2. 24 NEW CIVIL ENGINEER 27.05.1O | www.nce.co.uk
EAST LONDON LINE: INTRODUCTION
www.nce.co.uk | 27.05.10 NEW CIVIL ENGINEER 25
upgrade the East London Un-
derground Line that ran from
Shoreditch to New Cross Gate
since 1997. London Underground
had the idea to take a railway
into Hackney on a disused
viaduct that had once carried the
North London Overground Line
from Broad Street Station, which
had disappeared under the
Broadgate development in 1986.
It got Transport & Works Act
(TWA) powers for the scheme,
which was then expanded again
when it was realised the railway
could interconnect with the
North London Line. Another
Transport & Works Act was ac-
quired, and as the project by that
stage had effectively become
part of Overground rather than
Underground rail, it was passed
to the newly formed Strategic
Rail Authority (SRA) to manage.
ELL plans languished there
without a champion. But over
at Transport for London it did
have its backers – Smith and his
managing director Ian Brown
at TfL’s developing London Rail
division in particular. And when
the SRA wound up and the route
was bequeathed to TfL in 2004
they fought for, and won the
funding.
“There was pressure to make
a decision as the TWA powers
were about to run out, and then
the Olympics came along, which
finally tipped the balance and we
could get on with building the
project,” Smith says.
Peter Richards was brought
in from the SRA to run the job
as infrastructure director for the
now dubbed London Over-
ground, along with Mike Stubbs
as engineering director, and they
got stuck into design.
There had been a brief flirta-
tion with funding the route
through private finance. “But
the ELL is a grey asset,” Smith
says. “There is a lot of old in-
frastructure it would have been
difficult to box up for PFI, and a
PFI takes time to put together.”
With the 2012 Olympics fast ap-
proaching, it was decided to go
for a design and build option.
It was a good decision. The
scheme, built by a Balfour Beatty
Carillion joint venture (BBCJV),
opened early on 23 May. BBCJV
won the contract in October
2006, started design immedi-
ately, and then started the major
structures in 2007. It got onto the
tunnel and south sections of the
site when the old East London
Underground was closed in
December 2007 and handed over
in late January 2008.
“From the start, we stressed to
everyone that this job is about
delivering an operational railway
– infrastructure, rolling stock
and operations,” says Richards.
“We have managed the integra-
tion between these aspects and
given the responsibility for man-
aging the interface between the
existing infrastructure and main
works structures and rail sys-
tems to Balfour Beatty Carillion
as our main works contractor.
“That is why we went for a
single NEC3 design and build
main works contract.
“It has meant that BBCJV
has managed the interfaces, and
all the responsibility has rested
with one party to get on and do
the whole thing.”
When Richards set up the job
he wanted to create momentum,
so he formed an integrated client
team to manage the job and
drive its progress. This included
himself, Parsons Brincker-
hoff’s Ashok Kothari as head of
programme management and
designers from Mott MacDonald
as technical adviser to the
project.
Refurbishment work along
the route on some of the older
structures like the Kingsland
Viaduct was let as enabling
works contracts to Murphy and
Taylor Woodrow (now Vinci
Construction).
“Refurbishment is risky and
it was prudent to do some of
that first before we let the bigger
contract,” Richards says.
“And then, as a client team,
we worked very hard towards
letting the main works contract
to programme.
“We didn’t let ourselves slip.
By doing that we created float
for the rest of the project and
that has helped us come in early.
We are delighted to have opened
on 23 May, ahead of a pro-
gramme set back in 2004.”
O
ne day after the
opening of the core
route of the London
Overground East
London Line last month, pas-
sengers were wandering around
wide-eyed, taking in the wonder
of the capital’s newest rail route.
Londoners who know the
detail of the Underground better
than their bank pin numbers
were cooing contentedly to
themselves while looking at a
map of the route which revealed
a whole new circuit board of
travel possibilities. As the first
section of ELL opened they
could go from Dalston in Hack-
ney in the north, south to the
Docklands at Canada Water and
then on to New Cross. From this
week, since the full line opened
on 23 May, the route will take
them as far into the south Lon-
don suburbs as West Croydon
and Crystal Palace.
By early next year when phase
1a of the East London Line
opens, Croydon will have a direct
connection to Highbury and
Islington, and at Dalston travel-
lers will be able to switch onto a
newly upgraded North London
Line to go east to Stratford and
the Olympics or west to Willes-
den Junction and Richmond.
And by 2012, construction of a
link from the East London Line
at Surrey Quays to railway at Old
Kent Road will allow a western
trip to Clapham Junction via
Peckham Rye and Wandsworth
Road and link to the Overground
Clapham Junction to Willesden
Junction Line.
The capital will have an outer
orbital metro railway under the
banner of London Overground,
interconnecting along the way
with its Underground lines and
serving 20 of its 33 boroughs;
and commuters will have oppor-
tunities aplenty to avoid central
bottlenecks when they are trying
to cross the city.
The key to creating this will
have been a £1bn Transport for
London investment in infra-
structure and new rolling stock.
This has reinvigorated and
expanded the old East London
Line Tube line, reusing Victorian
infrastructure and introducing
some new modern landmarks
along the way.
