The Shard

The Shard, at 1,016 feet, is at the time of writing the tallest building in Western Europe. (The tallest in Europe is the Lakhta Center, Saint Petersburg, at 1,517 feet. There are four other European buildings taller than the Shard, all in Moscow.) Its 95 storeys replaced the 24 storeys of Southwark Towers (1975), one of the dismal buildings around London Bridge station that made the area rather glum - albeit historically interesting. 

Irvine Sellar, the developer of the Shard, who started his career selling clothes from market stalls, bought Southwark Towers in 1998, but it was to be ten years before construction of the Shard commenced. The original proposal was for a 1,400 feet tall 'pipe', with a corkscrew spire, designed by Peter Vaughan of Broadway Malyan, a dull design that, had it been built, would have been truly hideous. The Shard is properly uplifting architecture, designed by Renzo Piano, whose very first sketches were for a tapering spire of glass. 

Originally designated as London Bridge Tower, the Shard faced years of difficulties before it ever lifted from the ground, including intense resistance from those who thought insane the idea of constructing the UK's tallest building south of the river, from English Heritage, and from Historic Royal Palaces. It was a positive recommendation from a public planning inquiry that allowed the scheme to proceed to financing. 

The financing itself proved a headache. The 2003 planning permission required building to commence within five years. The recession of 2007/08 made it difficult to secure the necessary funds. A deal with Credit Suisse for the requisite £1.35 billion fell through at the last moment. It was the financing by the Qatar National Bank that ultimately enabled the Shard to be built. The State of Qatar now owns 95% of the development. 

The constructor was Mace - new to very tall buildings, as were Sellar and Piano - who agreed a £435 million fixed-price contract, itself unusual for such a project. Amongst the dozens of specialists, WSP Global acted as lead engineering consultants, Stent undertook the piling - 120 piles, three feet in diameter, driven 177 feet beneath the lowest basement level - and Byrne Bros. the concreting; whilst Severfield-Rowen provided the steel, Scheldebouw the glass, and KONE the lifts. 

Demolition of Southwark Towers commenced in April 2008, and construction of its replacement began on 16 March 2009. The Civil Aviation Authority had set a height limit of 1,000 feet. The Shard is, though, 16 feet taller than that, as it has a split-level base, and height is measured from a building's lowest above-ground level. The 801 feet tall core topped out in early 2011, and the structural work was completed on 30 March 2012. The formal opening ceremony was held on 5 July 2012. 

The building has a central concrete core, which resists twisting motions induced by the wind. 11,300 tons of steel went into strengthening this and shaping the tapering form. In a first for construction of a skyscraper, the core was carried upwards at the same time as the basement was driven downwards. The ground floor was cast first, the earth extracted beneath this, another slab cast, and so on down to the bottom of the third basement level, 42 feet below ground. The core was carried up 21 storeys before the lowest slab - 13 feet thick, 194,000 cubic feet of concrete, delivered by 700 trucks - was laid in just 36 hours. 

By this point the core was rising ten feet per day, absorbing 11,300 cubic feet of concrete diurnally, and the building as a whole was rising three storeys every fortnight. A crane atop the core was hydraulically jacked upwards as the build proceeded. This first crane built a second, cantilevered off the 55th level, which then dismantled the first. 

Unlike most skyscrapers, the Shard doesn't have a mass damping system. Instead, the floors below the hotel and residences are built in steel, and the habitable floors above in concrete, providing an inbuilt high-level mass. The tower has a sway tolerance of 16 inches. The 217 feet tall open spire, which forms the top 23 storeys, gives the Shard a feeling of blending into the sky, despite weighing 492 tons. It was test-built offsite before being built up from the upper deck of the observatory. The white steel frames are part in-filled with 516 glass panels, giving the top of the tower a feathered look. 

The eight façades, angled at six degrees to the vertical, are clad with 11,000 panels of glass, covering 602,800 square feet. This is of a special low-iron formulation, such that the building has a crystalline appearance - most skyscrapers have a green tint. The glass is also of the float, instead of the toughened, type, so what is reflected in it is crisp, not ripped. Finally, the glass is only 20% reflective, which makes the building look more permeable than most skyscrapers. Each panel, comprising an outer pane, a void within which sits an automatically-operated translucent blind, and inner double-glazing, weighs nearly a third of a ton. The blinds retract into red-orange boxes. 

