Sir William Arrol

From the outside, Tower Bridge appears to be built completely of brick and stone, but once inside, the skeleton of the Victorian beast reveals itself. Elaborate steelwork fills every space, held together by millions of rivets; immense cantilevered steel beams extend across the gap between the two towers forming the iconic walkways. But where did all this steel come from?

Inside the North Tower, you can see four august figures looking down from the window blinds. These are the engineers and designers who made this incredible structure a reality. One of these figures, Sir William Arrol, was the mastermind responsible for the 8km (5 miles) of iron and steel that form the Bridge's immense skeleton.

Top image: Forth Bridge in Scotland

Painting of Sir William Arrol

Who was William Arrol?

Arrol was born in Houston, Renfrewshire, Scotland on 13 February 1839. His father was a cotton spinner, so there is little surprised that young William’s first job was also in the cotton mill, aged just nine years old.

At the age of 13, the young Arrol left to begin training as a blacksmith, while also learning about mechanics and hydraulics at night school. In 1863, he joined a bridge manufacturing company in Glasgow. Using this knowledge, and his modest savings, he started his own boiler-making and general blacksmith business in 1868.

By 1872, Arrol had established the Dalmarnock Iron Works, a venture designed to take advantage of the growing opportunities in the bridge building industry. The works secured notable contracts for the Bothwell Viaduct (also known as the Craighead Viaduct) in 1875, and for the original Caledonian Railway Bridge in 1876, which crossed the River Clyde into Glasgow Central station.

Painting of Sir William Arrol c.1900. Artist unknown. Courtesy of the Institution of Civil Engineers Scotland Museum

Sir William Arrol & Co.

By the late 1870s the company had been renamed William Arrol & Co. It landed two high-profile contracts: the reconstruction of the railway bridge over the River Tay outside Dundee, which had to be rebuilt after its fatal collapse in 1879; and the now legendary Forth Bridge near Edinburgh, the first major crossing to be built entirely of steel.

Both steel bridges were at the forefront of Victorian technology, requiring construction techniques and methods of working that are still used today. Arrol also developed specialist equipment for the manufacture and erection of his steel components - this included the hydraulic riveters and cranes that were used during the construction of Tower Bridge. 

Tower Bridge's frame under construction

William Arrol and Tower Bridge

In May 1889, just a year before the Forth Bridge was completed, the contract to fabricate the iron and steel for Tower Bridge was awarded to William Arrol & Co. This included the supply and erection of 11,000 tons of steel and 1,200 tons of ornamental cast ironwork.

The steelwork on Tower Bridge was manufactured and installed with such accuracy and safety that there are no reports of any serious accidents amongst the steel workers and no reports of any materials being dropped onto shipping passing below.

Indeed, Sir John Wolfe Barry, Chief Engineer on the project declared in his diary that the final rivets connecting the two halves slotted in perfectly - an extraordinary achievement of skill and engineering – you can still see this join when you visit inside Tower Bridge.

Tower Bridge under construction © London Metropolitan Archives, City of London

William Arrol’s famous bridges, cranes and cars

In the 1890s, William Arrol & Co became a globally active company, whose famous works include the Nile Bridge in Egypt, the Hawkesbury Bridge in Australia and the Warrington Transporter Bridge across the River Mersey in England. 

William Arrol & Co were also renowned crane manufacturers. They were contracted by the Harland and Wolff Shipyard in Belfast to construct a large gantry (known as the Arrol Gantry) for the construction of three new super-liners: the RMS Olympic, the RMS Britannic and the infamous RMS Titanic.

Arrol was also involved in the early days of the motorcar business, and with George Johnson, created the first motor vehicle constructed in the UK. An Arrol-Johnson car was the first motorised vehicle on Antarctic continent as part of Sir Ernest Shackleton’s 1907-09 expedition - sadly, the car proved useless in the harsh conditions and was never used.

Tees Transporter Bridge at sunrise

The Tees Transporter Bridge

In 1911, Arrol completed his final great project: the Tees Transporter Bridge in Middlesborough. Its design encapsulated both his crane and bridge building expertise, in essence, comprising two large cranes that meet in the middle, with a moving carriageway suspended at road level to take vehicles across the river.

Interestingly, one of the original suggestions submitted for Tower Bridge was one such transporter bridg. You can see many of alternate designs when you visit inside the attraction.

Image: Tees Transporter Bridge

Steelwork in the roof of the South Tower

Arrol’s legacy

Arrol received a knighthood in 1890 and served as member of parliament for his home constituency of South Ayrshire. He lived out his later years at his home, Seafield House near Ayr, where he died on 20 February 1913. 

In 2015, he was commemorated on a Clydesdale Bank £5 note, but possibly the greatest testament to William Arrol is the fact that more than a century later his three greatest structures are still doing exactly what they were originally designed to do.

Trains still cross the Forth Bridge; cars and passengers still cross the Tees via the Transporter Bridge and Tower Bridge still stands as the gateway to London, a world-famous symbol of our capital city and country.