Issue 44 winter 24 - Journal - Page 21
The main lift travels 57 metres from the ground to the
eleventh floor and has a top speed of 1.5 metres per
second. The lift car has strengthened, hard-wearing walls
and floors to ensure it can be used for maintenance goods
as well as passengers.
Despite the many overriding constraints of building lifts
within the 160-year-old iconic structure, everything possible has been done to provide the best level of step-free
maintenance access from the ground floor to the top of
the tower.
The horizontal ride quality of the lift meets or surpasses
the British Council for Offices Specification Guide’s requirements for passenger lifts, which is a testament to the
lift’s precise manufacture, alignment, and accurate installation, particularly the guide rails. Furthermore, the lift
drive machinery is located away from the top of the shaft
so as not to disrupt the BBC’s live recording of Big Ben’s
chimes.
“The installation of the lifts in the Elizabeth Tower
restoration project has been a true feat of precision engineering and ingenuity,” said Nick Sturge, Project Manager, Sir Robert McAlpine Special Projects. “This project
was enhanced by the diversity of skills and trades that
made it possible and had a clear focus on sustainability,
championing the use of energy-efficient technologies.”
“The passenger lift is an essential modernisation
component of the overall restoration project,” said John
Newbold, Director at SVM Associates. "These UK-designed and made lifts will ensure improved access for
maintenance crew for many years to come, bringing a safe
and much-needed alternative to the 334 steps, especially
in the event of a medical emergency."
The Elizabeth Tower passenger lift also has a multitude of
advanced energy-efficient features. For instance, the regenerative drive acts as a generator whenever gravity assists the lift, thereby returning power back to the mains.
The mass of the counterweight is optimised to match the
likely load in the lift car, thereby saving energy, and when
it is idle, the lift also turns off its non-essential power loads.
“This was an exceptional engineering project, made all
the more challenging by site restrictions due to the
COVID pandemic and stringent security requirements,”
said Dave Saunders, Head of Major Projects Division at
Stannah Lifts. “In addition, the high profile of the Elizabeth Tower means that the eyes of the world were on us
to deliver this project on time and on budget. At Stannah,
we are always true to our word – we go the extra mile to
deliver something we can be proud of for years to come.”
www.stannahlifts.co.uk
The ropes' pulleys are made from polymer rather than
steel, so they are lighter and have less inertia. This makes
them easier to spin and, thus, more energy efficient. Lastly,
the lift is driven directly by a motor without a traditional
gearbox, thereby reducing power losses from mechanical
inefficiency.
Additionally, the lift incorporates all of the accessibility
features required of new lifts, including controls, dimensions and enhanced audio-visual passenger information.
Dual power supplies to the lift enable passengers to vacate
safely if required, even if the mains power is cut off.
As for maintenance, the lift’s machinery is housed in a
conventional motor room, thereby enabling maintenance
personnel to access the machine and control equipment
readily and safely. The lift also features advanced technology that ensures maintenance downtime is kept to a
minimum. Mechanical systems, such as machines, pulleys,
and compensation systems, are virtually maintenancefree. The individual rope tension is monitored by electronic transducers. Service engineers are notified when
rope adjustment is required, thereby prolonging rope life.
The control system is also equipped to regularly report its
status and performance to a remote monitoring system.
Designed safe for improved accessibility
The result of this incredibly complex and challenging
project is energy-efficient and precisely engineered lift systems that will make the work of the clock engineers significantly easier and could one day save lives in a medical
emergency – all while preserving the historic environment
of the clock tower. The designers, installers, and construction teams, all of which are UK-based, have inclusive and
sustainable employment practises that have given a range
of skilled workers a chance to work on returning a British
cultural icon and symbol of democracy to its former glory.
Above, the lift structure was placed to minimise damage to
Elizabeth Tower's brickwork
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Conservation & Heritage Journal
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