The National University Hospital Medical Centre Project won a BCA Design and Engineering Safety Excellence Award (Merit) under the Institutional & Industrial Category, at BCA AWARDS 2014. By adopting innovative engineering solutions to overcome the site and design challenges, the structural works were completed and delivered on time, despite tight schedules, to enable commencement of other trades.

1. The Magazine Of
The Institution Of Engineers, Singapore
August 2014 MCI (P) 157/01/2014
www.ies.org.sg
THE
SINGAPORE ENGINEER
COVER STORY:
CIVIL & STRUCTURAL ENGINEERING
NUH Medical Centre
FEATURES:
Construction Technology • Health & Safety Engineering • Project Application

2. COVER STORY
NUH Medical Centre
The project won a BCA Design and Engineering Safety Excellence Award (Merit) under
the Institutional & Industrial Category, at BCA AWARDS 2014. By adopting innovative
engineering solutions to overcome the site and design challenges, the structural works
were completed and delivered on time, despite tight schedules, to enable commencement
of other trades.
NUH Medical Centre is the latest, and one of three buildings
serving hospital patients within the NUH campus. It houses 190
consultation rooms, more than 200 treatment and procedure
rooms, 10 day surgery operating theatres, as well as dedicated
space for teaching and clinical trials.
It is also home to the National University Cancer Institute,
Singapore (Yong Siew Yoon Wing) which provides one-stop,
comprehensive care for both adult and pediatric oncology
patients. The NUH Medical Centre is fully integrated with
infrastructure for support services, such as clinical laboratories;
14 THE SINGAPORE ENGINEER August 2014
facilities for dietetics services and imaging; pharmacy; and a health
resource centre, designed to provide patients with holistic care.
The 19-storey NUH Medical Centre was completed in 2013
and started serving patients in July the same year.
Generating a total GFA of 72,000 m2, the NUH Medical Centre
was a fast-track project completed in 28 months. The consultant
team was required to carry out thorough project planning,
design coordination and review of construction methodology,
to ensure engineering safety during project implementation as
well as timely completion.
NUH Medical Centre. Image by Penta Ocean Construction Co Ltd.

3. COVER STORY
August 2014 THE SINGAPORE ENGINEER 15
The main contract commenced on 16 December 2010.
T.O.P. was obtained on 26 April 2013.
As Structural Designer, T.Y. Lin International Pte Ltd (TYLI)
collaborated with the NUH Medical Centre’s consultant team,
drawing on TYLI Singapore’s expertise in engineering design
for healthcare structures and complex buildings, to develop
the optimum structural solution. The process encompassed the
consideration of both design and construction methodologies
for the structure. Er. Ng Swee Tong oversaw the project delivery
as the Project Manager and Qualifi ed Person.
PROJECT HIGHLIGHTS
A steel truss system was selected as the optimum structural
system for the facility. This incorporated six sets of double
steel transfer trusses located in between Levels 12 and 13.
The transfer truss system is a key feature of this project, as this
concept allowed the expansion of the Gross Floor Area (GFA)
to 72,000 m², by supporting eight additional fl oors over the
MRT station box.
There are six elevated radiation bunkers located on Level 8.
Each has a 2.5 m thick concrete enclosure.
The stringent requirement for radiation shielding demanded
effective temperature control of the large volume concrete
casting, so as to eliminate micro-cracking of the bunker
structures. The adequacy of the formwork system to support
the massive wet concrete during construction of these bunkers
was a key design consideration in locating the bunkers on
Level 8, for the operational effi ciency of the cancer centre.
SITE CHALLENGES
The NUH Medical Centre is located directly above Kent Ridge
MRT Station, within the fi rst reserve of the railway protection
zone and adjacent to the NUH Kent Ridge Wing in operation.
This presented a number of challenges that the team had to
overcome, for timely completion of the project.
• The undulating site terrain, with the existing ground levels
varying from 127.5 m to 141.95 m demanded careful design
consideration and planning.
• Mitigating the potential traffi c impacts throughout the
construction phase was crucial. The road network in the
vicinity of the hospital experiences heavy traffi c movement
especially during peak hours.
Development commencement and completion
Figure 3: Elevated radiation bunkers
LINAC bunkers formwork
The site plan

4. COVER STORY
• Rigorous control processes were considered at the design
stage and implemented stringently during construction, to
safeguard the structural integrity of Kent Ridge MRT Station
and the tunnels.
DESIGN CHALLENGES
The Kent Ridge Station structure was designed with provision
for a future building, with 24 column stumps on top of the
central zone of the station, that would house seven levels of
medical units. A difference in levels of 14 m at two sides of the
spiral ramp and the close proximity of the MRT tunnels posed
challenges in construction.
MRT station structure
16 THE SINGAPORE ENGINEER August 2014
The primary considerations in the selection of the structural
system for the healthcare facility included:
• Structural stiffness to meet the operational requirements of
various types of sensitive medical equipment.
• Building robustness to resist accidental loads.
• Ease of construction.
Special consideration was given to achieving high buildability
scores, despite the above stringent requirements.
CONSTRUCTION CHALLENGES
Heavy transfer structures are typically long-span and massive,
and they pose challenges for quality control during fabrication
and installation. As the site was in close proximity to the hospital
wards, mitigation of noise and vibration generated during
construction were essential, to avoid any inconvenience or
disruption to the hospital operations.
SITE SOLUTIONS
In anticipating various weathering grades of undulating rock
formation (from completely weathered to highly weathered
sedimentary rocks), extensive soil investigation was conducted
to map out the contours of rocks with SPT values greater than
100, for the entire site.
Structural system. Images by Penta Ocean Construction Co Ltd.

