Tronåsen is the ancient road between Moi and Flekkefjord. It is today a protected route. The road ends at Bakke Bro (bridge), an old suspension bridge from 1844 crossing the river Sira. The Tronåsen route is part of the old Western main road, and has eight sharp turns from Tronvik to the county border, and three sharp curves down in the county of Vest-Agder. The road was said to be one of the most dangerous stretches during the Rally Monte Carlo in 1931. The road is narrow only 2,5 - 3,5 m wide and very steep. On this protected route every five years they organise a popular veteran car rally race.
The Tronåsen road is open for small cars during the summer and is oneway road from Tronvik to Sira.