Do boats use right- or left-hand traffic on the NIDA line (Khlong Saen Saep Express Boat)?

Local custom may have been established, but normally the skipper signals his intend to pass port or starboard  or to overtake by ether side.  

but as a general rule that signal would most likely follow this:

Unless otherwise agreed, when two power-driven vessels are meeting on reciprocal or nearly reciprocal courses so as to involve risk of collision, each shall alter her course to starboard so that each shall pass on the port side of the other.

and there are vast numbers of other rules

Port four letter word same as your left

Thanks for the info, but I'm not interested in how vessels pass each other. I'm interested in going to the pier on the correct side of the river. For example if I travel to east, should I go on the pier at the southern or nortner side?

Thanks for the info, but I'm not interested in how vessels pass each other. I'm interested in going to the pier on the correct side of the river. For example if I travel to east, should I go on the pier at the southern or nortner side?

I see,  you mean which bank of the river are they loading from for up stream or down stream routes.   Sorry,  I don't know that one. 

Thanks for the info, but I'm not interested in how vessels pass each other. I'm interested in going to the pier on the correct side of the river. For example if I travel to east, should I go on the pier at the southern or nortner side?

Apart from Pratunam which has two piers, north and south, every other stop has only one.

The boats will arrive from both the rh and lh side and go in the opposite direction.

For example if I was stood at Asoke pier the boat coming from my right would be heading out of town towards Wat Sribunruang via Khlong Tan and The Mall Bang Kapi.

However the boat coming from my left would be heading into town to Pratunam via Nana and Chitlom.

Basically you need to know if you are going west or east and get the boat coming from the opposite direction.

Thanks for the info, but I'm not interested in how vessels pass each other. I'm interested in going to the pier on the correct side of the river. For example if I travel to east, should I go on the pier at the southern or nortner side?

Apart from Pratunam which has two piers, north and south, every other stop has only one.

The boats will arrive from both the rh and lh side and go in the opposite direction.

For example if I was stood at Asoke pier the boat coming from my right would be heading out of town towards Wat Sribunruang via Khlong Tan and The Mall Bang Kapi.

However the boat coming from my left would be heading into town to Pratunam via Nana and Chitlom.

Basically you need to know if you are going west or east and get the boat coming from the opposite direction.

This simplifies things. Thanks!