Is there a way I can assist the AI in being better about its town/city expansion? Currently the cities look a bit disjointed in terms of road connectivity.
Personally, I prefer a simpler method:
In Advanced Settings, there's a setting to control the town roads: 2x2, 3x3, Original or Improved.
Personally, I always play with 2x2, because it fits neatly with my network of rail; and when playing using a 2x2 or 3x3 grid layout, the city placer during generation will align all cities on the grid, meaning that as cities grow, they will join together neatly.
The setting is found under
Also of interest is
if you insist on building the grid yourself.
Omokoii raises a valid point: Using the 2x2 grid does consume a lot of space and slows down city development, because more growth cycles are dedicated to growing roads.
However, a workaround exists for this: Increase city growth speed; essentially reclaiming the lost growth cycles:
Depending on your play style, grid size and other factors, either "Fast" or "Very Fast" might be suitable.
If the issue is one of station catchment areas, my answer to this question might be illuminating, especially the second method regarding non-adjacent stations.
Here's how I do it, basically just make sure you build and own all roads in the city.
The point of constructing the road grid yourself is that the AI have a tendency to waste a lot of space, putting roads where it instead could put buildings that generate traffic/profit.
Also buy any land where you plan to build roads when the city expands even further. To limit the expantion of the town you can surround it with bought land that you sell off when you are ready to expand.
I feel it's better to build your own road network. Certainly, turn on the so-called 3x3 grid, which places initial roads on tiles any multiple of 4. But Advanced Settings > Economy > Towns > Towns are allowed to build roads: OFF. Then build to the grid.
After all, roads are cheap enough to build and then you decide where and when. Also, you have rights on your own company-owned roads that you may not on town-owned roads (depending on other settings) or roads owned by competitors.
If you're serious about the town grid, be prepared to do a little landscaping; which may require some demolition of existing town roads and buildings. Ideally, the grid is flat; next best is a steady, smooth, gradual incline. If you're running a lot of local bus service you'll want to make sure roads connect at all junctions; and irregular topography frustrates this. Keep Local Authority happy by making changes slowly and meanwhile providing plenty of service. After a round of landscaping and road building, Purchase Land ('u' hotkey) strategically to forbid new buildings in places where you'll want to do more landscaping after the locals have cooled off. This will also keep grass, trees, and farmer's fields from growing on newly bared land; so limiting your costs.
One especially exasperating feature is the tendency of towns to build useless bridges that block grid-aligned expansion. If you have the money and a good local rating, demolish these, landfill the water, and complete the grid.
If you do allow towns to build roads, I strongly suggest you at least turn Advanced Settings > Economy > Towns > Towns are allowed to build grade crossings: OFF. Otherwise you may have frequent road/rail crashes and these look bad to the locals. Expand the road grid across rails with bridges or tunnels; town will not do this.