"Blue Arrow" BCFe 4/6 # 736 of the BLS foundation at Chambrelien, a switchback station, meeting BLS push pull train in "Kambly" paint scheme, with leading cab car Bt # 990. Thie iconic vehicle "Blue Arrow" from 1938 ran a birthday party train on this wonderful summer day, from Olten via Solothurn-Biel-Sonceboz-La Chaux-de-Fonds-Le Locle-La Chaux-de-Fonds-Chambrelien-Neuchatel-Biel-Solothurn-Olten.