I've spent a lot of time this past week trying to really understand the SLRR system in Bellisseria. I've made some mistakes, and had some good interactions and advice from @Squeaky Mole, our current railroad baron and technogician! If you want to drive trains/trolleys/trams etc. around the rails in Bellisseria, here are some general tips and advice.
Note that we also have an in-world group named Bellisseria SLRR Riders that you can join for chat, advice, asking around whether some area of track might be bugged, setting up group outings/tours, and so on. secondlife:///app/group/eaf057e4-2194-3b1e-6bf1-5ea819ca4250/about
Helpful tips and advice
The SLRR system in Bellisseria is still in a state of development, so there might be some buggy switch lights at certain branches at any given time. If you're reasonably certain that a switch isn't working correctly, reach out to Squeaky Mole and as time permits they'll try to debug it. (You can also report a possibly broken switch here in this thread and others can try to test and corroborate that it's broken.
Generally, switch lights that are red or green indicate a section of track that is finished and should be working correctly. These sections have switching logic that is meant to keep only one train on a single track section at a time, so that there are no collisions. (Although many trains run phantom so you won't actually collide in many cases.)
However, switch lights that are orange indicate unfinished sections of track. There is no switching logic here, and you travel into an orange section of track you might encounter other trains or unfinished sections that loop or terminate in unpredictable ways. However, some of these might eventually merge back into finished sections of track, so don't be afraid to explore sections that are currently in an "orange" state.
You should NOT rez your train just anywhere random on the track! (Like, in your house parcel and then sliding the train over onto the track.) Doing this will break the switching system and mess up other trains that might be on the tracks. You should only rez your trains in one of the designated rez zones on the track itself (listed further below). This ensures that the switching system is aware of your train and tries to coordinate your movement correctly to avoid collision with other trains in the finished track sections.
You should NOT "side-edit' your train onto a parallel track (or further ahead in the same track) near a switching section to force your way through a RED switch light! Instead, just stop and wait for the light to turn green! The switching system turns the lights red and stops your train when there is a train somewhere on the section ahead of you--even if you can't see it when camming ahead, or by looking for green dots on the big map. There are hidden sensors on the approaches to every switch, and if you start approaching on the correct side (per flow of traffic), but but then in the middle side-edit yourself over and approach the other incorrect side, you'll break the switch logic in that region and adjoining regions for a period of time. (There is an automatic safety reset to fix such broken switches eventually.)
Therefore, be patient at red lights! You're sharing the track with other people! You might need to sit for 5 minutes (or more) while you wait for the section ahead to clear and the light to turn green! Even if you open the big map and look for green dots along the track in front of you, trains will usually not be visible. The switch light isn't potentially broken unless you sit there for 10-15 minutes or longer and the light never turns green.
Don't pause your train for a long time on the tracks (or at stations). When you are in a track section, you are preventing the switching system from letting others into that same track section. So don't just sit still on a section of track for longer than necessary to let new passengers get on/off at a station or whatever. Keep the lines moving, so that you aren't keeping other trains stuck waiting at red signal lights any longer than necessary!
Watch the signal lights as you approach them and check their state from fairly far away. Because of typical region/browser lag, the signal light ahead might be green while you are still 40 meters away, but turn red as you get closer to it. Your train should still move through the switch okay when this happens; it's just lag causing the light turn to turn red (affecting the next train behind you) before you've had time to pass through yourself.
Most SLRR trains will automatically snap over to the track and twist themselves to face in the correct 'flow of traffic' direction when you rez them out in a designate rez zone next to the track. Just hop in and go!
Some rez zones will allow you to exit in either direction. For example, if you rez a train and the light in front of the train is red, but their is another light behind you that is green, you can flip your train and just head out in the direction of the green light if you don't want to wait for the original light to turn green.
There are some "Y" intersections where you have user control over which direction you take through the intersection. These typically have a small round green/red metal switch sitting about 6 feet off the ground near one side of the switch light. If present, you should be able to stop the train and touch them to change the rail switch there to take you in the direction you want to go. Watch the little red/white semaphore flags near such switches to tell which direction the switch will take you. When the semaphore is tilted upward, that indicates which track you'll follow if you pass through the intersection.
Rez zones (at the date this was posted)
West side of lower Northern Bellisseria, just above the sandy beach camper area http://maps.secondlife.com/secondlife/Pugwash/199/48/23
Extreme south-east corner of Southern Bellisseria http://maps.secondlife.com/secondlife/Red Hook/94/147/34
Those are the basics for now! Join the group so you can chat with other engineers that might be on the tracks with you! Be patient with our fine moles (and especially with Squeaky Mole) if you encounter bugs. The moles are juggling a lot of priorities as they build out Bellisseria and the rail system isn't always the hot priority at any given moment.
See you on the tracks!