Name: expanded river ports
Description : essentially turning the current 1 level river port into 3. (river trade post, river port, large river port)
Effects : improve tradition significantly, improve happiness, reduce law and reduce public health. (greater chance of diease in long distance contact)
What factions can make it : all
What events, if any, are required to make it : i set up a large_river hidden resource in addition to river... and now most settlements have river anyway (i think around 60-70%) . but only a few have large river. highest level require large river to build, effects of lower level onces is also a bit higher with large river settlements.
Cost: first level very cheap, 800, second level around 1600, third 3200
Time to build (at 1TPY) : 2, 4, 8
Settlement level required : town , large town, city
Castle/city/both: both
A good image for the building browser (if you have one) : nope. I know a few good onces but were denied of permission to use them.