Heatwave

August in Europe. The height of summer. A time when people all across the continent down tools and migrate to the beach. Commerce and industry temporarily halt, as folks prioritise enjoying life over all else.

Little happens during August. On those rare occasions when something does, it receives scant coverage or comment. Writers and their readership are all relaxing. Reconnecting with family and friends. Or rediscovering simple pleasures, free from time pressures.

Something interesting did happen this August. The river Thames, the waterway that runs through the very heart of London, was closed to river traffic. Indefinitely.

The cause was not an accident. Natural disaster. Nor terrorism event.

It was climate change. Greed. Incompetence. Short-termism.

A story 250 years in the making, that all started with a humble rowboat.

“Row row row your boat“

Way back in 1750, Frederick was a waterman. A humble profession that involved ferrying passengers across the river Thames. It was physically demanding work. Battling strong tides. Rain or shine. Summer or winter.

Competition amongst watermen was fierce in the big city of London. With a population then in the region of 750,000, the nation’s capital was crowded. Noisy. Polluted. Smelly.

Frederick preferred a quieter life. He operated a ferry outside of a village several miles west of London. It departed from a set of stone steps that still exist today. Ensuring that his lady passengers did not get their skirts wet when embarking or disembarking his boat.

Frederick serviced the steady flow of passengers travelling between Middlesex on the river’s northern bank to Surrey in the south. After having worked hard and saved harder for many years, Frederick opened a tavern beside those river steps. His passengers could escape the elements, and enjoy a refreshing drink or hot meal while they waited for the ferry.

Life was good! Frederick’s fortune grew as his business interests prospered.

Then, as it so inevitably does, life happened.

A decade after opening the tavern, a toll bridge was constructed across the river just a mile further west. At a penny per person (£2.23 in today’s money), it was cheaper, faster, and safer than Frederick’s little ferry.

Business limped onwards, a mere shadow of its former glory days. Then a decade later, James Watt patented the steam engine. Commercialising a lineage of ideas stretching back at least 1600 years to Hero of Alexandra’s “aeolipile“, and sparking the industrial revolution.

Steam power led to a boom in manufacturing in the major cities and towns across the land. Goods that needed transporting to be sold in the capital or beyond.

The Grand Junction Canal was established to transport goods via a network of inland waterways from the Midlands to the Thames. Once complete, this more direct route shaved roughly 100 miles off the traditional overland journey, terminating near the new toll bridge.

Frederick’s family watched helplessly as fully laden barges and ships sailed past. Suddenly their once-prosperous tavern was located in entirely the wrong place!

A bridge too far

By the 1820s, London’s population had nearly doubled to around 1,400,000 people. The city sprawled ever westwards, consuming all the fields and villages that lay in its path. Local residents resented the inconvenience of having to detour several miles each way to use Frederick’s ferry or the toll bridge.

They learned that it had cost the equivalent of £2,500,000 in today’s money to construct, and set about lobbying the government to establish a new bridge closer to home.

Eventually, an act of parliament was passed to establish a company to construct and operate the new toll bridge. Property developers lobbied hard to ensure that the compulsorily land acquisition powers awarded to the company for the bridge were extended to include a nearby estate that was subsequently sold on for a handsome profit.

From the outset, the project was compromised.

The chief engineer was tasked with building “a bridge of suspension with a view to the strictest economy”. The suspension style was selected because it would retain a wide navigable waterway beneath the suspended spans.

There was only one problem. Nobody had ever constructed such a large suspension bridge before.

Two large stone piers were sunk into the river bed to support the bridge. Less than three years after construction had begun, the new toll bridge was opened to the public was opened with much fanfare.

It quickly became apparent that the desire for the “strictest economy” had yielded an outcome unfit for purpose. At high tide, there was only 11 feet (3.5 metres) clearance between the water and the suspended timber decking of the bridge, preventing all but the shortest of barges and ships from safely navigating beneath.

Large stone arches had been constructed on each pier to support the suspension towers. At their widest, each archway was only 14 feet (4.25 metres) across. According to the Design Manual for Roads and Bridges, that was only slightly wider than the narrowest permissible single traffic lane on a modern road!

While the bridge had footpaths running down either side between the suspension towers, it left pedestrians with no choice but to run the gauntlet amongst the horses and carriages to pass through the arches.

The total cost of acquiring the land and building the original bridge was the equivalent of nearly £9,000,000 in today’s money.

If at first you don’t succeed…

By 1870, the toll bridge was poorly maintained and structurally unsound. Its wooden decking was rotten, and in some places had holes large enough for a policeman to fall through. Yet with London’s population having swollen to more than 4,500,000 people it was used more than ever.

The bridge made headlines on the day of the annual University boat race, when it bowed and swayed alarmingly as nearly 12,000 spectators crowded onto it to watch Cambridge beat Oxford to the title.

Unsurprisingly, the prospect of 12,000 deaths proved insufficient to motivate the owners to address decades of neglect and accrued technical debt rather than just continue collecting tolls. Shortly afterwards an act of parliament nationalised several of London’s bridges over the Thames, and ceased charging tolls.

The new owners were greatly concerned with the bridge’s structural integrity. They commissioned an investigation that recommended the bridge be pulled down and replaced.

