Sir William Arrol & Co. was a Scottish civil engineering and construction business founded by William Arrol and based in Glasgow. It built some of the most famous bridges in the United Kingdom including the second Tay Bridge, the Forth Bridge and Tower Bridge in London.

The Company was founded by William Arrol, born in Houston, Renfrewshire in 1839, the fourth child of Thomas Arrol, a cotton spinner. He started work at the age of nine in a cotton mill, having passed himself off as thirteen. In 1850, the family moved to Paisley and William found work at Coats’s Cotton Thread Manufacturing making bobbins. At the age of fourteen he was apprenticed to a blacksmith at Paisley, supplementing his practical education with night school classes and the purchase of books on engineering.^[1]

At end of his apprenticeship William Arrol worked as a journeyman blacksmith with mixed success. Work was not easy to find and in 1858, now aged nineteen, he took a job at Ker’s factory at Paisley. Eventually he was engaged as a foreman at Laidlaw’s Engineering Works in Glasgow. Here he was entrusted with his first bridges: the Greenock and Ayrshire Railway at Greenock in 1865 and the West Pier at Brighton 1866. After two years, Arrol had saved enough money to set up with a friend as boiler and girder makers. However, they incurred heavy losses through non-payment by customers and the partnership was dissolved. On his own again with his small works in Glasgow, in 1871 he was given the construction of railway bridges on the Balerno line in Edinburgh.^[1]

In 1872, now in his early thirties, Arrol left his old works and moved to Dalmarnock in south Glasgow. His first important contract was for a bridge over the Clyde at Bothwell for the North British Railway. This bridge, which was 120 feet above the water, was notable for Arrol’s introduction of the idea of building the girders on land and rolling them out pier to pier. In 1875 he built the first of the two great bridges for the Caledonian Railway over the Clyde. Faced by a strike by the riveters he invented a hydraulic riveting machine, later to enjoy widespread use in the shipbuilding industry.^[1]

December 1879 saw the great Tay Bridge disaster where the railway bridge collapsed under the lateral pressure of high winds, barely a year after it had opened. William Arrol was awarded the contract for the new bridge. Construction of the new Tay Bridge was started in 1882 and it opened in 1887. Almost simultaneously, William Arrol was also working on the Forth Bridge. Construction began in 1882 and when it was opened in 1890 it had the longest single cantilever bridge span in the world. William Arrol’s commitment to these two bridges was rewarded with a knighthood: Sir William Arrol & Company Ltd was incorporated in June 1893.^[2] The completion of the two Scottish bridges gave Sir William Arrol an international reputation and in the succeeding years bridges were built around Great Britain, Europe and as far as Australia. Perhaps the best known was London’s Tower Bridge opened in 1894, where Sir William Arrol erected all the steel work.^[1]

The development of Dalmarnock Works to cope with Arrol’s increased business involved the construction of new buildings with large spans and roofs of steel and glass which let in light throughout the building. Their size allowed the installation of large overhead cranes with up to 100 tons lifting capacity. This became an activity in its own right as similar buildings were constructed for other companies.^[3] Also arising out of Dalmarnock Works and bridgebuilding were cranes. particularly for shipbuilding; they had a loading capacity ranging from five to 150 tons. The most famous crane. the largest of its time, is the Titan Crane completed in 1907; a gigantic cantilever crane of 150-ton capacity. for John Brown & Company.^[1] With this increased range of activity, the Dalmarnock Works occupied 17 acres and employed 2000 men plus thousands more working on outside contracts. Sir William died in 1913 but the Company continued as an independent entity until 1969.^[4]

The company was acquired by Clarke Chapman in 1969 and the Dalmarnock Works were closed in 1986.^[9]