There are going to be huge
benefits in terms of regeneration
and new jobs for some of the
less developed parts of the City,
rail-deprived Hackney will at
last have a metro, and east and
southeast London will acquire
some life changing infrastruc-
ture.
Around 33M passengers are
expected to be using the route
every year by 2011, rising to a
projected 39M by 2016.
“The really good part of this
job,” says London Rail chief
executive Howard Smith, under
who’s remit the East London
Line falls, “is that we are chang-
ing the face of London and the
way we think of and use London
in a permanent way. It is really
dramatic.”
There has been a plan to
east end
efficiencyThis week the London Overground
East London Line opened a full service
from West Croydon in south London
to Dalston in the north. In a remarkable
achievement, the project has been
delivered early. Jackie Whitelaw reports.
“As a client team, we
worked very hard
towards letting the
main works contract
to programme”
Peter Richards,
infrastructure director
London Overground
“We are changing the
face of London and
the way we think of
and use London in a
permanent way.
It is really dramatic”
Howard Smith,
London Rail
Client London Overground for
Transport for London
Other parties London
Underground, Network Rail
Contractor Balfour Beatty
Carillion joint venture
(BBCJV)
Contractor’s designers Scott
Wilson, Tony Gee & Partners
Programme manager Parsons
Brinckerhoff
Client’s technical adviser Mott
MacDonald
Rolling stock Bombardier
Operator LOROL
Signalling,communications and
power systems, 3.5km of new
or refurbished viaduct from
Whitechapel to Dalston Junction;
3.2km of track in tunnel south of
Whitechapel to Surrey Quay
New stations at Dalston
Junction, Haggerston, Hoxton
and Shoreditch High Street;
refurbishments at Whitechapel,
Shadwell, Wapping, Rotherhithe
and Surrey Quays; an
operational control centre;
depot; and 44 four car
Electrostar 378 trains – 20 for
the East London Line and 24 for
the North London Line.
WHO’S WHO
EAST LONDON LINE IN BRIEF
Stratford
Dalston Junction
Haggerston
Hoxton
Shoreditch High Street
Highbury &
Islington
Blackhorse Road
Whitechapel
Gospel
Oak
Shadwell
Canada Water
Surrey Quays
Queens Road
Peckham
Denmark Hill
West Brompton
Kensington (Olympia)
Shepherd’s Bush
EustonKensal Green
Queen’s Park
CENTRAL LONDON
Willesden
Junction
West Hampstead
Harlesden
Stonebridge Park
Clapham
High Street
Kew
Gardens
Gunnersbury
Clapham
Junction
New Cross
Brockley
Honor Oak Park
Forest Hill
Sydenham
Penge West
Anerley
Norwood Junction
Crystal Palace
West Croydon
New
Cross
Gate
Peckham
Rye
North West
to Watford
Junction
East to
Barking
To Richmond
KEY
Phase 1 opened 23 May 2010
Phase 1a completed by 2011
Phase 2 completed by 2012
OVERGROUND
East London Line is vital for creating
an outer orbital railway around the
capital. Phase 1 opened on 23 May.
City slicker: The East London Line is a
vital new link to London’s financial heart
east london
line REBORN
MAJOR
PROJECT
REPORT
LONDON OVERGROUND: THE FUTURE
3. venture finally got onto the line
three months early at the end of
January 2008.
That is when the scope of the
job began to develop. There was
the depot to add in. And two
bulk supply points for power.
“Those two 132kV bulk supply
points came on top of three 33kV
traction substations already in
the contract, and those three had
to change from pre-assembly
to larger built insitu on site
versions,” says Balfour Beatty
Carillion construction director
Adam Stuart.
An enabling works contract
had beefed up the Victorian
Kingsland brick arch viaduct
between Shoreditch High Street
and Dalston. “But that still left
BBCJV a lot of work in further
assessment and strengthening,”
says Stuart.
The six “tunnel” stations
between Whitechapel and
Surrey Quays also needed much
more work than originally
thought and London Over-
ground decided to properly
refurbish them, he adds.
“A grade separated junction
was also introduced to make the
link with phase 2 to Clapham
Junction so as not to disrupt
East London Line running when
that project goes ahead.
“One of the things I am most
proud of here is that the scope
has increased very significantly
yet our design, construction
and commissioning period
increased by only five months,”
says Stuart.
BBCJV drove itself along,
and for added momentum it
had a set of about one hundred
non-contractual milestones to
hit, worked out with Parsons
Brinckerhoff.
“In December 2008 we said
that we’d have all the structures,
track, and operational systems
complete to start test train
running 10 months later on 5
October 09, and we did,” says
Stuart. “And from that date we
ran up to six of the new trains
every day for four months during
which we finished the new
station buildings behind the
platforms; our track gives a very
smooth ride and the Invensys
signalling system proved fault-
less.”
“Also in December 2008 we
gave a date of 17 January 2010 to
hand over to trial operations and
on that very date we started the
week long process of handover
to Transport for London for trial
operations,” adds Casebourne.
“In parallel the refurbishment
of the tunnel stations was
completed and the customer
information systems were
finished. Now customers are on
board and everything is working
reliably.”
