I am writing a personal blog, and there, I want to describe the bus system of the city that I live in now. Bus system does not work on the schedule. They usually arrive sooner to later than the announced time.
Is "an unorganized transporatation system" a proper way to describe it?
I feel it does not communicate the meaning well.
"Unorganised" would imply that it is not at all organised, which is probably not true - transport networks have a great deal of structure and organisation. You appear to be making a comment on the quality of its organisation rather than a complete absence of it.
What I think you mean to say is that it is 'disorganised', meaning "badly planned and without order". You could also say it is 'badly organised', 'poorly run', or perhaps 'mismanaged'.
An alternative is unpunctual. Lexico defines this as "not happening or doing something at the agreed or proper time." It's the opposite of punctual.
Lexico's examples show the word can be use of people and of transport systems. One of its examples is:
The trains into Tbilisi were notoriously unpunctual.
Were the buses always late then you could have used something like "delay-prone". However, given that the buses appear to arrive early as often as they do late, that's no good.
The problem is, you may be asking too much of any single adjective to explain that early-or-late aspect. Instead, perhaps you could use the generic, "unpredictable" and then expand a little to make it clear that the unpredictability is in terms of time versus schedule (as opposed to the buses arriving perfectly on time but at entirely wrong destinations, or frequently being hijacked by giant squirrels).
