1. A dual-carriageway IS NOT any road with two lanes.
Yes, to many peoples suprise a dual-carriageway is any road with a 'central resevation', i.e. something solid seperating the traffic travelling in the different directions. The 'dual' refers to the fact there is this divide, so two seperate bits of tarmac for each flow of traffic. If it does not have a central resevation, then it is not a dual carriageway.
Oh, and if it has three lanes it is NOT always a motorway. A motorway has a 'hard shoulder', which an extra lane to the left (for emergencies) bordered by a solid white line, a dual-carriageway does not have a hard shoulder, also a motorway would have a name such as "M23" ('M' meaning motorway) and a dual carriageway would typically by a name such as "A23". Motorways also have blue signs, dual-carriageways typically have green signs.
Here are some examples:
It is also worth mentioning a 'national speed limit' dual carriageway has a speed limit of 70mph, not 60mph as many believe. A motorway also has a speed limit of 70mph (Not 80mph!) and national speed limit on a single carriageway is 60mph.
2. Why is there a hole in the roundabout sign?
Many could be thinking why is there a hole in the roundabout sign? Perhaps they ran out of paint?
Well in fact it is to help drivers, espically foreign, to understand which way to go round the roundabout. As we know the large majority of countries drive on the right, and of course the UK we drive on the left. This means most other countries go round roundabouts anti-clockwise, where in the UK we go clockwise. The gap in the sign is to show there is no road to go round anti-clockwise, you MUST go clockwise, right round the roundabout, to get to your exit.
Note: despite the gap in the sign, making it look like you can't go all the way round, you can still legally do a u-turn.
3. Why are some road names in (brackets) on road signs?
As you can see from the picture the (A264) is a brackets, however the A23 is not? Why is this?
Well the brackets bascically mean 'leads to' and the road name without brakets is the road you will be entering after the junction. So for going ahead at this roundabout will go onto the A23, which will eventually lead to the A264.
4. There is an extra line on this roundabout sign?
This indicates that for turning left there is a 'filter lane', meaning you do not need to enter the roundabout to turn left, you have a seperate and dedicated lane, and you do not need to give way to the right, just treat it like a left bend. See second picture.
5. Wow there are a lot of exits on this roundabout!
At first glance it looks like there are many exits on this roundabout, looking like Horsham is exit 6! But in fact it is exit 4?!? But why?
Well the two 'stubs' I have circled in orange are NOT exits, there are infact they are entrances coming from the M23 and A23. This is done whenever a roundabout is a bridge going over a major dual-carriageway or motorway. If you look at the second picture, which is a ariel view of the same roundabout, you can see what I mean, the bits highlighted in blue are the exits and the bits in orange are entrances from the major roads, either side of the bridge, which are detailed on the road sign.
So, without having an ariel photo how do you know which 'stubs' on the sign to count and which ones to ignore?
Well looking at the below photo you will notice the 'stubs' that are not exits are directly next to, and in line with, a true exit. We could say they have a partner or are in pairs on the sign, so if we see such a pair they we count it as one exit, not two, thus making Horsham exit 4!