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EAST LONDON LINE: Management
W
hat is remark-
able about the
management
of the London
Overground East London Line
construction work is that the job
has so successfully beaten its
deadlines; particularly when the
scope of the scheme was some-
what fluid when the job was
tendered.
Balfour Beatty Carillion Joint
Venture (BBCJV) bid for and
won the basic project against
strong competition and with
the addition of many changes.
The final job is coming in at
£700M or thereabouts after new
elements were added in and the
amount of work required became
clearer as the construction teams
got stuck in on site.
“We knew there would be
additional work in the central
section but we couldn’t find out
how much until we took posses-
sion of the railway from London
Underground (LUL),” says
London Overground Infrastruc-
ture director Peter Richards.
“We also knew the depot, for
instance, had to be added in
but the contractor could not
price that in the original tender
because the designs from
[rolling stock supplier] Bombar-
dier were still being developed.
“That is why we went for a
target cost design and build
contract rather than fixed price.”
But Richards points out that
there was always a total budget
and as the work grew, “we
adjusted the scope to suit the
budget.”
“Is it safety critical?” was the
mantra. If it was, then the money
was found, if not, then as much
cash was saved on each opera-
tion as possible so there was
some to spare when needed.
That approach required close
collaboration between the client
team, BBCJV and its supply
chain throughout the works.
“The closely cooperative
culture of the job has been vital,”
says Balfour Beatty Carillion
project director Mike Case-
bourne. “It is one of complete
openness; no secrets, shared
decisions and facing and solving
problems together.”
Richards agrees: “We have
some very dedicated people on
this project. There is a collabora-
tive, positive culture which has
all helped towards getting the
job out the door on time and on
budget.”
Actually the railway is two
months ahead of schedule. The
original opening date set at the
start of the job in 2004 was 30
June 2010. The full line opened
on 23 May to coincide with
the seasonal timetable change;
and passengers were using the
central section of the route from
27 April. Not bad for a complex,
modern railway squeezed into a
packed capital city.
“We are particularly pleased
about getting the route into
service early as it will have a
huge benefit to the travelling
public,” Richards says.
“Right from the start,
when we signed the contract
on 20 October 2006 we had
to remember that we had
committed to design, construct,
test, commission and deliver
an operational railway, not just
its separate structures and rail
systems,” says Casebourne.
“It was a requirement driven
contract – for example to design
for three minute headways
between trains.”
“There were 6,000 require-
ments and about two thirds of
them were changed or modified
as we all got on with the job,”
says Balfour Beatty Carillion
engineering director Andy
Nettleton. “Without strong
management of a resilient,
responsive design organisation
we would never have achieved so
much in such a short time.”
The key to pinning down the
scope was gaining access to the
old Underground section of the
route between Shoreditch and
New Cross Gate.
“We pushed to get London
Underground to agree to get the
route closed as early as possible,”
says Parsons Brinckerhoff head
of programme management
Ashok Kothari . LU agreed to
shut down the line in December
2007 although it had originally
wanted to keep it open until the
following April.
There was a slight delay
while Underground upgrade
contractor Metronet stripped
out all of its assets but the joint
Working
Together
as a team
SAFETY
The London Overground East
London Line scheme has had
an excellent safety record over
the duration of the project.
The site has twice recorded 1M
accident free hours under the
Reporting of Injuries, Diseases
and Dangerous Occurrences
Regulations (Riddor) 1995.
This was achieved in
December 2008 and again in
November 2009.
The job hit over 1.5M
continuous Riddor-free hours,
and the current accident
frequency ratio of reportable
accidents to 100,000 man hours
worked is an excellent 0.12, a
performance which recently
landed a coveted Rospa Gold
Award.
“We have had a really big
push on the safety culture on
this project,” says health and
safety manager Mike Davies.
“We have focused on the
supervisors and gangers and put
in some fun incentives like group
of the month winning a fleece
each,” he adds.
Collaboration between client, contractor
and supply chain was crucial as the
construction project developed in scope,
writes Jackie Whitelaw.
MaNAGING THE TEAMS
COMMUNITY RELATIONS
As BBCJV project director, Mike
Casebourne has had to manage
640 professional staff, and 600
designers off site in the offices of
Scott Wilson and Tony Gee and
other designers.
He is aslo responsible for 2,500
operatives on site at peak and
up to 1,000 people engaged in
the offsite manufacture of all
the elements for the job all over
the UK. At peak, the project was
spending £30M every four weeks
or £1.5M a day.
The job was divided into four
construction sections under the
control of four BBCJV senior project
managers; northern civils under
Andy Swift; southern and central
civils under Paul Rasmussen; rail
systems under Elliott Young and
the depot under Howard Williams.
These were supported by design,
commercial and administrative
managers within their teams and
reporting also to their department
directors.
“We had to design,
construct, test,
commission and
deliver an operational
railway”
Mike Casebourne,
BBCJV
“The scope increased,
yet our design,
construction and
commissioning period
increased by only five
months”
Adam Stuart, BBCJV
Team work: The close
cooperation culture of the job
has been vital to successful
construction of complex projects
like Dalston Junction station
Community relations were a vital
part of successful delivery of the
East London Line with full time
community relations managers
working for London Overground
and BBCJV.
