Modern cities extend in two directions that were once impractical: upwards into towers of a hundred storeys or more, and downwards into tunnels carrying trains, roads and services beneath streets that stay open above them. Neither direction was opened by a single invention. Tall buildings needed safe lifts, structural frames and cheap steel to arrive together, along with foundations that could reach solid ground through mud and water. Tunnels needed machines that could excavate and line a tunnel continuously without disturbing the buildings above.
The history of building up and boring down offers lessons that apply well beyond construction. It shows how a product’s value can wait on complementary technologies that someone else must develop, why trust in a new technology must be engineered and demonstrated, why it is sometimes better to decouple a system from a hazard than to strengthen it, and why hazards that cannot be eliminated need a designed route to safety.
This article traces the development of the safety lift, the skeleton frame, deep foundations, wind engineering, tunnelling machines and earthquake isolation, including examples from Australia and New Zealand, and then draws out lessons for engineers, product developers and business leaders. It is general information, not design guidance for buildings, lifts or tunnels.
The lift: selling safety, not height
Hoists using ropes, drums and counterweights had existed for centuries, but few people would ride in one. A rope is a single point of failure, and if it breaks the car falls. No improvement in rope quality changes that.
Elisha Otis addressed the failure itself. In the Otis safety device, tension in the hoist rope held a spring-loaded mechanism clear of toothed guide rails. If the rope lost tension, the springs drove pawls into the rails and stopped the car. At the 1854 exhibition in New York’s Crystal Palace, Otis demonstrated it dramatically, standing on a raised platform while the rope was cut and the platform held. The first passenger lift using the device was installed in a New York store in 1857. In 1880, Werner von Siemens demonstrated an electric lift in Germany, and electric drives later replaced steam and hydraulic power.
The device is a pure example of fail-safe design: the failure of the primary system triggers the protection. Modern lifts add several independent layers, including multiple suspension ropes, an overspeed governor that operates safety gear on the rails, limit switches at the ends of travel, buffers in the pit and door interlocks that prevent the car moving unless every landing door is closed and locked. In Australia, lifts are designed, installed and maintained to the AS 1735 series of standards, and lifts are generally among the plant items that must be registered under work health and safety laws.
Most traction lifts also use a counterweight roughly equal to the car’s weight plus about half its rated load, so the motor only has to overcome the difference. Balancing the load before powering it reduces motor size and energy use more than any improvement in the drive itself.
Otis’s demonstration matters as much as the mechanism. People did not adopt lifts because they worked; they adopted them because they believed they would keep working. Trust was an engineering deliverable, and it had to be shown, not merely claimed.
The frame and cheap steel
In a masonry building, the walls carry the load, so the walls at the base of a tall building must be very thick, consuming the floor space they enclose. A skeleton frame of iron or steel carries the load instead, and the outer walls carry only themselves. Chicago’s Home Insurance Building of 1885, designed by William Le Baron Jenney, is often cited as the first tall building with a load-bearing metal frame.
A steel frame is economic only when steel is cheap. The Bessemer and open-hearth processes, and later the basic process that allowed phosphorus-rich ores to be used, made structural steel affordable in the late nineteenth century.
Tall buildings needed three conditions together: safe lifts, because people will reliably walk only four or five storeys; the frame; and cheap steel. Each came from a different industry. Once all three were in place, the limit on height became largely economic rather than structural. As a building grows taller, more of each floor is taken up by lifts, stairs and services serving the floors above, until an extra storey adds less lettable space than it consumes. The Empire State Building, completed in 1931, held the record as the world’s tallest building for about four decades.
Foundations: the problem nobody sees
A tall building concentrates an enormous load on a small area of ground. Many cities where tall buildings were wanted sit on river deltas, reclaimed land or soft deposits, where solid rock lies beneath waterlogged material that flows back into any excavation.
The pneumatic caisson solved this. A working chamber, open at the bottom and sealed at the top, was filled with compressed air to hold back water and soft ground while workers dug beneath it. The caisson sank as material was removed, and when it reached bedrock it was filled with concrete to become a foundation. Caissons were used for bridge piers and, from the 1890s, for tall buildings in New York.
Caisson work had a severe human cost. Returning too quickly from compressed air to normal pressure causes decompression sickness, which was poorly understood at the time. On major bridge projects of the 1870s, including the Eads Bridge at St Louis and the Brooklyn Bridge in New York, workers died or were permanently disabled, and the Brooklyn Bridge’s chief engineer, Washington Roebling, was also left seriously ill. Modern rules on exposure, staged decompression and medical supervision exist because of what happened to those workers.
