1) Traffic Lights: my vehicles seem to ignore green lights. Are TLs any use?
This should not happen.

If there is space on the other side of the junction, the vehicles should proceed.
Maybe check that there are no one-way roads? Use the colon : key to see them.
If that does not help, please give me the co-ordinates (on Discord?) so I (or another player) can investigate.
2) I found large local savefiles from the server game. Are they good for anything?
When you join an online game, the server transfers the save and then the client loads it. Afterwards, the saves are only for useful for testing things offline.
But that might be helpful in your situation. When I first started playing on Bridgewater-Brunel, I had terrible lag, so I tested all my building projects offline first. If you don't want to do that, you can safely delete all the .sve files after you have finished playing.
Also, I think the client saves the game every time you exit. If you don't want this, create a simuconf.tab file in your home directory's /simutrans subdirectory and add
reload_and_save_on_quit = 0
3) My player colour is reset every time I log on. Why?
OK, it seems that player colours are bugged at the moment. I will file a bug report.
4) I have bought a DAF CF for bulk fluids. Max. Axle Load is 12t. I've set a schedule with the first waypoint a couple of tiles away - but it can't even leave the depot (2547,2125). The roads are all modern.
Waypoints are bugged at the moment. Unfortunately we have to build stops instead of waypoints. Try using stops of the 'wrong' type (e.g. for your bulk fluids, use a passenger stop) because this will minimize the stop loading time.
5) I suppose there is no way to refit my hovercraft with mail space?
Sadly there are no mail hovercraft in this year (though there were earlier, IIRC). But the new catamarans can carry mail as well as passengers.
6) Is there any explanation in the forum for how far mail "walks" to a postbox, or how line speed affects mail being created?
Sorry, I don't think so.
The
Extended overview explains the basic features of mail.
I don't know for certain how far mail "walks" to a postbox. But if you click on a building you can see "Stops potentially within walking distance" and the limit for that tab is 4km, so I guess 4 km?
Mail is created for a particular destination. The mail will use the player line(s) with the lowest journey time to that destination. If the destination cannot be reached by any player route, the mail is not created.
7) I have a slightly older laptop with 8GB RAM and two Intel cores (~2 Ghz IIRC). My CPU is at 70% and my RAM at 80%. But the game lags pretty badly.
I feel your pain! I know the lag is very, very frustrating. This was my situation until James kindly reduced the server speed a few months ago.
The usual measurement of lag is 'tree-planting time'. Use the Special Construction Tools to build a tree and time how long it takes to appear on the map. How bad is your lag when you join? How bad after a few minutes?
8GB should just be enough, if you are not using any other programs. But Bridgewater-Brunel is set to use 6 threads, so a 2-core PC will find it difficult.
The server is supposed to adjust to the speed of the players' PCs, but this is a new feature and I don't think it has been tested very well.
Some things you can do to help:
- Turn off water animations. In your home directory's \simutrans\ directory, make a simuconf.tab file and add
water_animation_ms = 0
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- If you don't listen to the in-game music, you can use start the client with the "-nomidi" parameter, so that it does not load those files.
- In the same way the "-nosound" parameter will run the client without sound, which might give you a little more performance.
- Make the game's window as small as you can and zoom in as much as possible.
- Try not to use the minimap and especially don't use the Network Mode. The Network Mode generates a lot of lag. When my PC struggled, I tried to only use Network Mode offline or just before I logged off.