Telford, Thomas

Telford, Thomas (1757-1834), British civil engineer, who pioneered techniques in the construction of canals, roads, and bridges. Born in Westerkirk, Scotland, he was apprenticed to a stonemason, a trade which he practised in Edinburgh before moving to London in 1782. He taught himself the principles of architecture, and supervised construction of various public building projects before being appointed Surveyor of Public Works for Shropshire in 1786, in which capacity he built three bridges over the Severn, including one of cast iron at Buildwas. In 1793 he was appointed engineer of the Ellesmere Canal, a project for which he built 19 locks, ascending a total of 40 m (132 ft), and two major aqueducts, taking the canal over the rivers Ceriog and Dee. The Dee crossing, at Pontcysyllte, ran for 307 m (1,007 ft) over 19 arches 37 m (121 ft) high; the entire canal trough in the aqueduct was lined with iron.

This project established Telford's reputation, and in 1802 he was commissioned by the government to make a survey of the transport infrastructure requirements of Scotland. This led in 1803 to the Caledonian Canal (not finally finished until 1847), which connected the North Sea with the Irish Sea through the Great Glen. The several major lochs in the glen (including Loch Ness) meant that the canal required artificial waterways for only 37 km (23 mi) of its 96-km (60-mi) length.

Another outcome of the Scottish survey was the building of about 1,480 km (920 mi) of new roads, involving the construction of 1,200 bridges. Telford, benefiting from the work of the French civil engineer Pierre Trésaguet, devised a system of building roads of unprecedented smoothness and durability, a system that became the standard for the rest of the century: a foundation of large, dressed stones, laid by hand, was covered with a layer of smaller, tightly packed broken stones, topped by a layer of gravel; the whole was slightly raised towards the centre to ensure drainage. Telford's greatest road project was the route from London through Shrewsbury to Holyhead. To take the road over the Menai Strait to Anglesey, Telford designed the world's first major suspension bridge (1819-1826), with a main span of 176 m (580 ft) in which the deck is suspended by 16 wrought-iron chains weighing over 2,000 tonnes.

Telford was involved in many other construction projects, including several canals built to meet competition from railways, and the Göta canal in Sweden, for which he received a Swedish knighthood. He was the first president of the Institution of Civil Engineers from 1818.