With lifts and escalators used by millions of people every day in the UK, ensuring their ongoing safety is crucial. Hence the raft of regulations, standards and guidelines that exist to ensure they remain highly dependable modes of transport – while also safeguarding the well-being of the engineers tasked with maintaining such equipment.
These rules and regs have been covered comprehensibly in Operations Engineer over the years and will continue to be, especially as they are updated and/or superseded.
For the purposes of this article, however, the focus is on one high-profile lift project in particular that delivered an outstanding solution to a complex challenge, while fulfilling all of the critical safety requirements. To say this project had lofty ambitions would be appropriate and accurate.
Only those who have experienced the challenge of walking up the 334 narrow, ancient steps from street level to the top of the Elizabeth Tower – the world-renowned historic landmark, part of the Houses of Parliament in Westminster and home to ‘Big Ben’ – would know exactly how lofty and how ambitious.
But first, the back story. For many decades, the 165-year-old tower had been displaying signs of age and exposure to pollution. That was the catalyst for the first complete restoration of the tower from top to bottom in 2017.
Sir Robert McAlpine Special Projects (SRM), appointed main contractor, had to repair the building’s external fabric, renovate the clock, improve internal areas, add energy-efficient lighting and oversee the installation of the two lifts that are under the spotlight here.
LIFT-OFF
Prior to 2017, the only way to reach the top of the tower was by walking up the narrow spiral stone staircase.
“The 334 steps have posed a daunting deterrent for clock keepers and the lack of lift access meant that it was extremely challenging for maintenance teams to carry equipment and parts up to the belfry,” explains John Newbold, director at SVM Associates (independent lift consulting engineering firm).
An existing ventilation shaft measuring just 4.9m by 2.4m ran from the base of the tower to the belfry at the very top.
“The challenge was to design a lift that would fit into this extremely narrow ventilation shaft, which had not been accessed since the tower’s original construction in Victorian times,” they point out.
“Not only did the teams have to contend with very restricted space and limiting any intrusion into the fabric of the building, but the whole tower has a slight lean of 0.23 degrees to the northwest.
This means that the top of the tower is out of alignment by 0.22m, which was a crucial consideration for the design team, who had to work with millimetre clearances.”
The complex and precise engineering of the lift project required close collaboration between Stannah and SVM Associates, which has overseen lifts on behalf of Parliament’s Strategic Estates since 2013
SVMA’s role in the Elizabeth Tower lift project included lift and platform design, technical tender evaluation, involvement with design development and technical quality control.
Dave Saunders, head of major projects division at Stannah Lifts (lift supplier), notes: “Due to the site complexity, this was a task for Major Projects, our specialist division that works on technically complex or long-period construction projects, typically in heritage sites or infrastructure.
“The role performed by Stannah’s major projects division included detailed manufacturing design of the lift and platform, installation, commissioning and lift warranty maintenance.”
CUSTOM-BUILT SOLUTIONS
Within the 11.7m2 ventilation shaft space, a bespoke energy-efficient, gearless, traction-drive passenger lift was built.
The 13-person lift is contained within its own structural skeleton to minimise any penetrations into the building’s historic fabric,” explain Saunders and Newbold.
“The engineering interface between the new lift equipment and the existing historic features of the ventilation shaft, such as the original Victorian tie-rods, has been designed and installed with millimetre tolerance.”
The physical constraints of the tower mean that the main lift stops two floors below the belfry. From here, along a narrow corridor, neatly tucked into incredibly limited space, a smaller 500kg hydraulic lift platform services the final 4.3m between the last two floors and gives lift access to the belfry.
“Due to the belfry environment, the lift has been built to an external specification with 316-grade stainless steel and hot-dipped galvanised steel, chequer plate floor and IP54-rated buttons.”
The main lift travels 57 metres from the ground to the 11th 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,” add Newbold and Saunders.
“The 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.”
ENERGY-EFFICIENT
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.”
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.
MAINTENANCE-FREE
As for maintenance, the lift’s machinery is housed in a conventional motor room, 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 maintenance-free,” they confirm. “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.”
Newbold adds: “The passenger lift is an essential modernisation component of the overall restoration project. 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.”
Saunders says this exceptional engineering project was made all the more challenging by site restrictions, due to the COVID pandemic and stringent security requirements.
He concludes: “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 – which we achieved.”
BOX: SHINING DIAMOND
The neo-gothic Elizabeth Tower was officially unveiled in 1859 during Queen Victoria’s reign, declared a UNESCO Heritage Site in 1987 and given its current name in 2012 to mark Queen Elizabeth II’s Diamond Jubilee.