Traversing the international Bielsa Tunnel in the Pyrenees
Tunel Bielsa-Aragnouet is an international high mountain tunnel at an elevation of 1.820m (5,971ft) above the sea level, located on the border of Spain and France.
Set high in the Pyrenees mountain range, the tunnel is 3.07km (1,90 mile) long. Opened to traffic on October 1976, the tunnel passes the Pyrenean chain between Aragnouet and Bielsa and links the Hautes-Pyrénées department in southwestern France and the province of Huesca, Aragon, in northern Spain. The road is typically open all year round, with the occasional closure in winters (between 7 and 10 days per season) due to dangerous weather conditions and the risks of avalanches at its entrances.
On the Spanish side, the road to the tunnel is called A138. It’s paved. Starting from Salinas, the ascent is 21 km long. Over this distance, the elevation gain is 1.028 meters. The average percentage is 4.9 %.
On the French side, the road to the tunnel is called D173. It’s asphalted but in worse conditions. Starting from Saint Lary Soulan, the ascent is 18.93 km long. Over this distance, the elevation gain is 1.000 meters. The average percentage is 5.3 %. The maximum gradient is 11.8%.