Building trams tracks sometimes randomly not possible

[Sirius]

Hey there, when a player has built something, e.g. trolleybus wires at a public road, it is randomly somethimes not possible for another player to build tram tracks at that same tile.
The exact case just happened at stepehnson-siemens:
- A Player (EOE) has some trolleybus lines in a city.
- We share acces with ech other.
- I was about to build a lightrail network in that city, which worked fine until suddenly I was not able to build on.
- Dragging again and again to the same tile will sometimes allow and soetimes deny building.
- Further, public roads with foreign bus stops on it will entirely deny building if dragged to that exact tile, while dragging through it is fine.

[jamespetts]

Thank you for the report. Are you able to give instructions for a reliable reproduction case for this? It is not likely to be feasible to attempt to fix this without a reliable reproduction case.

[Sirius]

Please be patient, as always I report located bugs as soon as I encounter them, so I don't forget, and later on update with any data I could collect about it.

The second one is just as simple as described.
1. build (or locate) any public (unowned) road.
2. build a bus stop on top.
3. try to drag tram rails to that same tile, it won't be possible but dragging through is just fine.

The first one is more difficult, but I guess I got it relyably reproduced (see the attached save), all actions assume you are playing as Player 1 (who does not share any permissions with default player)
At first, locate default players trolleybus wires, note some of them are at public roads but the end is at default players own road. There will unexpected behavior in the following cases:

1. Drag a tram rail along the public road and you will notice:
  - When default player has a trolleybus at that tile and there is a vehicle at that tile, no matter if private car or default players bus, you won't be able to drag to that tile. This is also independant of access sharing.
  - When default player had a bus stop at that tile you won't be able to drag to that tile. This is also independant of access sharing.
2. drag a tram rail along default players road and you will notice:
  - It's not possible, no matter if sharing access or not.
3. drag from a public road with default players catenary to public players road without catenary and you will notice:
  - It's possible! No matter if sharing access or not.

Now look at the numbered pieces of track and let's try building level crossings (normal rail, instead of tramways)
For each number, try to build a level crosssing, when sharing permissions, one time dragging onto the road  and one time dragging through directly. Do the same without sharing permissions again.
You will notice the following:
- Sharing permissions won't allow for dragging onto another players road with trolleybus wires but dragging through is always fine.
- Further, sharing permissions won't allow dragging onto public road with another players trolleybus wire, if there is any vehicle at that tile but dragging through is fine again.
- Dragging onto a dead-end road is fine, while dragging through is not, no matter if sharing permissions or not.
- Without sharing permissions, it is still posible to drag onto another players road, but it's not posssible to drag through.
- Further, dragging onto a dead-end road is fine, whereas dragging throgh at a dead end road is not.

It seems our trolleybus wires are a too restrictive, while roads without are too nice.
What I would expect for both, tram and rail (level crossing), is the following:
- For public roads, building tracks is always possible, no matter trolleybus wires and independant of vehicles being at that tile currently.
- If sharing permissions, building track at player owned roads is always possible, that means no matter trolleybus wires and dragging onto or through, also no matter of bus stops in case of tramways.
- If not sharing permissions, building rail at player owned roads is always impossible.
- If not sharing permissions, one could discuss about an exception for tramways along the player owned road for gameplay reasons, as this does not affect other players vehicles. However, from a real-world standpoint one would not be allowed to build a tramway at a privately owned ground without permission of the owner.

[jamespetts]

Thank you for the details: that is most helpful. I will have to look into this when I get home.