The underground train system opened in July 2004. Initially, the passenger count was good but, due to it being more expensive than the sky train, the number of riders using it every day has fallen considerably. Estimates when it opened said over 400,000 people would use it daily. Lately, it’s had more like 175,000 passengers every day. Not only is it more expensive than the sky train but it also goes to some of the same places the sky train goes to. As this is the case, Thais prefer to use the sky train because at least, when you’re traveling, there’s something to see out of the window.