First come the plie drivers to lay the foundation for one fo the huge new buildings that seem to be rising on almost every street in Bangkok and other major cities. The workers follow, setting up a collection of temporary shacks on or near the site. And then, often simultaneously, the food vendors appear ready to supply a quick, cheap, above all convenient meal to anyone who happens to crave one. A thai city street without vendors is as hard to imagine as one devoid of traffic.