The Shard is a mixed-use building, and has been described as a vertical city. The tower provides 4.3 million square feet of space, over 72 habitable floors. 26 floors are offices (3-28), three are occupied by restaurants (31-33), 19 are taken up by the Shangri-La luxury hotel (34-52), 13 are residential apartments (53-65), and six are in the form of the multi-storey observatory. This last extends from level 68 to level 72 - some of the spaces comprised of more than one storey - and attracts a million visitors annually. 

There are 36 lifts - 13 of the passenger varieties of which are double-decked, serving two floors at once - saving visitors the 306 flights of stairs. Automated detection systems in the circulation areas direct people to the lift that will get them to their destination most quickly. 

The Shard is part of a much wider redevelopment of the London Bridge area that includes two other buildings of which Sellar was the developer and Piano the designer - the News Building and Shard Place - and extensive re-modelling of the railway station, including a new concourse roof, also by Piano, and of the street-level environment. The area is now infinitely more attractive than it used to be, and despite all the early opposition the Shard is now very much London's adopted symbol.

New Southgate Gas Works

New Southgate is a largely residential suburb of North London that has portions in each of three London boroughs - Barnet, Enfield and Haringey. It broadly aligns with what used to be called Colney Hatch. 

The new name was adopted in order to distance the district from the lunatic asylum, built in 1851, with which Colney Hatch was once synonymous. There was little here until the arrival of the Great Northern Railway.

To the south of this was built, in 1858, the New Southgate Gas Works. The works ultimately included three gas holders, the largest of which (pictured) was built in 1912, hard by the North Circular Road (opened 1910, completed about 1930). 

The works closed in 1972, and the two smaller gas holders were dismantled. The remaining holder was decommissioned in 2001, but survived until 2020, when it was dismantled by Erith Demolition, for National Grid.

Falkirk Wheel

The Forth and Clyde Canal (built 1768 to 1790) and the Union Canal (built 1818 to 1822) were once linked by a flight of 11 locks at Camelon, near Falkirk, that carried the former 112 feet up to the latter. These fell into disuse in 1933. When the Millennium Link project set out to restore the two canals and rejoin the Clyde and the Forth, a task achieved in just three years between 1999 and 2001, a new means of connecting them was required.

The Falkirk Wheel, built 2000 to 2002, was the solution. The world's first rotating boat lift, the wheel forms part of a £20m complex comprising a 551 feet long tunnel that carries the Union Canal under the Antonine Wall, a 341 feet long aqueduct that brings this higher canal to the wheel, and the lift down to a large basin that itself gives onto the Forth and Clyde Canal. The site is just under two miles from the original locks, and was previously home to a redundant tar works.

The wheel itself is 115 tall and 89 feet long, and bridges 82 vertical feet between the two canals. Designed by Nicoll Russell Studios, of Dundee, it employs two interlinked mechanisms that serve to keep level the rotating gondolas, and the water and boats within them, whilst using the bare minimum of power. Just 1.5kW, about that needed to boil six kettles of water, is required to turn the wheel through 180 degrees, yet the transition takes just five minutes.

The first mechanism is the ten hydraulic motors that drive the axle, 13 feet in diameter, and thereby a central cog, 26' 3" in diameter, fixed to both the axle and the end support of the aqueduct. As the axle turns, smaller rotating cogs, either side of the central cog, transfer the drive to cogs mounted inside of the propeller-like arms of the wheel, one each side. These outer cogs rotate at the same speed as the central one, being the same size as this, but in the opposite direction to the axle and the wheel as a whole.

The second mechanism, a series of bogie wheels at each end of the 82 feet long gondolas, run on curved rails mounted within the propeller arms. Gravity largely enables this second mechanism alone to keep the gondolas horizontal, but wheel friction and sudden displacements within the gondolas could jolt these out of alignment. The non-powered mechanism of five cogs keeps everything safely aligned.

From boat entry to boat departure, the trip through the lift takes just 15 minutes. Once boats have entered/departed the gondolas, paired steel gates move from a prone position to an upright one, closing off the gondolas, the aqueduct at the top, and the basin at the bottom. Rubber seals spring out along the sides and bottoms of the paired gates and the water between these is pumped out. When the half turn is completed, water is pumped back into the space between the paired gates, which then flap downwards to enable boats to depart/enter the lift.

