The document summarizes a complex ground engineering project for the redevelopment of Crossrail's Paddington New Yard site adjacent to Paddington Station in London. Bachy Soletanche was contracted to install different pile types including 162 secant piles, 106 batching plant piles, 122 derailment piles, 77 low headroom piles, 74 SolThread piles, and 51 restricted access mini-piles. An innovative piling technique called SolThread was used, which requires less concrete and transport than conventional piles due to its threaded design. The SolThread piles increased capacity by 40% and formed the basis of facilities including a concrete plant, bus depot, and rail infrastructure at the site.

1. Crossrail C336 Paddington New Yard
Bored Piling
LONDON , U.K.
Scope of Works
162no. CSP secant piles, 106 no.Batching Plant
LDA piles, 122no. Derailment LDA piles, 74no.
SolThread piles, 77no. Restricted LDA piles
and 51no. restricted access mini-piles.
Introduction
Adjacent to Paddington Station, the redevelopment of
Crossrail’s Western Gateway, Paddington New Yard, is a
site that is steeped with historical interest. On this site the
team uncovered the foundations of Brunel’s’ engine shed
and two brick turntables dating to the 1800s – findings,
which in conjunction with a logistically challenging site,
have led to a complex ground engineering solution being
sought for the project.
Tasked with delivering specialist ground-engineering work
for the construction of derailment walls, bus depot and
batching plant, Crossrail and Costain appointed Bachy
Soletanche to the intricate project to deliver a unique piling
technique following a period of initial testing period.
Working alongside contractor Costain, Bachy installed162
CSP secant piles, 106 Batching Plant LDA piles, 122
Derailment LDA piles, 77 low headroom LDA piles, 74
SolThread piles and 51 restricted access minipiles,
operating in a head room of 5m. The low headroom Soiltek
rig operated in LDA rotary mode and had its mast reduced
to 9.3m to enable it to work safely under the A40 West Way
viaduct with, in places, a height restriction of only 10.36m.
The site team were keen to offer a more sustainable piling
solution, and so their design team proposed an innovative
technique to the project; following ten years of development
SolThread was delivered as a sustainable alternative to
conventional piles. Due to its threaded shape and design
SolThread requires less concrete to build the piles, and
less muck away lorries to remove pile spoil.
Rotary Bored Sol Thread Piles
A648
Secant piling, Rotary Bored piles,
Low Headroom piles, Mini-piles,
and SolThread piles
CLIENT: Crossrail
MAIN CONTRACTOR: Costain
CONSULTING ENGINEER: Capita
DURATION OF WORKS:
www.bacsol.co.uk
Sustainability Innovations
√ 1 Concrete savings using SolThread
threaded piles
√ 2 Reduced pile spoil and lorry movements

2. A648
“
The SolThread technique also offers financial and
environmental savings, in addition to a reduction in
site traffic and an associated improvement in safety
for road users. The aim of the development of this
innovative technique was the reduction of material
use and lorry movements compared to conventional
rotary piles through the creation of a threaded rotary
bored pile.
The process is based upon standard pile construc-
tion techniques with the addition of a stage to create
the thread on the pile bore. Remote access inspec-
tion techniques, based upon those for inspection of
under ream piles, are used to demonstrate the effec-
tiveness of the threading process, combined with
static load tests to validate the design assumptions.
Specially developed on-board electronic systems en-
able the operator to monitor thread formation and
provide as built record information.
www.bacsol.co.uk
Cased CFA Secant Piled Wall
This patented pile consists of a central core, with a
helical thread formed around this - increasing the
effective geotechnical diameter of the pile by
150mm. A pile with a threaded shaft also offered
increased skin friction compared with an unthread-
ed shaft and therefore increased pile capacity by
40% for the project. These piles form the basis of
the site’s facilities, which on completion will be
home to a concrete batching plant owner, a bus
depot, Crossrail running lines & turn backs, plus
sidings for freight rail operators, DB Schenker.
Low Headroom Rotary Piling under A40
The final phase of our works involved re-
stricted access minipiling. This involved
51no., 600mm diameter piles up to 20m
long and with a working height of only 5m,
underneath a elevated section of the A40
roadway. Some of these piles also includ-
ed I-beams, positioned to a tight verticality
and positional tolerance, for use as King
Posts retaining walls.Remote inspection of pile threads
Restricted Access Minipiles