It continued past three more halts, Langgrunn, Rørestrand and Steinsnes, before reaching (the prior) Horten Station, located at 2.2 meters (7 ft 3 in) AMSL.

The request was positively accepted by the government, who instructed the railway director to carry out surveys through Vestfold.

[4] Official planning of a railway through Vestfold to Brevik commenced with a royal resolution on 24 July 1871.

The outer followed the shore of the Oslofjord, would be 111 kilometers (69 mi) and would run through Holmestrand, Horten and Åsgårdstrand before reaching Tønsberg.

The combined and inner would be 107 and 102 kilometers (66 and 63 mi), respectively, and both involved building a branch line to Horten.

The main argument against the coastal route was that the towns already had a good steamship service, with several daily departures.

[7] A third major alternative was to bypass the coast altogether and build down the valley of Lågendalen to Larvik.

[9] Still, the county politicians preferred an interior route when it applied for the government to build the line.

[10] By 1874 the state railway commission had considered the line and had concluded that it should be built with narrow gauge.

[12] The decision, taken on 8 June 1875,[13] was made with 76 against 36 votes, and supported the compromise coastal route with an extension to Skien.

Vestre Sande and Rørestrand opened on 1 July 1929, although the latter was closed on 17 June the following year.

[21] Planning of conversion to standard gauge commenced in 1910,[22] but steady delays caused the Vestfold Line to remain the last narrow-gauge mainline railway by 1945.

[21] NSB gradually increased its focus on bus traffic on the route, reducing the number of train services to five from 1962.

[citation needed] Balthazar Lange was selected as the Vestfold and Horten Lines main architect.