The BT Tower - Lift Replacement for the 21st Century
	"This 1960's building typified the dreams of many people, standing as it did for the ideals of the new technological age. It was packed with the 'best of British'." Photo © Elevator World 2000.
| Exit | Sixties Specs | Nineties Survey | The Replacement Lifts | The South Car Flight Deck | Specialist Contractors |

Ove Arup R&D was chosen as the lift consultant to oversee the whole project with the aim of

• Making the elevators more reliable.
• Improving the ride comfort.
• Providing a memorable experience for visitors, thus adding to the excitement of attending a corporate event at "The Tower"  - a famous landmark and indeed a special honour to visit.

Sixties Specs

The original specification was for 2 lifts, each to carry up to 15 persons or a load of 2,250 pounds in a car 6 feet, 3 inches deep by 4 feet, 6 inches wide through a doorway of 3 feet, 6 inches wide by 7 feet high.

To transport the following:

• The public to the high-level observation floors.

• Customers to the high-level restaurant.

• Staff to the public floors, restaurant and kitchen.

• Kitchen supplies.

• Post Office Staff and visitors to the operational floors and aerial galleries.

• Aerials & equipment to the aerial galleries.

• Equipment racks to the operational floors.

• Maintenance staff and their equipment to all floors.

Sixties Staffing

Visitors to the Tower would once have been welcomed by:

• 2 Supervisors.

• 11 Administrators.

• 16 Souvenir shop & ticket desk staff.

• 32 Uniformed attendants.

The Lift Specification

A special feature was the removable ceiling giving an increase in height from 7' 9" to 12' when necessary to accommodate large aerial sections. Serving 30 floors the lift was designed to run at 1000 feet per minute, making a journey time from the 1st floor public entrance to the high-level galleries of about 40 seconds. This was the highest speed lift in the UK.

The driving sheave of 38" diameter and 13" wide was mounted directly onto the 90 horsepower d.c. motor without the use of reduction gears. Each lift was suspended by 6 double wrapped steel-wire ropes and the system was balanced by the use of compensating ropes between the counterweight and the bottom of the car.

Nineties Survey & Initial Planning

To quantify the work required a number of surveys were carried out:

• Ultra-scans of the concrete structure, to locate the reinforcing steel and any hidden obstructions.
• Data regarding the noise and ride were recorded for later comparison with the completed project.

It was quickly realised that to meet the new specifications, within the stringent time and budget restrictions, complete replacement, rather than refurbishment would be necessary. However, this would give the specified 20 to 30 year life together with the added advantage of greater reliability and longer term maintenance savings.

'The Tower is the only building in the country which is allowed to be evacuated by lift and, for this, Parliamentary legislation had to be passed.'  

Originally, much of the Tower was filled with Strowger switchgear, which occupied 17 apparatus floors. Nowadays, to fully utilise the empty floors, if more office space is provided with more people, then a reliable lift service is essential in providing a safe working environment.

To this end, a five-minute building evacuation has to be met, thus the lift speed is critical in achieving this new profile.

Lift speeds

• The existing lifts were designed to operate at 1,000 feet per minute.
• This was increased in the 1980s to 1,200 feet per minute
• The computer indicated that a speed of 1,400 feet per minute was possible within the limitations of the pit depths and overruns.

Arup fire developed a revised evacuation strategy as part of the 'total solution'.

The New Specifications

Work was focussed on 3 key areas:

Doors & Door Drive

• Replacement of the landing door systems to achieve a two-hour fire rating as required by the authorities.

System Controllers

• A new system to improve the aerodynamic stability of the lift car at high speed.

The Riding System

• New rails and brackets at 2.5 metre pitches.
• Roller guides of 300 mm diameter.
• Aerodynamic cowlings for the car.
• All components that would enhance the end ride quality.

The Replacement Lifts

Project Management

The contract for the new cars was awarded to Thyssen Lifts. However, as most  new work on the Tower is 'project managed' a 'briefing day' was called by Arup, the overall contractor responsible. This allowed all interested parties to meet up and give a co-ordinated approach to the work on hand...

• The client (BT) gave an introduction to the project with a reminder that the Tower would remain operational throughout and stressed the need to minimise any disruption to normal working.
• The consultant (Arup) explained why certain designs had been chosen.
• The safety officers highlighted the potential hazards and re-iterated the expected working practices.
• The project time scale and critical path were introduced to all groups, giving them a chance to raise any concerns.

