When people say that a road has "two lanes"?
- Two lanes total, one travelling in one direction, and one travelling in the opposite direction?
- Two lanes travelling in one direction, and two more lanes travelling in the opposite direction?
When people say that a road has "two lanes"?
Two-lane expressway (same concept as road) :
- A two-lane expressway or two-lane freeway is an expressway or freeway with only one lane in each direction, and usually no median barrier.
Two-lane road:
Wikipedia
Your second picture represents a:
- (of roads and highways) having two or more lanes for traffic
According to the World Road Association-PIARC, an international standards body, a two-lane road is simply a
Road designed to permit two lanes of traffic to be accommodated side by side.
A search on the term shows that this usage is used by governments and construction companies in the United States, Canada, New Zealand, and Scotland. We may presume that at least in industry circles, the understanding of a two-lane road would be something like what the Manual on Uniform Traffic Control Devices, which sets US national standards for road signs and markings, offers in this diagram:
Roads with more than two lanes, regardless of direction of traffic, are referred to generically as multi-lane roadways.
However, lanes should not be confused with carriageways or with directions of travel. Consider, for instance, this Wikimedia image of highway 401 in Ontario:
There are sixteen to seventeen lanes of traffic, but these are divided up into six carriageways, three in each direction. So the confusion that a four-lane road refers to a road with four lanes in one direction may arise because it is hard to imagine such a large road on a single carriageway; almost certainly it would be at least a dual carriageway, with four lanes of traffic in each direction, but properly an eight-lane roadway.
A two lane road means one lane in each direction. Otherwise, there would be no need for special instructions, like this one, teaching drivers how to safely pass on a two lane road.
A two-lane road is the simplest road possible - no central dividing of the traffic, other than for a dotted line - just one 'lane' in each direction. But in Britain it is usually called a single-carriageway road.
In Britain this is a single-carriageway road:
It is also what I would call a two-lane road.
This is a two-lane dual carriageway
This is a four-lane motorway
with a northbound and a southbound carriageway.
The word carriageway (sometimes written as two separate words) long predates the internal combustion engine. It is defined as 'that part of a road which is open to vehicular traffic', in the early days this would have been horse-drawn. (OED).