How to fix the "Not enough goods to sell" problem

I've created a dozen cities in Skylines so far, but in my latest city, I've encountered a new problem. A lot of my Commercial buildings report the problem "Not enough goods to sell".

From my understanding, it seems like the Goods in these Commercial buildings are selling out too quickly, and not being replenished fast enough.

Here are the ways in which a Commercial building can replenish goods, and my response to each one, in my particular game:

• Trucks. They bring in goods, via the international highway. My traffic is really good, so this shouldn't be a problem.
• Trains. I've got one train station, since the railway is pretty far out from my city, so I had to extend my city just to reach this one station.
• Ships. I've got four cargo docks, and it still doesn't seem to be enough. Most ships coming in are 100% full. Although I've started to notice a few are less than 50% full, which I thought indicated that my city had more supplies than necessary.

Is there anything else I'm missing? I've also got no Policies enabled regarding Commercial zones.

Edit 1: I have no Industrial zones, because they cause pollution and traffic, and because my citizens are too educated. About 10% are "Uneducated". So most of them work in Offices instead, and I have a ton of them.

I don't think my city has a high demand for Commercial zones, because I currently have a 10x10 Commercial plot that isn't developing. I tend to manage my zones pretty well, I think, meaning I will almost always have one empty lot for each zone type. This allows me to control growth, because if that empty lot does not develop, then that's fine because it is there just in case the demand ever increases for that particular zone type. And if the zone does develop, then I make a new empty lot.

My traffic is flowing quite nicely. It's not all green, but there are definitely no red spots at all; orange, at worst. And lots of highways, which my citizens happily take if they need it, which they use quite frequently. I don't think traffic is a concern; the heart of my city isn't even that far away from my four cargo harbors.

Solution 1:

I haven't found any (official) evidence to prove my hypothesis following now, so be aware that it might be wrong.

You say that you have no industrial zones at all. So, let's check this chart first:

You see that there's a production chain which requires specialized and generic industry to create goods for your commercial buildings. If you had that, you could easily lower the import rate. However, you don't have those buildings or zones so basically you import everything. You can read here too that offices are a clean alternative to industry, nevertheless they don't produce any goods.

• First off, there could be an unknown import cap. Really unlikely, but possible.
• As stated here, import trucks, ships or trains don't use the nearest entrance to your city. They spawn wherever they want to. So some trucks could be already on their way, however, they're taking ages since they have to drive through your whole city. That, too, would explain why some ships just have cargo of 50%. Maybe there are still boats on the sea coming from the bottom end of your map to your upper end. In the meanwhile, other ships spawned recognized that they don't need 100% cargo because other ships already have the cargo.
• Also, do your commercial buildings import at all? Stated here again, some buildings not connected to any industrial area nearby do most likely not import stuff.

I guess the whole problem is that you miss industrial areas. Your problem isn't well documented nor reported because it doesn't occur that often. Most cities have industrial areas, you and few others don't have them and are suddenly facing the problems of too less goods. As you can also see here, offices have some downsides:

• Fewer jobs.
• No goods.
• Less commercial tax income.

As a fellow city builder, I can just recommend you to build up some industry. The flow will be way better and less troublesome. Yes, you have pollution. Just be a dirty (real life) mayor and hide anything negative from your citizens by placing it far away from them and covering it up.

As said in the beginning, I don't have any official evidence supporting my hypothesis, but I hope I could still help you with it.

Solution 2:

Just remember if you do add more generic industry to combat this you will have to be able to import the raw materials effectively. I find harbour to import to generic industry then rail to commercial. Effective passenger rail will also elimante as much 80% commute taffic off your roads.

Solution 3:

I've found that trucks can despawn coming right out of mass transit (trains/ships). Ships and trains can come into harbor/stations faster than they can get the cargo out and you may have a ton of cargo backed up in the transit system and despawning either in the station or right out of it.

I've had similar problems and found adjustements to the road system that resulted in better flow and suddenly everyone is getting their imports.

Solution 4:

I think it may be a need for generic industry products try building those or increasing imports(this is just a guess though).