The briefing essentially brought everyone together and generated enthusiasm for what was to be a complex project.

Planning

Time, budget and practicalities dictated that the existing lift shaft and motor room equipment would need to be removed and replaced in it's entirety. Refurbishment or overhaul of the original lifts was not an option-the 'swinging sixties' cars were destined for the scrapheap, to be replaced with a more spacious 21st century design having a height of 3.7 metres (approx 12 feet).

Arup structural engineers

• designed special load-spreading structures for the new drive units and landing cill supports.

Arup electrical engineers

• specified and supervised the replacement MICC ( Mineral Insulated Copper Cables) cables.

Execution

The massive (sixties designed) gearless machines had to be thermic lanced into small enough pieces so that the one remaining lift could safely handle the weight. For the liftmen and engineers whom had once maintained similar machines, this was a sad day. Of course, the new machines were to deliver a better quality ride, but this was little consolation for destroying what was once lift technology on a grand scale.

Removal of the old fixtures and fittings revealed deficiencies in the design...

The car guide rails were rigidly pinned to each fixing point. This meant that there was little (give) flexibility in the rails as the lifts moved over them. Additionally, for the length of the Tower, the building itself was subject to some slight (vertical) settlement and over the years this had severely distorted the guide rails, giving a poorer quality ride. Equally though, overhaul of the entire system was long overdue.

Design features of the new system...

• Operating speed of 7 metres per second.
• Aerodynamic shaft with air flows and displacements kept to a minimum.
• The trailing cable is sited in a channel running the whole length of the shaft.
• The landing door gear is hooded to provide cleanest air passage.
• High quality guide rails and car rollers- perfectly fixed, plumbed and aligned.

Final alignment of the guides throughout the length of the building was crucial to achieving a smooth ride quality.

The New Lift Cars

At 3.7 metres, these are among the tallest single-decker cars in the UK. Full assembly at Thyssen's Nottingham factory was not feasible, so the streamlined cones, top and bottom, were transported directly to the Tower.

John Gale, correspondent for Elevator World writes about Car Interior No. 1 (Sky Flight)...

"The interior finishes of this car certainly add a sky-like atmosphere to the journey, along with a crisp, clear, spatial sparkle. This was achieved by the use of optical white glass, which does not have that green tint to it, and 16 fibre-optic down lights. The modernist feel in the lift car is continued by the use of flat-screen indicators, special glass touch key pads and a laser-cut Tower graphic with blue LED position bars."

By November 1999, tests on the north lift proved more than satisfactory and the project moved onto Phase 2...

The South Car Flight Deck

When the management of Light Straw visited the Tower on 19th October 2002, Car Interior No.2, the south lift, operated by Dave Lemm, was fully completed. When the doors open, the bright lights really do give a feeling of spaciousness adding to the anticipation and excitement of being almost instantaneously transported to the very 'topofthetower'. Indeed, were it not for the announcement stating that you are travelling at over 1000 feet per minute, you could be forgiven for thinking that the lift was still stationary, such is the smoothness of the ride. And the high tech gadgets, such as the floor and speed indicators, add to the fun factor, making this more than just a simple lift ride. Photo © Light Straw 2003

Specialist Contractors

Liftout Ltd

"Having discussed contract requirements in detail with the client, our quotations are economically costed and then confirmed following a full site survey. Health & Safety Policy, Risk Assessments and a full Method Statement are supplied on receipt of order and Plant Test Certificates are always made available for on-site Health & Safety File."

Using Thermic Lance cutting equipment, Liftout’s highly qualified engineers set about the task of cutting through the massive 300 mm shaft of the old lift machinery. The bulky mass of the redundant gearless machines soon became manageable and was transported safely in small pieces to the ground.

www.liftout.net/

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Critical Path

Critical Path Method or Critical Path Node is a British idea that was devised in 1957 by the research department of CEGB (Central Electricity Generating Board). In America, a similar process was not adopted until 1958.

Critical Path charts & diagrams (rather like a graph) give an indication as to the latest times that certain activities need to be completed to ensure that the overall project is finished on time (and often budget).