The two-lane section of road approaching the dam is narrow, has several dangerous hairpin turns, and is subject to landslide.

There are however some narrow two-lane sections remaining.

Highway 1 has been described as a "death trap", particularly two-lane sections in northern Queensland, due to driver fatigue.

This was finished in 1982 but with the exception of the tunnels and Usk bridge which remained as dual two-lane sections.

State Route 277 carries the distinction of being the last two-lane section of US 72 in Alabama.

Those projects created bottlenecks where widened sections met winding two-lane sections, she said, and the work increased the pressure for additional widening and straightening.

Corridor A turns east on US 64, and after some two-lane sections, it becomes a four-lane highway.

A major construction project, begun in 2006, is in process to widen the remaining two-lane sections in this area to four lanes.

The motorway has three lanes both ways from shortly after junction 4 to junction 8, except for a brief two-lane section at J6 beneath the M25.

A center turn lane also exists within a two-lane section for a few blocks inside the city of Wilmington.