Right- and Left-hand Traffic - Terminology

Terminology

Universally (following a treaty; see below) each country specifies a uniform road traffic flow: left-hand traffic (LHT) in which traffic keeps to the left side of the road, or right-hand traffic (RHT) in which traffic keeps to the right.

Vehicles are usually manufactured in left-hand drive (LHD) and right-hand drive (RHD) configurations, referring to the placement of the driving seat and controls within the vehicle. Typically, the placement of the steering wheel is opposite to the rule of the road: LHT countries use RHD vehicles, and RHT countries use LHD vehicles. This is so that the driver's line of sight is as long as possible down the road past leading vehicles, an important consideration for overtaking (passing) manœuvres.

There are LHT countries where most vehicles are LHD (see Caribbean islands below)—and there are some countries with RHT and mostly RHD vehicles, such as Afghanistan, Burma, and the Russian Far East, in the last case due to import of used vehicles from Japan. Many countries permit both types of vehicles on their roads. Terminological confusion can arise from the misuse of left-hand drive or right-hand drive to indicate the side of the road along which vehicles are driven.

The terms nearside and offside are related terms used in many English-speaking countries to refer to the sides of a vehicle: the nearside is closest to the kerb and the offside is closest to the centre of the road.