*** D is for Dual Carriageway ***
A dual carriageway is a road which has a central reservation to separate the carriageways.
They are usually used to link major roads or areas together, and where there is high traffic flow – where two lanes would benefit the traffic to keep it moving.
Despite the name, some ‘dual carriageways’ have only one lane in each direction, or maybe three lanes: it is the separation between opposite directions that makes it a dual carriageway not the number of lanes.
How do you join a dual carriageway?
If there is no slip road, emerge as you would like a left turn at a junction. Ensure that you emerge into the left hand lane of the dual carriageway, and you wait for a big enough gap to build up your speed.
If there is a slip road, indicate your intention to join, and use the slip road to adjust your speed to that of the traffic on the dual carriageway. Look for a gap in the traffic, and then merge into the left hand lane. Consider a quick sideways glance (blindspot) to check that there are no vehicles next to you, but also use your mirrors effectively to see the position of the vehicles on the main dual carriageway.
Once you have joined, remember to cancel your indicators, and continue to build up your speed to match the speed of other vehicles.
If other vehicles are trying to join the dual carriageway whilst you are already on it, follow these tips:
Don’t try to race them whilst they’re on the slip road.
Look well ahead, if there are several vehicles trying to join, be prepared to adjust your speed,
Show consideration for traffic joining, and if it’s safe to do so, change lanes to give the joining traffic space,
Take extra care if the dual carriageway curves, as vehicles on the slip road may have difficulty seeing vehicles on the dual carriageway.
How do you leave a dual carriageway?
Know which exit you want to take by looking at road signs or listening to your sat nav. Position yourself in the left hand lane in good time. Make sure you plan well ahead, and aren’t stuck in a far right hand lane when you should be coming off the dual carriageway. Look for the countdown markers that tell you how far it is to the exit – 300, 200, 100 yard markers.
Try to avoid slowing down on the dual carriageway before you exit, as you could hold up vehicles behind you. Try to wait until you are on the exiting slip road before braking. If the slip road is really short, you may need to start braking just before you exit to bring your speed down.
If you miss your exit, carry on to the next one.
Remember that you will be used to driving at high speeds whilst on a dual carriageway.
When you exit a dual carriageway, your judgement may be affected. Going 40mph may feel like 20mph. Glance at your speedometer to check your actual speed.
*Reproduced with the kind permission of Mercury Driving School