DO YOU KNOW WHAT A DUAL CARRIAGEWAY IS?

Many drivers appear to be unaware of what constitutes a dual carriageway or a single carriageway and the speed limits for each despite there being a definition clearly published in the Highway Code (HC) on page 45 under the heading 'Multi-lane carriageways'.

The reference in the Highway Code to dual carriageways states: 'A dual carriageway is a road which has a central reservation to separate the carriageways'.

However, it is a fact that many, many drivers may not have read or perhaps even seen a copy of the Highway Code since they took their driving test!

Part 4 of Schedule 6 of the Road Traffic Act 1984 (again, a publication which a great many people would possibly either not be aware of, or will not have had cause to read), gives the following information:

'A dual carriageway is defined as a road, part of which consists of a central reservation to separate a carriageway to be used by vehicles proceeding in one direction from a carriageway to be used by vehicles proceeding in the opposite direction.'

A huge number of drivers appear to be unaware of the definition of a carriageway. Most appear to assume that it is a lane on a road going in one direction when essentially it is the road from one kerbside (or road edge) to the other.

Therefore if there were four lanes for traffic on a road but no central reservation then that road would be classed as a single carriageway because there was no physical barrier to split the road into two.

There is a reference in the Highway Code to a single carriageway with three lanes and this is a type of road that appears to generate most confusion.

On some single carriageways, where there are three lanes for traffic, the centre lane can be used by traffic proceeding in both directions as an ‘overtaking lane’.

On others, there may be two lanes for traffic proceeding in one direction and only one for traffic travelling in the other direction. This situation is normally made clear by double white lines separating the two lanes from the one or indeed, one solid white line on the side of the road with two lanes accompanied by a dotted white line on the side with one lane. This is not a dual carriageway as there is no central reservation and this type of road is a single carriageway and is often referred to as a 'three-lane' single carriageway.

Drivers are required to be aware of the national speed limits on these roads assuming no other signs exist to post a lower speed limit. These are 70 mph for a dual carriageway and 60 mph for a single carriageway.

If a driver travels from a single (60mph) carriageway into a dual carriageway subject to the national speed limit, he/she will be greeted by a carriageway which is split into two by a central reservation and this is sometimes preceded by a sign which states that there is a dual carriageway ahead. In the absence of any such sign a driver is expected to know that the speed limit has moved up to 70mph when he/she encounters the central reservation, unless otherwise signposted.

When the dual carriageway ends, there will normally be a warning sign which indicates this and drivers are expected to recognise the fact that at the position of that sign, the speed limit has, or is about to revert to the national speed limit for a single carriageway (60) unless of course signage shows to the contrary i.e. a lower speed.

Essentially, where a single carriageway subject to the national speed limit (60) splits into two (into a dual carriageway and NOT a multi-lane single carriageway) and there are no speed limit signs, the speed limit becomes 70mph. If a two lane single carriageway (one in each direction) increases in the number of lanes available - i.e. 2 up and 1 down or 1 up and two down or even 2 up and 2 down, unless there is a permanent central reservation dividing the lanes, the speed limit remains at 60 mph as this will be a multi-lane single carriageway.