Segregation and trade ports help!

[Duckinator 0]

I have been following skyestorme's let's play videos (circa 2013), and modelling my cities almost exactly. However the city did not function the same from his segregation part onwards.

Is segregation no longer possible? It says errors as buildings are not connected to the roads or something. I'm not sure if I did it wrongly or if patches has removed it.

I think one of the purposes of segregation was to avoid global market trucks to congest the roads, especially when there's trade ports or rails available. I noticed that my ports and rails aren't shipping as often as I would like, with the primary trading done by trucks. Is there a way to fix this if segregation is not possible?

Thanks!