The young Etzel studied from 1831 to 1835 with Nikolaus Friedrich von Thouret. In 1835 Karl von Etzel worked on construction projects in France, including the Paris (Saint-Lazare)–Saint-Germain railway with the bridge over the Seine at Asnières (destroyed during the February Revolution of 1848 and later rebuilt). In 1837 he was the Chief Engineer for the construction of the Versailles Railway.