Wind: the load that grows with height
For a low building, wind is a modest load. For a tall one, it often governs the design. Wind speed increases with height, and the overturning effect at the base grows with the square of the height even under uniform pressure, and faster still because the upper floors face stronger winds. Tall buildings therefore need dedicated systems to resist sideways loads, from the bracing of early skyscrapers to stiff cores, outrigger structures and tuned mass dampers.
Tall buildings also face a subtler effect. Wind flowing around a building can shed swirling vortices alternately from each side, pushing the building from side to side. The Burj Khalifa in Dubai, completed in 2010 at more than 800 metres, was shaped with setbacks so that its cross-section changes with height, preventing the vortices from organising into a strong, regular force. Engineers tested its shape extensively in wind tunnels. Changing the shape removed the problem at its source rather than resisting it with more structure.
Boring down: tunnelling machines
In 1825, Marc Brunel began the Thames Tunnel in London using a tunnelling shield, a structure that protected workers at the face while they excavated and lined the tunnel behind them. Completed in 1843, it was the first tunnel known to have been built beneath a navigable river, and the shield principle underlies modern tunnelling. In 1845, Henri-Joseph Maus designed a mechanised rock tunnelling machine for an Alpine crossing; it did not succeed, but the idea of excavating mechanically and continuously, rather than by repeated cycles of drilling and blasting, proved right.
A modern tunnel boring machine is best thought of as a mobile factory that produces a lined tunnel. It:
- Cuts the ground with a rotating cutterhead.
- Supports the face in soft or wet ground, using pressurised spoil or slurry to prevent collapse and surface settlement.
- Removes spoil by conveyor or slurry pipeline, which often limits the rate of advance.
- Lines the tunnel with rings of precast concrete segments, grouting the gap between ring and ground.
- Pushes itself forward with hydraulic rams that thrust against the last ring it built.
- Steers using laser guidance, holding line and level to within tens of millimetres over kilometres.
The main purpose of bored tunnelling in cities is to keep the surface undisturbed. Cut-and-cover construction can be cheaper per metre but closes roads, diverts services and disrupts buildings along its whole length. Major recent rail and road projects in Sydney and Melbourne have relied heavily on tunnel boring machines for that reason. Because ground loss around the machine can cause settlement and damage at the surface, settlement monitoring with trigger levels and planned responses is central to tunnelling risk management.
The Channel Tunnel: engineering for the event
The Channel Tunnel between England and France, opened in 1994, follows a layer of chalk marl that is strong enough to stand, soft enough to bore quickly and nearly impermeable to water. The route is not the shortest; it is the one that stays in favourable ground. Tunnelling from both coasts, the drives met beneath the sea within a small margin, a triumph of survey as much as excavation.
Its safety design rests on three tunnels rather than two. Two running tunnels flank a smaller service tunnel, linked by cross-passages, and the service tunnel is kept at higher air pressure so smoke cannot enter it. When a fire broke out on a freight shuttle in 1996, the train and part of the tunnel lining were severely damaged, but everyone on board escaped through a cross-passage into the service tunnel. The design had not assumed fire would never happen. It assumed that when it did, people would need a protected way out.
Decoupling from earthquakes
The conventional way to resist earthquakes is to make a structure strong and ductile enough to survive the shaking, accepting damage while preventing collapse. Base isolation takes the opposite approach: reduce the forces entering the building by separating it from the ground.
In New Zealand, Bill Robinson developed the lead-rubber bearing, which combines layers of rubber and steel, flexible sideways but stiff vertically, with a lead core that absorbs energy as it deforms. The William Clayton Building in Wellington, completed in 1981, was the first building to sit on such bearings, and later buildings including New Zealand’s Parliament Buildings and the Te Papa museum also use base isolation. Isolation lengthens a building’s natural period of vibration, moving it away from the frequencies where earthquake shaking is strongest, so the building moves gently on its bearings rather than shaking through its height.
Isolation protects contents, equipment and ceilings as well as the structure, which is why it suits hospitals, data centres and other facilities that must work immediately after an earthquake. It also requires a clear gap around the building and flexible connections for every service crossing the isolation plane.
