Quang Tri province to Savannakhet in Laos, and from Saigon to Phnom Penh in Cambodia. None of these other lines were ever implemented in their entirety, although the Hanoi–Dong Dang line later allowed for rail connections to Guangxi, and the first of the Tan Ap—Thakhek line into Laos were built before construction was abandoned. Doumer's plans were adapted, however, to provide a railway link connecting Da Lat and Tháp Chàm in Ninh Thuận Province, at a cost of 200 million francs. Construction Swiss engineers, who had experience at building zigzag railways for use on steep slopes, were hired to complete the line. Initial surveys took place in 1898, and construction began on the Tháp Chàm–Sông Pha section in 1908. By 1913, tracks had reached the town of Tân Mỹ, and the first trains began to use this portion of the line. The rest of the Tháp Chàm–Sông Pha section opened in 1919, completing the first phase of construction. The second phase took comparatively more time to complete, due to the mountainous terrain inland from Sông Pha (Krongpha). Although the following section, from Sông Pha to Eo Gio (Bellevue), was only long on a map, its steep grade (120‰) required the use of a rack and pinion system. The Sông Pha–Eo Gio section was completed in 1928. The next section, from Eo Gio to Đơn Dương (Dran), was relatively flat, and was completed in 1929. From Đơn Dương to Tram Hanh (Arbre Broyé), another length of rack rails was laid, this time with a grade of 115‰ and with a more meandering route than previously; this section was completed in 1930. The remaining distance from Tram Hanh to Da Lat was said to be the most difficult, as it crossed the Lam Vien Plateau, above sea level. The terrain was again relatively flat from Tram Hanh to Da Tho (Le Bosquet), but required the construction of three railway tunnels; finally, the Da Tho–Trai Mat section, which was the final rack rail section with a grade of 60‰, was laid down; the railway tracks finally reached Da Lat in 1932. The section linking Sông Pha to Da Lat was only long, but rose almost along a winding route with three rack rail sections and five tunnels. Da Lat Railway Station, one of the first colonial-style buildings to be built in the area, was completed in 1938. Abandonment Throughout the Vietnam War, the