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“Two-lane Road” — Here’s What It Really Means

“Two-lane Road” — Here’s What It Really Means

On the face of it, this seems like a straightforward question. 

In many ways, it is. However, there still seems to be a significant amount of discussion about what is and what isn’t, technically speaking, a two-lane road. 

What if there is a bus or carpool lane on one side that is not accessible to the cars driving in the two regular lanes?

What if there are exits that allow entry to and exit from the two main lanes? What if there is a median barrier between the lanes? 

And, by the way, what do you call those mega highways with sixteen lanes going in either direction? 

Here is a brief run-through of what a basic two-lane road is and where the exact parameters of the definition of a two-lane road lie.  


What is a two-lane road? 

A two lane-road has two lanes, with one single-vehicle-width lane going in either direction and no median barrier between the lanes. In the United Kingdom, it is usually referred to as a single carriageway. 

A single carriageway ought not to be confused with a single-track road, which has just one lane. Single-track roads have places for cars going in opposite directions to pass one another. 

Many people also refer to a “single carriageway” as an “undivided highway,” because of its lack of a median barrier between the lanes.

It is important to distinguish between lanes of traffic and carriageways, considering the confusion that seems to arise between the UK and the US on this point. 

A two-lane road has two lanes, but only one lane for each direction of traffic. 

A two-lane road usually has at least segments where passing is permitted, as indicated by a broken yellow centerline. It may well also have zones where no passing is permitted, as indicated by a solid or double solid yellow centerlines. 

The fact that a two-lane road has sidewalks or road verges, such as exit and entrance ramps, does not prevent it from being a two-lane road. 

The dimensions and designs of roads have a rich history. The term “carriageway” long predates cars. 


It was derived in the 12th century, when the Laws of Henry I, which were given out between 1114 and 1118, proscribed the minimum width for the via Regia (the King’s Road). Henry I of England mandated that roads be wide enough for two carriages to pass one another. 

In addition, he also said they had to be wide enough for 16 armed knights to be able to ride beside on another, but that is a story for another time. 

Unlike a two-lane road, a double carriageway has not one but two lanes going in either direction, which are divided by a central reservation, usually a strip of grass, often with metal barriers and vegetation. 

A multi-lane road or highway has two or more lanes for traffic going in either direction. A multi-lane road can have as many as 26 lanes, as the Katy Freeway in Houston, Texas does. 

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