural meaning and function.
It was designed so no longitudinal stiffeners
would be needed, simplifying the structure
as well as reducing fabrication complexity
and cost.
The curved plates connecting the web
and deck plates are an example of design
efficiency. The restraint that u-frame
stiffeners provide to the top flanges in
compression is significantly undermined
by flexibility of the web-to-deck connection
when, typically, both plates are connected
with a sharp angle. Using curved plates
eliminated this flexibility and increased the
efficiency of the system.
In summary, the judges say a
sweeping ramp leads up to this almost
impossibly slender steel bridge. Designed
for pedestrians and cyclists, the bridge
improves access into King’s Cross Central,
a landmark redevelopment project. The
simplicity of its unadorned and streamlined
form focuses attention onto the bridge’s
high‐quality materials and precise
craftsmanship.
32
SSDA 2018 C O M M E N D A T I O N
FACT FILE
Architect:
Moxon Architects
Structural
engineer:
Ove Arup &
Partners Ltd
Steelwork
contractor:
S H Structures Ltd
Client: King’s Cross
Central Limited
Partnership
Somers Town Bridge,
London
Crossing the Regents Canal in London, Somers Town
Bridge meets the structural demands with the very
minimum of materials.
© John Sturrock
© Simon Kennedy
/Steel_construction_products#Stainless_steel_products
/Sustainable_steel_bridges#Minimum_CO2_and_energy_burdens
/Design_for_steel_bridge_construction#Fabricating_the_steelwork
/Sustainable_steel_bridges#Lightweight_construction
/Half-through_bridges
/Design_of_steel_footbridges#Dynamic response
/Stiffeners#Longitudinal_stiffeners
/Design_for_half-through_construction