Trees In Singapore, Umbrella Signs and Motor Cycle Shelters

I love the trees in Singapore. They arch across the road providing shade and shelter.
I had heard of rain trees but was puzzled by the umbrella roadsigns on the motorway driving through the city. A motorcyclist explained: The signs are telling motorcyclist that they can shelter under a bridge a certain number of yards ahead. So slow down ready to take shelter. Surely you can shelter under any bridge? No. You would be either blocking traffic or in danger of being hit. The motorcyclists refuge are to one side under the bridge and separated safely from the slow lane of traffic on the left by barriers.

Why don't they have that in other countries? Because the rain is not so torrential and the bridges aren't necessarily new and big enough for the shelters to be built. What's more Singapore has a huge number of bridges throughout the city near enough to each other for there to be a nearby bridge for the motorcyclists to take cover.