A yellow line indicates the division of a two way traffic road (it’s the center line), whether a white line indicates a lane. A solid line can’t be crossed, whereas a broken line can be crossed if it is safe to do so.
White squares indicate parking spaces. There can also be specific parking space for motorbikes.
Big yellow “X” marks on the road means no stopping on this area (usually so as not to block an intersection while waiting at a traffic light).
A red and white curbside means no parking. A yellow and white curbside means no parking, but temporary loading/unloading of goods or passengers is allowed. Curbsides can also be painted in black and white, to help distinguish them. Parking may be allowed, watch for the signs (and also watch for anyone who might be upset if you park).
Pedestrian crossing are those white stripes on the road that all vehicles ignore and that pedestrians sometimes venture on, usually ending up running for their lives.
Drivers must pay attention to arrows indicating where their lane is going, especially in Bangkok. Some lanes are for buses only.
The good thing about traffic lights in Thailand is that many of them have a counter indicating how many seconds remain before it changes colour. Of course everybody tends to rush when there are only a few seconds of green light remaining! But when it is red you know exactly how much time you have to wait, and you can relax. The not so good thing about traffic lights is that they are not always to be found at the same place. Sometimes they are just where you stop, or they can be accross the intersection, or hanging over it. You also have to pay attention to the arrows. So, mastering the traffic lights take a little practice.