Even its name, trenillo (little train), gives away that this was a narrow-gauge railway, though in this case, an especially narrow one. Our Greenway recovers part of the Valdepeñas–Puertollano railway, built to an unusually small gauge of just 75 cm —narrower even than the standard metre-gauge lines found elsewhere in Spain. Only one other line in the country, in Girona, used this gauge.  Promoted by small local investors, the first section —Valdepeñas to Calzada de Calatrava— opened in December 1893. Its first terminus gave rise to the line’s popular name: Trenillo de la Calzá —trenillo for its diminutive size compared with the imposing broad-gauge MZA services at Valdepeñas station, and de la Calzá from the local rendering of its destination, Calzada de Calatrava.  Ten years later, Calzada ceased to be the terminus. The original 42 km were extended by another 33 km (now part of today’s Greenway) allowing trains to continue on to Puertollano. Or rather, to its stations, plural, because in this mining town the broad-gauge MZA trains linking Ciudad Real and Badajoz met also their metre-gauge counterparts from Almodóvar del Campo to Fuente del Arco in Badajoz, the longest narrow-gauge railway in Spain.

From that distant year of 1903 onwards, Puertollano saw trains of three different gauges converge. The most modest of them was the Calzá one, a near toy-like train, prone to frequent derailments, which passengers themselves would often help to set back on the rails. The aim of reaching Puertollano was to transport coal from the mining basin to Valdepeñas, but MZA actively undermined this trade. The line survived only on limited local traffic, including basalt from ancient volcanoes in Campo de Calatrava scattered along its route. The promoters planned to extend the line from Valdepeñas to Villanueva de los Infantes, but dire finances prevented it. In 1932, the State took over the line through the EFE railway company.  After the Spanish Civil War, EFE considered converting the track to metre gauge and connecting it to the Fuente del Arco line, but the plan was never realised. The railway continued to deteriorate, until in 1963 the government closed it permanently and dismantled all its facilities.