5. COVER STORY
August 2014 THE SINGAPORE ENGINEER 17
A total of 14 bore holes were completed for the site. With the
mapping of the rock contours, the pile design depths and socket
lengths could be predicted more accurately.
The site investigation revealed some areas with possible
existence of minor cavities in the limestone and these were
demarcated. Cavity probing and provision for grouting were
included in the piling contract, to detect the presence of fi ssures
or cavities, prior to the installation of bored piles.
Substantial earthworks for site formation were necessary before
commencement of the piling work and basement construction.
The installation of foundation and contiguous bored piles began
after the successful completion of two instrumented ultimate
load tests.
A total of 270 foundation bored piles and 537 secant bored
piles were installed. The bored piles range from 0.8 m to 2.2
m in diameter. The larger piles near the MRT station adit, with
plunge-in steel columns, were designed to facilitate the top-down
method of basement construction. To socket the foundation
piles into fresh rock stratum, in order to mobilise adequate skin
friction and end-bearing, BG-35 and BG-40 boring machines
were specifi ed in the contract.
Proper scheduling of construction works was done, with traffi c
diversions deemed necessary, to ensure there was no disruption
to the traffi c fl ow along Lower Kent Ridge Road.
To ensure no adverse effects on the structural integrity of
the MRT station and tunnels, a number of measures were
incorporated into the design and construction phase, including
real-time monitoring within MRT tunnels. In addition to installing
seven clusters of monitoring instruments, extensive ground
settlement points were identifi ed and monitored on site by an
independent specialist contractor during the construction.
In compliance with LTA’s requirements on railway protection
during construction, the stress effects due to excavation and
piling work carried out were assessed.
Boring machines
Stress changes

6. COVER STORY
Estimated movements. Images by Penta Ocean Construction Co Ltd.
18 THE SINGAPORE ENGINEER August 2014
• All movements
within limits
• Justifi ed that
90% of bored
piles within
MRT reserves
need not be
de-bonded.

7. COVER STORY
August 2014 THE SINGAPORE ENGINEER 19
The results indicated that the stresses induced were within
the allowable limit of 15 kN/m², as per the LTA specifi cations.
Real-time monitoring instruments were installed in the north-and
south-bound tunnels. The MRT tunnels were found to be
safe and the track alignment was not affected during piling and
basement construction.
DESIGN SOLUTIONS
Special consideration was given to the development of the
structural systems to meet the robustness criteria for the
building, in order to prevent disproportionate collapse under
accidental loads.
The structural design options were determined by the
performance requirements of the vital operational facilities of
the hospital, including the delivery paths of medical equipment,
the structural stiffness for stringent control of vibration of
sensitive medical equipment and the need for radiation shielding.
The steel truss system was the optimum structural system in the
design of the transfer structure. The design took consideration
of effi ciency in fabrication and installation of the trusses, the QA/
QC procedure and the reduction of the Concrete Usage Index
(CUI), for sustainable construction.
The slab at Level 11 was checked for the construction loads of
the temporary platform and construction equipment.
The transfer structure allowed a column-free space at Level 11
under the trusses for high fl exibility in layout confi guration.
CONSTRUCTION METHODOLOGY
A difference in levels of 14 m at two sides of the spiral ramp
and the close proximity of the MRT tunnels posed challenges in
construction. The top-down construction method was adopted
in the design, to eliminate extensive strutting or ground anchors.
This provided better control of ground movement during
excavation. The design provision with plunge-in steel columns was
implemented by the piling contractor. The same method was also
used for basement excavation next to the MRT adit structure.
Transfer structure. Images by Penta Ocean Construction Co Ltd.
Design of 11th storey slab Level 11 layout confi guration

8. COVER STORY
Top-down construction methodology
Spiral ramp
20 THE SINGAPORE ENGINEER August 2014
Top-down Construction

9. COVER STORY
All images by T.Y.Lin International Pte Ltd,
unless otherwise stated.
August 2014 THE SINGAPORE ENGINEER 21
The 2.5 m thick bunker slabs at Level 8 were cast in seven layers,
using ice, water and cement replacements, for effective control
of the peak and differential temperatures. Additional protective
measures were taken, in case of adverse weather during the
curing process.
CONCLUSION
The adoption of an innovative approach and in-depth design
with appropriate construction methodology, was essential
to overcoming the site constraints and design challenges. The
design considerations encompassed structural safety, buildability
and sustainability.
An effi cient and cost-effective structural system and team effort
during the construction stage, as well as a strong safety culture
shared by all project team members, including the developer,
contractor and consultants, contributed to the achievement of
safety and excellence in engineering design and construction.
Construction work in progress
Level 8 radiation bunkers. Image by Penta Ocean Construction Co Ltd. Casting sequence and thermal insulation
PROJECT CREDITS
Qualifi ed Person
Er. Ng Swee Tong
C&S Consultant
T.Y. Lin International Pte Ltd
Builder
Penta-Ocean Construction Co Ltd
Developer
National University Hospital (Singapore) Pte Ltd
Architectural Consultant
Consultants Incorporated Architects + Planners
CORRECTION
With reference to the news article ‘Er. Dr Tan Guan
receives Lifetime Achievement Award from ACES’,
that appeared on Page 48 of the June 2014 Issue of
‘The Singapore Engineer’, T.Y. Lin International Pte Ltd
wishes to clarify that whilst Er. Dr Tan was the Project
Director for the project, Er. Ng Swee Tong was the QP
and Project Manager.