A few years ago, getting around Bangkok, even for the shortest of journeys, took ages. Bangkok traffic was world renowned as being the worst a city had to deal with. Luckily, this situation has changed and getting around Bangkok is much easier and considerably faster.
So,what has changed ? Well, the first additions to ease the time it took to get about Bangkok, were the expressways. These are higher standard roads with toll booths at the beginning. The charges for the expressway depends on the route you are taking but will generally cost about 45 Baht. Then came the Bangkok Skytrain ( BTS ) which focused on getting people around the central shopping and business districts of Bangkok. This works very well, with trains running regularly, but they don't add enough carriages and so the train can get very busy during rush hour, but you can read more about the Bangkok Skytrain here
Back before all the changes, you had to bargain for each taxi ride and the taxis were often so run down that you sat praying that it would last the distance.
Thankfully, Bangkok has changed. The traffic is still terrible and Thais still insist on driving their cars no matter how bad the traffic gets, but at least there are now alternatives to just sitting in the traffic getting frustrated.
Roughly 7 years ago, the much awaited skytrain was finished and all of a sudden it was possible to get from one end of town to the other in a matter of minutes rather than hours.
The route the skytrain takes is good enough for visiting all the main shopping centres and even Chatuchak market, but it is nowhere near comprehensive enough to make a serious dent in the traffic jams.
Again, roughly 18 months ago, the new subway / underground system was opened. This is our favourite means of travel as it is cool and not so crowded.
Unfortunately, the underground pretty much follows the route of the sytrain with a smattering of different stations thrown in for good measure. It is still years away from being able to cover any decent area that will allow people to leave their cars at home.