The usual issues of working
hours, noise and dust had to be
addressed but it was either end of
the project – at Dalston and New
Cross Gate where there were most
sensitivities.
“There was some resistance to the
idea of Dalston being gentrified,”
says head of communications for
London Rail Julie Dixon. “But we
always stress that the East London
Line is a regenerating railway with
the priority being to give people
access to jobs which has helped
allay concern.
“At New Cross Gate people were
unhappy at the idea of a 24 hour
train depot. The solution was to
get the residents involved, listen
to them and respond to their
concerns. For instance, the depot
will have low level lighting so as
not to create a nuisance.”
east london
line REBORN
MAJOR
PROJECT
REPORT
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EAST LONDON LINE: DALSTON & NORTHERN STRUCTURES
www.nce.co.uk | 27.05.10 NEW CIVIL ENGINEER 31
T
he northern section of
the London Overground
East London Line,
running mostly on once
abandoned Victorian viaduct,
has to make a swing eastwards
as it reaches the edge of the
City of London. This enables it
to link up with the old London
Underground East London
Line route to south London.
Two major bridges, substantial
new viaducts, reshaped cuttings
and a new, relocated station at
Shoreditch High Street, are just
some of the works needed to
make the link.
The new section takes the line
through and across Shoreditch
High Street, and on into the
historic Bishopsgate Goods
Yard area, once one of the
industrial wonders of Victorian
London. After three decades
of near dereliction, what was
once a huge, two-level railway
unloading depot with a half
kilometre length of vaulted brick
arches supporting its rail tracks
has become the largest potential
development zone in London
and is ripe for major office and
residential schemes.
Early work for the BBCJV
meant clearing thousands of
tonnes of brick rubble from the
northern half of the nearly 5ha
site. This was the residue of
pre-contract demolition works
which took away many of the old
arches. Some remain, including
the famous and now listed
Braithwaite brick arches, built
by Victorian civil engineer John
Braithwaite in the 1830s.
“We established a truck route
out of the yard using a tempo-
rary Bailey bridge,” says Andy
Swift, BBCJV project manager
for the northern section civils
works. The temporary bridge
took construction traffic over
famous Brick Lane, known for
its curry restaurants. The trucks
then passed over a still intact
Network Rail bridge, known as
GE19, whose later demolition
by Murphy and replacement by
BBCJV was one of the largest
jobs in this section. It crosses
a six track wide cutting for the
main lines between Liverpool
Street Station for the East Coast.
Just beyond this bridge the
line dips into cutting and then
underground at the Valence
Road portal. The brick rubble
the trucks carried was used
OTHER
STRUCTURES
spanned the line of the
tunnel, carrying the building
loads into the ground. But there
was concern about differential
settlement between this section
of foundation and the rest of
the site, which was piled, so an
alternative, piled, solution was
developed.
Two rows of bored piles have
been sunk on each side of the
tunnel line, topped with pile
caps that support walls carrying
the podium slab, the station
concourse and the multi-storey
development above.
“This acts as a ground level
bridge, one of the biggest on the
job, so they can put the Crossrail
tunnel in much later without too
much settlement,” says Anstiss.
It sounds straightforward, but
each of the 40 piles in these four
rows measures between 1.8m
and 2.1m in diameter, and has
been bored to a depth of 40m –
only just above the chalk layer
that underlies the London clay.
The reinforcement cages alone
weighed up to 13t, and required
two splices to enable them to be
lowered into the pile bore.
An inventive piling solution
was also needed as part of the
remedial work to the Forest
Road bridge, which spans the
rail cutting at the southern edge
of the podium slab.
In the original design, all of
this post-tensioned concrete
structure was due to be demol-
ished and replaced by a new
bridge with no parapet on one
side, to allow buses to come off
the Kingsland Road and into a
new bus station being built on
the podium slab. However, the
BBCJV felt that full demolition
would be a complex process, as
the structure is full of services
that would have had to be
diverted at great cost. It was
also very close to neighbouring
properties that would be affected
by noise and vibration during
the demolition.
Instead BBCJV proposed that
the structure be retained, and
turned into a “hybrid”, with the
post-tensioning remaining in
place on the eastern half, while
the parapet on the western side
was demolished to allow the
buses to turn off, with this half
of the bridge supported by one
of the walls designed to take the
podium slab loads. The new pier
wall is topped by an I-beam that
is tied into the existing bridge
reinforcement.
Beneath the wall is a large pile
cap and a total of 66 piles, each
300mm in diameter. “We wanted
750mm diameter piles, but when
we decided to keep the bridge,
the question was: ‘how do we get
the rigs in?’” says Anstiss.
Rigs large enough to sink
750mm diameter piles to the
depth required would not have
fitted under the bridge structure,
so the design was changed to
450mm diameter piles instead.
“That would have worked, but
we had a problem with ground
conditions,” says Anstiss. “It
looked OK from the boreholes,
but when we started piling, water
started boiling up from the base.
