Which engineer built the first successful steam locomotive?

Which engineer built the first successful steam locomotive? Richard Trevithick built it.

Trevithick, a Cornish mining engineer, pioneered compact high-pressure steam engines, which were lighter and more powerful than the low-pressure designs commonly associated with James Watt. He applied this technology to rail transport in South Wales.

On 21 February 1804, Trevithick’s unnamed locomotive hauled iron, wagons, and passengers along the tramway of the Penydarren Ironworks near Merthyr Tydfil. It carried about 10 tons of iron, five wagons, and 70 people over roughly 9.75 miles. The journey demonstrated that steam traction on rails was possible.

The locomotive was too heavy for the primitive cast-iron plateway and damaged the track, so it did not begin a lasting railway service. George Stephenson later became famous for commercially successful locomotives, especially Rocket, but he was not the first engineer to build a successful steam locomotive. Trevithick also built the road vehicle Puffing Devil in 1801 and the demonstration locomotive Catch Me Who Can in 1808.