The speed, elegance and efficiency of the wheel belie its scale. The complete structure weighs in at 1,772 tons, of which 98 tons is in the form of the two gondolas, and 492 tons in the form of the carried water and boats. In accord with Archimedes' Principle, boats entering the gondolas displace their own weight in water, although a system of sensors, valves and bypass pipes maintain the water levels in the aqueduct and basin, so as to keep those in the gondolas consistent. There's a maximum variation in water height between the paired gondolas of three inches.

The steel fabrication was undertaken by Butterley Engineering, of Ripley. The structure is bolted together, not welded, to give it greater strength. 15,000 bolts were driven through 45,000 holes, the punched-out weight of which was just under seven tons. A joint venture between Morrison Construction, of Scotland, and Bachy Soletanche, of Ormskirk, acted as main contractor. The wheel itself, fabricated offsite, was erected in just six days.

Arup Consultants and Tony Gee and Partners acted as civil engineers. Much clever materials thinking went into the engineering. The elegant hoops that support the aqueduct, for instance, are of steel-reinforced concrete up to the point that carries the weight of the trough, but of GRP (glassed-reinforced plastic) above that. The canal engineers and navvies of old would be proud.

Verity

At 66' 5" tall, the statue Verity, which dominates the harbour entrance in Ilfracombe, Devon, is (apparently deliberately) 10 inches taller than Antony Gormley's 1998 Angel of the North. Yet whilst the Angel is uplifting, the truth of Verity is that although she's impressive in a monumental fashion, she's also unsubtle, obvious and brash, like most of Damian Hirst's work.

Weighing in at 24.6 tons, the statue was created in 2012. It is a variant of traditional representations of Justice, usually presented blindfold and holding aloft the sword of truth and holding out the eponymous scales of her calling. This Justice is pregnant. Whilst she brandishes the traditional sword, the scales are held behind her, at half cock.

Standing upon a tumble of law books, Verity is complete one side, but flayed and sectioned the other, the skull and foetus both visible. Both the representation and the stance, the latter supposedly a reference to Edgar Degas's c.1881 statue Little Dancer of Fourteen Years, are similar to those of Hirst's 2005 statue, The Virgin Mother.

The statue was cast, in multiple sections of bronze, which are affixed to a stainless steel frame, by the Pangolin Editions foundry of Stroud. The sword, and the upper part of the arm holding this, are of one piece of fibreglass. When installed the statue was the tallest in the UK, a record now held by Falkirk's The Kelpies. It has been loaned to Ilfracombe for 20 years.

Deflated Gas Holders

Gas holders, also incorrectly referred to as gasometers - they don't measure anything - were once a common sight in UK towns and cities. They provided a means to store gas, and to maintain the downstream supply at what is called district pressure.

The first gas holder in the UK was erected in 1798, at the Soho Manufactory, in Birmingham. The water-sealed telescopic form, which came to dominate, was invented in 1824, the first constructed in Leeds. The earliest telescopic holders had two lifts, supported by columns. Later models had up to four, frame-guided, lifts. In 1890 William Gadd, of Manchester, invented the spiral-guided gas holder, the helical runners of which obviated the need for an exoskeleton. The last of these was built in 1983.

The gas was stored at near atmospheric pressure, the necessary weight applied by the heavy cap. The tank containing the gas floated in a reservoir of water, which provided the necessary seal, and rose and fell as the volume of stored gas either increased or decreased. A lipped channel around the base of each lift picked up water from the reservoir as the gas holder rose, thus maintaining the seal.

The holders were often sited next to plants producing town gas from coal, but were steadily adapted to store natural gas. Typical volumes for the larger holders, up to 200 feet in diameter, were 1.8 million cubic feet. As a nationwide network of pressurized pipes and regulators for provision of natural gas was developed the holders increasingly became redundant. A few still serve to balance pressure in the pipe network, but in 2013 National Grid announced plans to steadily remove the gas holders of England and Wales. SGN has similar plans for those in Scotland.

The three gas holders visible from the Aston Expressway, Birmingham, were decommissioned between 2009 and 2011. The conjoined pair, erected in 1885, were once part of the Windsor Street Gas Works; sometime in the 1980s they were painted in the claret and blue colours of nearby Aston Villa Football Club. National Grid has been granted permission to demolish all three holders, which are expected to disappear in 2020.

(Second photograph by Abi Smith.)