It meant that 450mm diameter
wouldn’t really work because
there wasn’t a rig available to
allow us to manage the boiling
sand.”
Instead, the design had to
be changed again for 300mm
diameter piles, with construction
carried out in a sequence that
saw a series of casings driven,
with the piles augered out inside
them. “We had to introduce
“We wanted 750mm
diameter piles, but
when we decided to
keep the bridge, the
question was ‘how do
we get the rigs in?’”
Guy Anstiss,
BBCJV
“We established a
truck route out of
the Bishopsgate
Goods Yard using a
Bailey bridge”
Andy Swift,
BBCJV
The new station at Hoxton is
built inside an existing set of
rail arches, with the concourse
constructed by punching through
the brick piers.
To create this space, ground
engineering specialist Bachy first
installed low headroom mini-piles
either side of each existing pier,
and a ground beam was cast
on top. Holes were then drilled
through the brickwork, and needle
beams threaded through the top of
the pier, and jacked off the ground
beam to support the arch roof
while the material below
was removed to form the
required space.
New columns and a lintel beam
were then grouted in place to form
a portal frame within the pier,
and the jacks removed to allow
the brickwork to sit back down
on top of the frame. The BBCJV’s
engineer Scott Wilson had to carry
out considerable finite element
analysis to ensure the new design
could carry loads from the tracks
above. For Haggerstone Station,
the old viaduct was demolished
and a new station built.
HOXTON AND HAGGERSTON STATIONs
bentonite before we hit the
sand, and then keep excavating
through the bentonite,” says
Anstiss. “Then we had to grout
under pressure to replace the
bentonite, and at the same time
install the 18m long reinforce-
ment cages.”
Now that Dalston Junction
station is complete, much of the
massive civil engineering work
will go unnoticed by passengers,
but during construction it was
one of the most complex parts of
the entire scheme.
At maximum there were 306
operatives working on this part
of the site, and the major plant
used to construct it included a
64m concrete pump – the biggest
available in the UK at the time.
With construction starting
on the apartments that will sit
on top of the podium slab and
passengers starting to use the
bright, airy, stainless steel lined
concourse, this ultra modern
station will soon be a centre
point of modern Dalston.
Crossrail crossing: Piling at Dalston included working around the Crossrail route
Tight spot: Hoxton station was snugly fitted under Kingsland viaduct
Catalyst: The station at Dalston Junction is expected to trigger regeneration
Transfer beam: Massive steel beams will carry
properry developments above Dalston Station
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EAST LONDON LINE: DALSTON & NORTHERN STRUCTURES
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to infill part of that cutting,
reshaping the gradient and
approach to the new GE19
bridge. It also helped fill another
part of the cutting which
continued on the Bishopsgate
side, swinging around towards
Liverpool Street station.
This was where the original
Shoreditch Station was sited.
The new Shoreditch station
is set in the length of the old
goods yard, along much of a
new viaduct which carries the
track through the yard space
and out across Brick Lane. This
Bishopsgate viaduct carries the
line on 400m of a new concrete
elevated way, some 10m or so
above ground.
The viaduct comprises pairs
of mainly 6m high columns
which are mainly circular or
elliptical in cross section. They
carry a large 3.5m deep edge
beam on either side. “In fact
the depth varies at centre span
giving them a slightly arched
shape” says Swift.
The beams form the platforms
and are connected by a concrete
slab which forms the deep
trackwork trough between them.
Spans between are 21m to 23m
long apart from an extra long
34m span across the street at the
station entrance.
Concreting for these beams
was reasonably complicated
since they required a mass of
heavy T40 bar reinforcement, up
to five layers thick, which meant
care was needed in placing the
concrete. “We used limpet vibra-
tors on the formwork which gave
us issues of noise and vibration
to manage, since this is a busy
area with a lot of residential
property around,” says Swift.
Clusters of five bored piles
support each end of a series of
single pile caps as wide as the
viaduct on which sit each pair
of the columns that support
the viaduct above. One cluster
was bored very close to London
Underground Central Line
tunnels and monitoring equip-
ment was set up to give early
warning of possible distress.
Fortunately there was none.
Piles are as much as 30m deep
under the station section and
around 22m deep elsewhere.
They were driven into London
clay on which much of the site
rests.
“The clay rises from the
Brick Lane end somewhat as
you approach Shoreditch,” says
Swift. There is terraced gravel
beneath and for the longer
piles that meant using a “wet
pile” system to bore them, with
polymer support, into water
saturated gravel.
Piles were “substantial” says
Swift, between 1,200mm and
1,500mm diameter.
The larger diameter was used
to achieve a shorter pile in a few
places, allowing the pile end to
remain in clay and avoiding the
need for the polymer. Bachey
Soletanche was subcontractor
for the piling.
The longer piles carry the
heavier loads in the central part
of the viaduct where the 200m
length of the new Shoreditch
station is located. The entire
station at rail level is enclosed in
a precast concrete box, creating
a kind of “tunnel in the air”. The
box tube comes in two widths,
a central portion enclosing the
100m long platforms and two
smaller parts extending the
station enclosure at either end;
there is an option for future
expansion of the platform
lengths into these.
