problem had been exacerbated by the ineffective use of turnpike tolls, most of which consisted of little more than trying to fill potholes with stones. After an accident at a bridge crossing Evan Water, which killed two horses and destroyed a coach, the Post Office became fed up with trying to improve the route through the turnpike system and, considering it to be the one of the most important roads in Scotland, decided to seek alternative means to improve it. Thomas Telford stated that "the existing road is in such as ruinous state as to occasion much delay", and he managed to obtain a grant under the guise of the Commissioners of Highland Roads and Bridges, to design engineering improvements to the route. Telford was particularly concerned about being able to reduce gradients and improve drainage on roads, and recommended an improved route of a width no less than 34 feet, the central 18 feet being metalled, and the remainder being two gravel verges. The route was surveyed by William Alexander Provis in 1814–15, and commenced construction in 1816. The project was completed in 1825 at a total cost of £50,000, and like the earlier route, it was tolled. While the various turnpike trusts retained control for a few sections, the vast majority was rebuilt under the direction of Telford. Eight new toll-houses were constructed – one of these, at Dinwoodie Lodge near Johnstonebridge still exists today, and became a Grade I Listed building in December 1988. Notable engineering feats included taking the road over the Beattock Summit, construction of the original Metal Bridge just south of the Scottish Border in 1820, and carrying the road over Cartland Craigs by a 130-foot viaduct. According to author Frederick Mort, the Glasgow to Carlisle road "became a model for future engineers." 20th century In 1916, Telford's original metal bridge was replaced by a modern concrete structure at a cost of £16,000. A small section of the original bridge was housed in Tullie House Museum in Carlisle. Roads started to be classified with route numbers in 1921, with the Glasgow – Carlisle road receiving the number A74, mostly following the route as designed by Telford. On 16 May 1936, the road was diverted away from Telford's route to run from Glasgow to Motherwell via Uddingston — it is a portion of this realignment that forms the modern A74 route within Glasgow. It became