Passo di San Boldo is a mountain pass at an elevation of 710m (2,329ft) above the sea level, located in the province of Treviso, Veneto, north-eastern Italy. The road to the summit is an engineering masterpiece with 8 hairpin turns and 6 tunnels. It’s one of the famous hairpinned roads in the world.
Located within the northern reaches of the Italian Alps, the road to the summit is paved. It’s called Strada Provinciale 635 (SP 635). The 17km long route goes from Trichiana (in the Belluna Valley), at an altitude of 329m, to Tóvena (in the Val Moreno), at an altitude of 272m, through an altitude of 706m. The most challenging part of the climb is a short stretch of 700m with 5 five tunnels blasted into the rock with 8 numbered hairpin turns and six bridges. The road to the summit, just allows traffic in one direction, alternating with traffic lights. The ramp to access the south side by the neck back is a nearly vertical wall with a series of five turns through tunnels carved into the rock connected by six bridges. There is a speed limit of 30 km/h (19 mph) and a height limit of 3.2 m (10.5 ft), after buses were repeatedly stuck in the tunnels. Starting from Tovena the climb features18 hairpin turns.
This road is usually open all year, but it can be closed anytime when the access is not cleared of snow. This road replaced a steep path leading up to summit that existed since the nineteenth century but only during the First World War that project succeeded. Between February and June 1918, the Austro-Hungarian army managed to build the road in less than three months. After this fact, the road got the nickname of "road of 100 days." 1400 people, including prisoners of war and women, children and the elderly in the area, worked day and night to complete the strategic route for refueling during the Battle of Piave. Despite the topographical conditions, the slope could not exceed 12% for the passage of heavy vehicles and artillery.
It was built by 7.000 workers (mostly Russian prisoners and women) and was completed in a record time, hence it was inaugurated in June 1918 with the nickname "the road of 100 days". The works began in 1914 under the direction of engineer Giuseppe Carpenè, which employed 500 migrants repatriated between 1914 and 1916. During World War strategic reasons motivated the Austrian engineers (under the direction of Nikolaus Waldmann) to complete the work in a short time, being its construction planned for January 1918, with five additional galleries that now characterize the climb. Despite the fact that the road is located in Italy, the road is named after a Spanish hermit, called Boldo. He was a hermit living in these mountains and some years late he would become saint, San Boldo.
Pic: Solitario Motero