singlelane

Singlelane, in road engineering terms, refers to a road or bridge designed to carry traffic in both directions using a single travel lane without a dedicated lane per direction. This configuration is common on rural and mountainous routes where space constraints or construction costs make adding a second lane impractical. A single-lane section may be accompanied by passing places, pullouts, or designated turnouts to allow faster vehicles to overtake or slower traffic to let others pass.

Design and operation: Typical lane widths range from about 2.5 to 3.5 meters, depending on jurisdiction. Where there is no continuous center line or where traffic must share the lane, drivers rely on sight distance and yielding behavior to avoid conflicts. Overtaking is often prohibited or limited to passing places; signs may indicate no overtaking or yield to oncoming traffic. In mountainous or remote areas, a convoy system or temporary traffic controls may be used during daylight hours or periods of low traffic.

Safety and maintenance: The primary safety concern is the risk of head-on collisions, particularly on curves or grades with limited sight distance. Adequate pavement maintenance, drainage, and vegetation control are essential to maintain visibility. Some regions differentiate between single-lane roads and one-lane bridges, where the bridge itself constrains traffic flow and may require special signaling or control.

Variants and related terms: The UK uses the term single-track road with passing places; other jurisdictions may call them one-lane roads or narrow roads. See also: passing place, one-lane bridge, narrow road.