Pavel Petrovich Melnikov (Russian: Павел Петрович Мельников, 3 August, 1804 - 3 August, 1880 in Lyuban) was a Russian engineer and administrator who, in his capacity of Minister of Transport Communications, was in a large measure responsible for the introduction of railroad construction in Imperial Russia.
In 1825 Melnikov graduated from the Engineering Institute of the School for Communication Routes, taught here (professor of applied mechanics since 1833). In 1833 he joined the St. Petersburg Artillery School. In the Summer of 1839 Melnikov and another colonel, Nikolai Osipovich Kraft (1798-1857), were sent to the United States to inspect its railroad system and recommend technology to be used in Russia. The travellers returned in the Fall of 1840. Based on his experience Melnikov suggested to adopt 5ft wide gauge for the planned Moscow-Saint Petersburg Railway (before, only short line connecting St. Petersburg and Tsarskoe Selo has been built in 1836-37 under František Josef Gerstner). The gauge was approved as the new standard on 12 September 1842.
When construction of the Moscow-Saint Petersburg Railway started in 1842 Melnikov was named the construction manager of its northern part. Since 1862 he was the chief manager of the railway, during 1866-69 he served as the Minister of Transport Communications, during 1870-75 as a member of the Committee of Railroads.
Melnikov also worked in area of water-based transportation systems and other engineering projects. He is author of first books about railroad construction in Russian language.