The point of the enclosure is
primarily to safeguard the line
from future construction and
development planned for the
entire Bishopsgate area, with
over-site “air rights” construc-
tion around the station, possibly
including a 40 storey high rise
office development. Work is
imminent, although delayed
temporarily by the economic
situation.
“The station enclosure is
really an expensive, perma-
nent crash deck to keep trains
running while work is done later
by the developer,” says Swift.
It is built from precast portal
frame sections attached to the
viaduct at 7.5m intervals. Three
2m high panels are bolted to
each side of these before an
insitu top deck is formed and
poured.
There were challenges on the
longer GE19 bridge to the east
of the station site. This was
fabricated and assembled by
Fairfield Mabey. The assembly
of the Warren truss bridge which
carries the new railway on a
85m span over the six Liverpool
Street main lines, went well. It
was fully assembled on tempo-
rary falsework on the track
alignment in the space which
became the approach ramp, and
push launched into place.
“It was powered over using a
multi-axle transporter provided
by Abnormal Load Equip-
ment” says Swift. A 30m long
nose section was added for the
launching at the front end and
the ALE transporter sat at the
rear end. “It was a balancing
exercise to keep the nose up”
says Swift “so we concreted the
back end deck and added more
weight, leaving the front deck
to be done later. The launching
was done with the strand jacks
between the permanent concrete
abutments being used as the
launch fulcrum, and the ALE
transporter at the rear end.”
West of Shoreditch Station,
the line crosses Shoreditch
High Street on a 35M span
bowstring arch bridge fabricated
by Fairfield Mabey partly within
the Bishopsgate Goodsyard
site. There, the firm welded the
curving steel beams to form the
bow and set the vertical hangers.
A critical part of the job
was a major crane lift for the
completed 330t bowstring arch
bridge, using the 1,200t Sarens
crane on a May weekend in 2008.
“The lift only took a couple of
hours but 12 months of prepara-
tion were needed beforehand”
says Swift, not least because the
busy crane is much sought after.
“We also had to coordinate
all the emergency services, local
authorities, and others for a road
closure,” Swift adds. The site
needed proper preparation for
the crane which arrived on some
forty trucks and took several
days to assemble. Ground had to
be properly cleared, and an area
piled to support the crane.
The viaduct continues west
of Shoreditch High Street with
the Holywell viaduct, curving
sharply to take the line back
across the street as it links north
to the existing Victorian brick
viaduct further on. Five 20m
spans were needed, built close
alongside a listed and untouch-
able building on Shoreditch
High Street, running within
330mm of it at one point.
This part of the work was
preceded by significant archaeo-
logical digging within the old
Holywell Yard. The Museum of
London was delighted by the
discovery of the remains of an
old monastery, including foot-
ings and columns, various burial
sites, plates and knives.
“The station
enclosure is really
a permanent crash
deck to keep trains
running while work
is done later by the
developer”
Andy Swift,
BBCJV
“The GE19 bridge
was powered over
using a multi-axle
transporter. It was a
balancing exercise to
keep the nose up”
Andy Swift,
BBCJV
Shoreditch High Street: A 35m span bow arch bridge is lifted into place
GE19: The bridge was launched over six mainline railway tracks
New link: The line runs on a mixture of new and
refurbished viaduct from Dalston to Shoreditch
8. 36 NEW CIVIL ENGINEER 27.05.10 | www.nce.co.uk
EAST LONDON LINE: SOUTHERN SECTION
www.nce.co.uk | 27.05.10 NEW CIVIL ENGINEER 37
O
nce the ELL emerges
from its tunnels just
past Surrey Quays
onto conventional bal-
lasted track, it might be thought
there was less to do.
But renewing bridges,
providing for new connections
to the mainline and future
London Overground extensions
and installing big flyover at New
Cross were all significant chal-
lenges.
And there was the building of
a brand new carriage servicing
depot to add into the mix.
Cope Street Bridge
Two significant bridges carry
busy South London road
connections across the line
just after Surrey Quays station,
where it is still in cutting, rising
out of the river tunnel section to
surface running. Both of these
were old Victorian bridges, 10m
wide, comprising parallel cast
iron I-beams and masonry jack
arch infills. Both carried a single
carriageway road and pedestrian
pavement and were supported
in the middle by a central pier.
Originally rail tracks ran either
side of the pier but now they
only run on the western side.
The cast iron piers did not
meet modern derailment resist-
ance standards and had to go. At
the Cope Street bridge, an initial
scheme for a single unsupported
span was dropped because the
deck beams would have been too
deep. Instead new concrete piers
were installed but set back from
the live track, creating one long
and one short span.
Simple replacement of the
deck above was complicated
by the high concentration of
services carried within the decks,
most critically a fibre optic cable.
Diverting it to a temporary
bridge during the work would
have been very expensive –
around £250,000. “And diverting
it back afterwards would have
doubled that,” says Andy
Bradshaw, BBCJV construction
engineering manager for the
section.
Costs were contained after a
value engineering study devised
a scheme that left the narrow
strip of bridge deck with the
fibre optic cable intact while the
rest was rebuilt with new precast
concrete beams. “And then we
only had to move the cable once
onto the new part and finish the
construction,” says Bradshaw.