Construction method shapes design
In many modern structures, how something will be built drives its form. France’s Millau Viaduct, opened in 2004, crosses a deep valley where scaffolding from the ground would have been impractical. Its steel deck was assembled on the plateaus at each end and pushed out over the piers by hydraulic jacks, with temporary supports reducing the spans during launching. Each part of the deck passed over the supports during launching, experiencing loads quite different from those in service, so the temporary condition shaped the design. The what engineering failures teach a business article discusses why temporary conditions and fail-safe design matter so often.
Lessons for product and business leaders
Value can wait on complementary technologies
Tall buildings needed lifts, frames and cheap steel together. A new product or service may depend on enablers that others must develop, such as infrastructure, standards, components or customer skills. Identify those dependencies and their timing before betting on adoption.
Trust must be engineered and demonstrated
Otis sold safety, not height, and demonstrated it publicly. New technology in a workplace or market is adopted when people believe it will keep working. Demonstrations, transparent testing and visible safety features are part of the product.
Make failure trigger protection
Design systems so that losing the primary function, such as power, tension, pressure or a signal, moves them to a safe state.
Decouple rather than strengthen
Base isolation reduces forces instead of resisting them. Isolating sensitive equipment from vibration, separating processes that interfere with each other or buffering between operations can be cheaper and more effective than strengthening everything.
Remove problems at their source
Shaping a tower against the wind removed a load rather than resisting it. Look for design changes that eliminate a problem before adding capacity to cope with it.
Let the ground choose the route
The Channel Tunnel followed favourable geology. Investigate the conditions a project must work in before fixing its design.
Plan for the event you cannot prevent
Where a hazard cannot be eliminated, provide a protected way out, a fallback or a recovery plan, and test it.
A worked example
This is an illustrative example. A precision component maker is moving into a new factory and will install a large press and a coordinate measuring machine (CMM) that must measure parts to within a few micrometres. It is also introducing an automated loading cell that operators are wary of.
Investigate the ground. A geotechnical investigation finds soft fill beneath part of the site, so the press is placed where the ground is better and given its own foundation, designed by a structural engineer.
Decouple rather than strengthen. Vibration from the press could disturb the CMM. Stiffening the whole floor slab is estimated at about $150,000. Instead, the CMM sits on a separate isolated slab with vibration-isolating mounts in a temperature-controlled room, at an estimated $30,000, and the room is placed away from the press.
Plan the path and the temporary condition. The press is delivered in sections. The installation plan checks crane positions and outrigger loads on the new slab, which can exceed anything the slab carries in service, and specifies outrigger mats and an exclusion zone. The planning the path from supplier to installation article covers this kind of planning.
Engineer trust. Before the loading cell goes into production, the integrator demonstrates each safety function to operators: opening a guard, breaking a light curtain and cutting power each stop the cell safely. Operators help write the procedures for clearing jams.
Result. The CMM meets its accuracy requirements, installation proceeds without damage to the slab, and the operators use the cell confidently because they have seen how it fails safely.
Applying these lessons in an Australian business
- Map the enablers a new product or technology depends on.
- Demonstrate safety and reliability to the people who must trust new equipment.
- Design for fail-safe behaviour when power, signals or supplies are lost.
- Isolate sensitive equipment rather than strengthening everything around it.
- Investigate site conditions before fixing layouts and foundations.
- Plan installation loads and access, which can exceed service conditions.
- Provide protected routes to safety for hazards that cannot be removed.
Questions worth considering
- Which complementary technologies or skills must exist before our new product delivers value?
- How do we show customers and staff that new equipment will keep working safely?
- What happens to our machines and systems when power or a signal is lost?
- Where could we decouple a problem instead of building more strength or capacity?
- Have we investigated the conditions our next project must work in?
Bringing it together
Building up and boring down became practical through combinations of technologies and through engineering that made new risks acceptable. The safety lift turned a fatal failure into a stopped car and earned public trust through demonstration; frames and cheap steel removed structural limits on height; caissons reached bedrock at great human cost; tunnelling machines protected the surface above them; and base isolation and the Channel Tunnel’s safety design showed the value of decoupling from hazards and planning for events that cannot be prevented. For businesses, the lessons are to map enablers, engineer trust, design for failure, decouple where possible and investigate before committing.
Source: KEVOS editorial notes, drawing on an earlier KEVOS engineering history series on tall buildings, foundations, lifts, tunnelling machines and modern civil works, together with established histories of engineering. The worked example is illustrative. This article is general information, not design guidance; buildings, lifts, foundations and tunnels must be designed by appropriately qualified engineers in line with applicable standards and laws.