Broen / Bron

The Øresund (Danish) or Öresund (Swedish) Bridge is a four-lane motorway and twin-track railway bridge that links Copenhagen and Malmö. The two-deck bridge at the Swedish end of the crossing is 4.9 miles long, and terminates on the artificial island of Peberholm, from where the 2.5 mile Drogden Tunnel runs to Amager, in Denmark. It is Europe's longest combined road and rail bridge. The tunnel was necessary to prevent interference with the flight path for Copenhagen Airport, and to provide a clear passage for ships and ice floes.

The bridge, the principal engineering design of which was undertaken by Ove Arup, was built by a joint venture between Hochtief (Germany), Skanska (Sweden), Højgaard & Schultz (Denmark), and Monberg & Thorsen (Denmark). Construction commenced in 1995 and was completed in August 1999, three months ahead of schedule, at a cost of c.€4bn. The official dedication took place on 1 July 2000. The bridge weighs in at 81,000 tons. The three cable-stayed sections together total 1,611 feet (a third of a mile) in length, and are slung from concrete towers 669 feet high, providing 187 feet of headroom for shipping. Otherwise the bridge is supported on concrete piers spaced at intervals of 459 feet.

Peberholm - Pepper Islet - so-called to partner the nearby natural Saltholm - is built from Swedish rock and the material dredged during construction of the bridge and, in particular, from the trench in which sits the tunnel. The island is 2.5 miles long and averages a third of a mile wide. On the island the train tracks emerge from the lower deck of the bridge and splay out to parallel the vehicular traffic. The Drogden Tunnel comprises 2.2 miles of immersed tube, in twenty concrete sections of 54,000 tons each, 125 feet wide, the largest in the world, plus approach tunnels of 886 feet each. Five side-by-side tubes accommodate two train lines, two lanes of vehicles in either direction, and services and emergency access.

(Photographs by Abi Smith.)

i360 - World's Most Slender Tower

Brighton's i360 'vertical pier' was conceived and designed by Marks Barfield Architects, the same team that was behind the London Eye, also sponsored by British Airways. It is sited at the landward end of the ruined West Pier. Built at a cost of £46m, the civil and structural engineering undertaken by Jacobs UK, it is Britain's tallest moving observation tower. At 531 feet tall, it mirrors the height of nearby Beachy Head. Aluminium wind-diffusing cladding aids a damping system in addressing the inevitable wind shear.

A significant portion of the structure is underground. 2,000 interlocking concrete piles were sunk about 65 feet into the underlying chalk bedrock to enable excavation for the foundations. Over 7,000 tons of shingle was removed, to a depth of about 20 feet, and the concrete base for the tower - over 4,000 tons of concrete reinforced by about 195 tons of steel rebar - built directly upon the bedrock. A precision-engineered 21.6 ton anchor bolt frame was set into the concrete.

The tower is formed of 17 steel tubes, fabricated in the Netherlands by Hollandia Infra BV - the main contractor. Delivered to the beach by barge, along with a jacking frame nearly 200 feet tall, and the counterweight for the pod, the tubes vary from about 15 to 39 feet in length, the shorter ones at the bottom. Their wall thickness reduces with height, to a minimum of just ¾ inch, giving a thickness to diameter ratio less than that of a can of beans. The first three tubes were lifted into place by crane, and bolted to the anchor frame. Four tubes were lifted into place atop the first three, and bolted together, but not to those beneath. The temporary jacking tower then lifted these four tubes, enabling a fifth to be slid in from below and bolted to those above. The final lift, of 13 conjoined tubes, was of about 965 tons. This 'top-down' method of construction obviated the need for a tower crane. Work commenced on site in July 2014, and was completed in July 2016, but the tower of tubes, joined together by 1,336 bolts, reached its full height in just ten weeks.

The tower is just 12.7 feet in diameter. With a height to diameter ratio of 41:1, it is the most slender in the world. It is all the more remarkable, thus, that the pod, suspended from eight steel ropes, is as large as it is. 59 feet in diameter, and weighing over 92 tons, this can carry up to 200 people. The oblate ellipsoid pod was designed and built by Pomagalski SA, the French cable car specialists, and ascends to 453 feet. It consists of trusses that cantilever off a central chassis. 24 solid floor sections sit atop the trusses, and atop those sit 36 glazed sections, 24 facing outwards, and 12 facing the tower. The double-laminated glass, which can't be cut once toughened, had to be first cut to shape before it was double curved at high temperature. The drive mechanism, housed in the basement, is akin to that of a cable car. The descent produces about half the power needed for the next ascent.