Rotherhithe New Road Bridge
At the second bridge, Rother-
hithe New Road Bridge, an even
more expensive utility diversion
was needed to handle several
high voltage cables which served
most of South London. These
were embedded in a concrete
block which had replaced one of
the original jack arches between
two I-beams.
Rather than a double move for
the cables at an overall cost of
£1.4M, and some risk of blacking
out a big part of the conurbation,
BBCJV devised a system to leave
the block intact and rebuild the
rest of the bridge around it.
The bridge was tackled in
two halves in order to leave a
carriageway open for busy traffic.
Most of one side was demol-
ished first, leaving the power
line slab in place supported on
its portion of the pier. Once the
new steel beams were installed,
two transverse I-beams were
then attached underneath the
new deck, to support the power
line slab, on either side of its
support pier.
With the power cable slab load
transferred to these temporary
hanging beams, the pier could be
demolished. A third steel I-beam
was then installed between the
temporary ones, to be a perma-
nent support, while the outer
two were removed.
The new Rotherhithe bridge
has one single span. It is longer
than before but does not run the
full length of the old bridge’s
two spans. Instead the far abut-
ment was built outwards on
the disused side of the cutting.
Rebuilding the bridge in this
way produced a net saving to
the client of around £1M, says
Bradshaw.
Further south in the Silwood
depot, there is to be an eventual
connection to the South London
Line. Points suffice to make
the transition on the up-line
into London, but the down-line
trains will have to dip under the
up line to travel west to Clapham
Junction.
Secant piled walls were used
to form a new cutting taking
the connecting track down
and around, with a slab placed
across the top of this cutting to
carry the up-line. The new grade
separated junction has been
built to avoid service disruption
in the future when the project to
connect the East London Line
to Clapham Junction gets under
way.
Further south, a third road
bridge was replaced, this time
with the straightforward demoli-
tion and lifting in of a new deck
with a 1,000t crane. Apart from
finding space between buried
services to put crane outriggers,
the main problem was to avoid
traffic closures on weekends
when Millwall Football Club had
home games, says Bradshaw.
New Cross Gate Flyover
A much bigger grade separated
crossing was needed near the
end of the renewed East London
Line section where it merges
with and uses the existing
Network Rail slow lines at New
Cross Gate on the route south
to Croydon and Crystal Palace
at New Cross Gate. New Cross
Gate flyover avoids the need for
a four-track ladder of switches
and crossings to carry the ELL
trains across four near-capacity
main line tracks onto its own
line which runs past the new
service depot.
The connection takes north-
bound trains heading for the
ELL off the main slow line and
then up an inclined concrete
ramp to a 75m steel bridge which
spans the four tracks. A short
32m steel span continues the
10m wide bridge from a concrete
pier onto another inclined
concrete ramp that carried the
trains through the new depot
and onto the ELL’s dedicated
line.
The new ELL depot sits on old
sidings which for some years
had become a local authority
site for impounded cars
says Mark Walker of BBCJV
who supervised the depot
construction.
The depot is domnated by the
four-track, four-crane, four train
rolling stock maintenance facility
and its three storeys of offices all
housed in a huge 90m by 40m
by 12m high rectangular steel-
framed, steel-clad building. Inside
the depot are three raised tracks
enabling clear access below
the trains. The fourth track is
equipped with synchronized jacks
capable of lifting a whole train
in one minute for the purpose of
bogie changing.
Another 90m building, split
longitudinally into two, has one
track dedicated to a twin-headed
wheel lathe and a second in the
other half committed to heavy
cleaning and painting. It also
has a blast and fire proofed top
floor dedicated to an operational
control and signaling centre
which allows signallers 10
minutes to safey shut down all
rail systems in the event of a fire.
NEW CROSS GATE DEPOT
neering rethink suggested
sinking jacked caissons with
mucking out by long reach exca-
vator “which paid a health and
safety dividend because you
don’t need anyone in the shaft
until you have reached forma-
tion level and pumped out,” says
Bradshaw.
This went well until the time
came to make the first cross
passage, excavating through
what it had been thought would
be firm London clay. Instead old
rotten timbers, possibly some
temporary works left in place by
builders of the wall, were encoun-
tered. These timbers posed a
problem because, once disturbed,
it was realised that they were
providing a water flow route from
the terrace gravels above. “And
since the Thames is just next
door the water was not going to
stop,” says Bradshaw
Initial grouting was just
washed out and a programme of
minipiling between buttresses
and shafts was devised to form
a grout curtain to cut off the
flow while the cross passage was
completed. On the other shaft,
forewarned, the grout curtain
was created before any trapped
ground water was disturbed.
Meanwhile inside the smoke
vent a series ofVictorian cast iron
struts needed upgrading. Two
levels of three rather elegantly
shaped struts, with flared ends,
had to be replaced. Architec-
tural heritage considerations
dictated that the replacement
struts should resemble the origi-
nals as far as possible. The upper
struts were removed completely
and new steel struts installed in
their place, but the lower struts
were more difficult because it
was hard to see exactly how they
connected at the wall.
