Left Hand Drive Bordering Right Hand Drive
Some countries drive on the left hand side of the road (which is obviously the correct side because I happen to have been brought up in that system and I don't like change). Most however drive on the right hand side. So what happens when two countries border one another? How do the roads meet?
Before we start, let's just take a quick look at the current status of which side countries drive on. On the map below, you can see that a lot of the left drivers are ex-British Empire. The big pockets are in South East Asia and South East Africa:
A lot of the left drivers are island nations. This makes it very easy to remain that way because you don't have any borders. This explains why the vast majority of countries that were islands when the Empire lost its grip stayed that way. After all it is expensive to change all your road networks and signs.
The African countries are handily in a block and their borders with the rest of Africa tend to be in large areas with low amounts of traffic. The most common solution is to have a traffic guard or set of lights at the border to let the two streams cross each over in batches.
Thailand has borders with 4 right hand drive countries and has much higher traffic levels. However it uses a similar system of traffic lights to control the problem. But let's look at some of the more interesting crossings starting with the Island of Macau.
Macau was a Portuguese colony until it was gifted back to China. Since the infrastructure was all built for left hand drive the Chinese government opted to keep it that way. Here is the bridge which connects Macau to China:
Further along the coast there is another bridge, this time to Hong Kong:
It isn't yet a reality, but in a recent design contest to build another bridge to Hong Kong a Dutch company came up with this beauty:
One final word on one of the weirder borders. There is one place where the the UK borders France: in the Channel Tunnel. There are two main tunnels, one heading each way and they do obey left hand drive, but there is a small service tunnel lying between the two which the engineers use. This tunnel was two lanes of traffic which is left hand drive up to the half way point then right hand drive thereafter.