Addresses in Bangkok use the Thai addressing system, which may be a little confusing
to the uninitiated. Large roads such as Silom or Sukhumvit are Thanon often abbreviated
Th or glossed Road / Avenue, while the side streets branching off from them are called
Soi. Soi’s are numbered, with even numbers on one side and odd ones on the other.
Thus, an address like 25 Soi Sukhumvit 3 means house/building number 25 on the 3rd
Soi of Sukhumvit Road. While the Soi numbers on each side will always advance upward,
the numbers often do not advance evenly between sides - for example, Soi 55 could
be across from Soi 36. Many well-known Soi's have an additional name, which can be
used instead of the number. Soi 4 is also known as Soi Nana, so the address above
might thus also be expressed as 25 Soi Nana. The extension / x is used for new streets
created between existing streets, as seen in Sukhumvit's Soi pattern 7, 7/1, 7/2,
9, 11. Note that some short alleys are called trok instead of Soi.
To make things a little more complex, some large Soi’s like Soi Ekkamai
( Sukhumvit Soi 63 ) and Soi Ari ( Phahonyothin Soi 7) have their own Soi’s.
In these cases an address like Soi Ari 3 means the 3rd Soi off Soi Ari, and
you may even spot addresses like 68/2 Soi Ekkamai 4, Sukhumvit 63 Road,
meaning 2nd house beside house 68, 4th Soi off Ekkamai, the 63 rd Soi of
Sukhumvit. In many sois the house numbers are not simply increasing, but
may spread around.
To further confuse the tourist who doesn't read Thai, the renderings of Thai street
names in the Latin alphabet is not consistent. The road running towards the (former)
airport from the Victory Monument may be spelled Phahon Yothin or Pahon Yothin or
Phahonyothin or Phaholyothin depending on which street sign or map you consult. It's
all the same in Thai, of course, only the romanisation varies.
And if that is not confusing enough, most of the larger streets tend to change names
altogether every few kilometres. Sukhumvit is called Sukhumvit on one side of the
toll way (roughly east), but it becomes Ploenchit just before you cross Thanon Witthayu
(aka Wireless) going towards the river. Keep going just a few more streets and it
becomes Thanon Phra Ram Neung ( or Rama I ) after you pass Thanon Ratchadamri. But
if you were to turn right onto Ratchadamri, in just a few blocks you will find yourself
on Thanon Ratchaprarop ( past Phetchaburi, aka New Phetburi, which is called Phitsanulok
closer to the river ). Got it?
Fortunately, there is logic to these name changes: most of them are neighbourhoods.
It would not make sense to call the road Sukhumvit if it's no longer running through
the Sukhumvit area, would it? Thus, Sukhumvit becomes Ploenchit where it runs though
the Ploenchit area. It's when you are able to grasp the city in terms of its neighbourhoods
that it both becomes more navigable and more charming. Likewise, Pratunam and Chatuchak
are much more than just markets; they are boroughs, each with its own distinct character.