Rather than risk displacing
anything the lower struts were
cut away in the centre and new
steel sections were inserted.
Around the remaining cast iron
lengths a sleeve was devised in
South of
the thames
new steel to take the loads. Apart
from the complexity of this work
the job was a major exercise in
logistics, with a crane at the top
of the shaft juggling old and new
pieces of steel around both the
permanent struts and three sets
of 250kN temporary props.
Marc and Isambard Brunel
had accessed their Thames
Tunnel works via a shaft on the
south bank of the Thames.
To make a lasting contribu-
tion to London’s engineering
heritage, BBCJV cast a whole
new floor in, sealing it off
from the tunnel and trains, so
leaving it available to the Brunel
Museum to develop as additional
exhibition space, including a
chance for visitors to see the orig-
inal shaft structure.
Other station work was also
complex.
“After contract award the client
decided to completely refur-
bish the station buildings and
platforms bringing them up to
modern standards; this devel-
oped into interior demolition
back to bare walls and even some
of those were reconstructed,” says
BBCJV stations project manager
PhilWharton.
Renewing bridges,
providing for
connections to the
mainline and future
London Overground
connections and a
flyover at New Cross
were big challenges
Excavation through
what had been
thought to be London
Clay instead turned
out to be rotten
timbers, possibly
from some long-
forgotten wharf
Depot: The South London site is a huge 90m by 40m steel framed structure
Whitechapel: Vital interchange
Hot stuff: Thermal welders at work Junction: The depot is just to the east of the massive New Cross Gate flyover
Wapping station: Orange temporary struts
brace the original 16m high buttress-and-coffer
brick retaining walls while the original struts are
replaced with new, stronger white lookalikes
9. 38 NEW CIVIL ENGINEER 27.05.10 | www.nce.co.uk
EAST LONDON LINE: SOUTHERN SECTION
The most complex part of
the operation to build the four
track crossing was placing the
main 1,200t Warren truss for
the 75m span. “Fortunately there
was some unused Network Rail
land alongside the mainline
tracks where our subcontractor
Fairfield Mabey could assemble
the bridge,” says Bradshaw.
To get it into position needed
a 56 hour possession, booked
long in advance.
“We used multi-axle self-
powered transporter units for
the move. The truss was jacked
at finished height onto trestles
on the back of the transporter
units and then moved south-
wards some 60m. Then one end
of the truss was slewed across in
a 60m long arc while the south
end took a shorter 20m long
path” says Bradshaw.
The construction yard
embankment area was previ-
ously surfaced with a 300mm
thick layer of recycled demoli-
tion aggregate to improve its
load bearing capacity for the
move.
To prepare the four mainline
tracks for the heavy loadings of
the bridge and its transporter
units, various bespoke level
crossing options were consid-
ered. But they would have been
expensive, not only because
a lot would have been needed
but they would have had to be
tailored to fit irregular track and
sleeper spacings.
Instead, a simpler solution
was found. By removing the
third rails that provide traction
power for trains in Network
Rail’s Southern Region and
protecting the running rails
with steel channel sections, it
was possible to build up a load
bearing platform using conven-
tional ballast. This meant it
was unnecessary to keep the
temporary fill and the existing
line ballast separate. Any surplus
would simply form part of the
railway afterwards.
“To get the flyover
into position needed
a 56 hour possession.
We used multi-
axle self powered
transporter units for
the move”
Andy Bradshaw, BBCJV
On the new viaducts and in the
tunnel, the East London Line
sees the first application of the
Sonneville boot system of slab
track.
For new viaducts and tunnels,
slab track was installed, using
the Sonneville system of concrete
blocks to support either end of
the sleeper, all embedded in a
concrete slab. Each independent
block sits on a neoprene pad inside
a rubber “boot” which dampens
vibrations; and the blocks can be
extracted and the boot renewed
easily when necessary. Noise
suppression was the key factor on
viaducts particulary as they run
through crowded areas of the city,
but reduced maintenance was the
prime reason for the choice in the
tunnels, where only night-time
access is possible.
“We had two variants of slab,
the basic one and in some places
the mass spring system,” says
BBCJV’s Steve Bradley who was
track construction manager for
three years of the project. The
difference lies in the concrete
surround for the blocks. Mostly this
is just mass concrete poured around
the booted blocks that are carefully
positioned by hanging them from
the precisely positioned rails that
have been placed inside a basic
concrete trough. But for additional
noise suppression on viaducts, the
trough is lined with an additional
absorbent membrane and the
concrete track slab poured around
it has to be reinforced to handle the
additional movement created by
the addition of the membrane.
The boot system is complex to
install, since each sleeper end is
independent and must be accurate
for rail inclination, gradient, gauge,
alignment and more, before fixing
in concrete. It is the first application
in the UK. Drivers have already
informally declared the line the
smoothest they have experienced.
TRACK
Big move: Four multi-axle transporters move the 1,200t Warren truss for the New Cross Gate flyover into position
Covering up: Temporary fill cover the track during the flyover move
Sound solution: Rubber “boots” under the track damp down vibration
Truss: Last minute adjustments
