I have a pretty good size (about 1/8 of a large map) city going. It is a on a street grid of 12 X 22. I have a few sections of street showing "heavy" use in spite of having bus stations. Under those streets I have subways showing "congested".

Has anyone ran into this and will building double subway lines side by side solve it?

Added a parallel line and with in months it was also showing as "congested".

Adding bus stops on the surface makes no difference to the subway but it did bring the surface roads down from heavy to moderate.

The really odd thing is that the surface roads and the sub way line do not run across multiple different zones. They run along the edge of a dense residential zone and end at my military base, defense contractor, airport and seaport area. Could there actually be enough "employment" in those places to cause most of the sims in the residential area to travel to them?

The roads and subways running between normal residential, commercial and industrial zones are mostly showing as moderate usage.

City population is now about 150,000. This is the best I have ever managed in 3000U but I know that congested public transportation will eventually kill a city.

Hummm. I have a garbage deal with a neighbor and the garbage is coming in through my seaport. Wonder if it is being moved to my waste to energy incinerators on the other side of the residential area through the subway system?

Going to try a surface rail line from the seaport to the incinerators and see if that does anything.

OK,
Added the surface rail line to a save before I had added the parallel subway line.

Only put train stations at the seaport and the incinerators. In one year this line went from no use to medium use and about 1/2 the subway sections between entrances went from aways congested to mostly heavy and the other sections alternated between heavy and congested.

This seems to indicate that garbage was being moved through the subway system and now most or maybe all of it is going by surface rail and did relieve some of the congestion in the subway.

Hehehe. If garbage was being moved by subway that would be stupid,, but,, no more stupid than not having hydro power or the ability to connect subway and surface rail systems together. Also not being able to build subways under rivers or lakes.