Once again “economy” was the order of the day. The stone piers in the riverbed were reused. This meant the maximum width of the new bridge remained the same as that of the old, and its ability to support heavy loads was similarly compromised.

The chief designer sought to widen the road between the new suspension towers by replacing the original stone arches with cast iron towers that were both much lighter and narrower. More than half a century after it originally opened, the bridge could now support two lanes of traffic!

Wood was again chosen as the material of choice for the decking of the bridge.

The replacement bridge cost nearly £10,000,000 in today’s money.

After a precious few good years, life happened once again. The automobile arrived in the United Kingdom. Trucks, buses, and cars weighing more than the bridge designer’s engineering tolerances had anticipated quickly became commonplace. Traffic volumes and congestion beyond imagining soon plagued the capital.

The new bridge was pretty but plagued by maintenance issues.

Those who worship old things had the bridge heritage-listed shortly before its hundredth birthday. That listing was subsequently upgraded, effectively putting an end to any hope of the bridge’s inherent design issues ever being remedied.

Not everyone likes it quite as much as the heritage listers however.

Terrorists have attempted to blow it up on three separate occasions, succeeding in having the bridge closed to traffic for a year or more at a time.

Unfunded emergency maintenance issues have achieved a similar outcome several times throughout the bridge’s lifespan. Many of the cast iron parts used in the original suspension mechanism were replaced with steel to cope with the increased load.

Penny pinching local councils long ago replaced the wooden deck with asphalt coated plywood to save money. Creating a cottage industry of lowest cost bid outsourced maintenance crews to regularly close the bridge so that they can replace the swiftly rotten plywood panels.

Heatwave

Last year, maintenance crews observed cracking in the support structures of the bridge. Once again, the bridge was closed to traffic, disrupting the daily commute for many of London’s 9,000,000 residents, while local councils and Transport For London argued about who should pay for the unfunded repairs.

Eighteen months later the bridge remains closed, and the arguments continue.

The estimated repair bill? £140,000,000.

Then August arrived.

The height of summer.

London experienced something of a heatwave.

Six consecutive days where the temperature exceeded 34 degrees Celcius.

Something else that was beyond the bridge chief designer’s wildest imaginings, more than a century ago when he was calculating the engineering tolerances that his magnificent creation would need to be able to cope with. Inadvertently creating a lasting legacy that will likely trouble many generations of commuters to come.

200 years ago some short-sighted stakeholders with deep pockets and short arms instructed the original bridge designer to seek savings and economy. Maximise their return on investment.

One of the many resulting compromises was the width of the stone piers that supported the bridge.

140 years ago a different set of short-sighted stakeholders, with deeper pockets and a similar zeal for savings, decided the replacement bridge should be built upon those same stone piers.

To accommodate the desired second lane of traffic on a bridge the same width as the original, imagination and compromise was required. Bulky strong stone support towers were traded for narrower cast iron support towers. A compromise. Less bulky. Less strong. Less reliable.

However, cast iron is fragile.

It shatters easily.

There is a good reason why only two cast iron suspension bridges remain in the world today.

“Unseasonably” hot weather, the new normal, caused the cracks in the cast iron suspension towers to significantly worsen. Engineers working for the local council raised the alarm that the bridge could fail at any time.

Fearing public injury, and the legal liability that tends to follow, the local councils ordered the bridge fully closed. No more pedestrians or cyclists passing over it. No more river traffic passing beneath it.

London’s main arterial waterway, the Thames, is closed. Indefinitely.

Not that anyone has noticed. It is August after all.

Which is troubling. More troubling is the uncomfortable question about how many other old man-made structures are going to be similarly vulnerable to climates outside the tolerances envisaged by their designers?

Cracking dams. Flooding. Insect infestations. Melting asphalt. Oxidation. Subsidence.

The problems will be many and varied, yet the underlying cause is something we are all aware of but try our level best not to think about.

Next year’s University boat race will need to find an alternative route for the first time in 175 years. Perhaps the organisers could look a little further West? Near a nice 250-year-old pub located beside some ancient river stairs. It was once owned by a guy named Frederick, who did a bit of rowing himself.

References

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• Bank of England (2020), ‘Inflation Calculator‘
• BBC (2014), ‘James Watt’, BBC History
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• Edith’s Streets (2016), ‘Riverside north of the river and west of the Tower. Hammersmith Riverside‘
• Historic England (2020), ‘Hammersmith Bridge‘
• Hitchcock, T. (2020), ‘London 1780-1900’, Digital Panopticon
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• Rocque, J. (1746), ‘An Exact Survey of the citys of London Westminster ye Borough of Southwark and the Country near ten miles round / begun in 1741 & ended in 1745 by John Rocque Land Surveyor ; & Engrav’d by Richard Parr‘
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• The Guardian (2000), ‘Bomb explodes on Hammersmith bridge‘
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• Transport for London (2020), ‘Hammersmith Bridge – full closure‘
• Trust for London (2020), ‘London’s population over time (1931-2030)‘
• William Hogarth Trust (2018), ‘In Georgian Footsteps‘
• Wood, V. (2020), ‘Heatwave: Hammersmith Bridge fully closed following safety concerns’, The Independent