As part of the development the Italianate Victorian tollbooths that used to flank the entrance to the pier were reconstructed. The originals were designed by Eugenius Birch as an integral part of his pier of 1866. The western one had been demolished, and the eastern was structurally unsound. The latter was dismantled and detailed measurements were taken. Ductile cast iron mouldings - 24 tons of them - were made anew, by the Swan Foundry, of Banbury, so as to precisely replicate the originals. The western tollbooth is now the i360's ticket office, whilst the eastern operates as the West Beach Cafe & Bar.

Penang - Curtis Crest Treetop Walk

The Habitat is an area of conserved regrowth rainforest, cut down by the British to enable the building of bungalows in the cooler air atop Penang Hill. Its structural highlight is the Curtis Crest Treetop Walk, which opened to the public on 1 May 2017.

This 360-degree viewing platform, about 330 feet round, stands about 40 feet above the ground from which it springs. At 2,690 feet above sea level, it is the highest point in Penang, and provides a stunning view of both George Town and virgin rainforest.

The structure, which is cantilevered from a series of canted uprights that were designed to resemble chopsticks standing within a bowl, is named after the first superintendent of the Penang Botanical Gardens, Charles Curtis. Perunding YAA, of Penang, provided the structural engineering expertise.

Standedge - Longest, Deepest, Highest

The Standedge canal tunnel, on the Huddersfield Narrow Canal, is one of four parallel tunnels - the other three are railway tunnels - that run through the Pennine hills between Marsden, West Yorkshire, and Diggle, Greater Manchester. The Act of Parliament authorising the canal's construction was passed in April 1794. Benjamin Outram, acting as consulting engineer, estimated the total cost, including the tunnel, at £178,478, and the construction period at five years. Nicholas Brown undertook the necessary survey work, which foresaw a tunnel of 5,456 yards.

Outram was appointed site engineer, and Brown surveyor and superintendent. The tunnel was driven from both ends at once and from intermediate shafts. The intermediate workfaces were abandoned in the autumn of 1796. This change, greater water ingress than expected, and difficult geology, slowed progress. The rest of the canal was completed by 1799, and horses used to transship cargo over the Pennines between the completed sections. Tenders for work on the tunnel went unlet, and it was found that the headings had been driven several feet higher from the Diggle end than from the Marsden (above). In 1801 Outram resigned and Brown was dismissed.

In 1806 a new Act of Parliament provided for the raising of further finance. Thomas Telford was consulted, and in 1807 drew up a plan for completion. This corrected for the crooked workings driven from the intermediate headings: the tunnel has noticeable bends. Finally completed in March 1811, and at a cost of £123,803 for the tunnel alone, this was 5,445 yards (3.1 miles) long, 636 feet below ground at its deepest, and 643 feet above sea level. The longest, deepest and highest canal tunnel in the UK.

In 1822 the tunnel was extended 11 yards at the Marsden end, to accommodate reservoir works. In 1893 it was extended again, by 242 yards, this time at the Diggle end, so that the 1894 railway tunnel could be carried over it. These additions supposedly made the tunnel 5,698 yards long, although modern survey techniques make the total length 5,675 yards (3.2 miles).The tunnel has no towpath, which required the canal boats to be legged through. This was tough and dangerous work, not least given that large parts of the tunnel were left unlined, with the native rock jaggedly proud of the ever-changing overall profile. Some sections are lined with rough-dressed stone, and some with brick.

The Huddersfield and Manchester Railway bought the canal in 1846, which enabled the first railway tunnel, completed 1848, to be driven without the need for ventilation or extraction shafts. Drainage adits (above) drain the higher railway tunnels into the canal tunnel, and gantries (below) link the former. When the railway tunnels were driven much strengthening work of the canal tunnel was required in the form of heavy brick arches.

The tunnel officially closed in 1944, when maintenance ceased. Dilapidation prevented all but a couple of later exploratory journeys. A £5m restoration project in the 1990s set about reopening the canal in its entirety. Shotcrete and rock-bolting were used to stabilise some of the unlined sections of the tunnel. This reopened in May 2001, after 57 years of disuse. Boats were tugged through by electric tugs, but since 2009 have been able to transit the tunnel under their own power, with a pilot aboard, and chaperoned by a vehicle driven through the adjoined first railway tunnel (below). The journey takes about two hours.