Re: [WIP] YAAM - Yet Another Acceleration Model
Posted: 13 Nov 2016 00:47
Few things, starting with a crash report:
Game crashed as I over built a station tile with a different style platform. Station was attached to an airport. Not sure if that is helpful.
Other things I have noticed:
The YAAM accelleration model is very slow, even with modern, powerful trains. This is probably intended, for realism or otherwise, but it poses some scale problems on smaller maps (512 and below). If playing an original, 256^2 sized map, with a normal town and industry density, distances between junctions or stations are small enough that trains will spend a large amount of their time accelerating or decelerating. I understand this is part of the challenge, but it becomes extreme to the point of un-fun on compact maps. Not sure if a setting to change acceleration strength would help or not.
Compounding the above; when industries or towns are closer together, branches off the mainline become closer together. Due to OpenTTD's scale, we can't really space junctions several miles apart. With a long reservation ahead, more and more of the track near a junction becomes 'interlocked', with distant trains able to reserve a path that blocks traffic in both ways on the mainline, and delays cascading to affect other junctions. As trains take longer to re-accelerate from a red or yellow, busy trunk lines trend towards speeds stuck between 40-70 km/h. This can be partially relieved by making all junctions grade separated, but the point where this becomes necessary arrives much sooner than normal. Furthermore, it seems sort of contrary to the spirit of careful, realistic track design intended by this patch. It also means that mixed traffic or branching service is discouraged, whereas one of the dreams of having yellow signals in game is smoother integration of slow and fast trains.
It is still very difficult to run single track sections of any kind. A completely isolated single line with a single train will run at 15 km/h the entire time. It is not the end of the world to fill such a line with signals, but it does feel odd. Simple branches off the mainline are awkward both for trains entering or leaving, as the train will slow to yellow speed before it leaves the mainline and proceed along the entire branch as if about to stop. Even when the branch is small compared to the distance traveled on mainline, it can have a huge impact on journey time (see attached image) Adding signals for the train entering the branch has the danger of letting a following train down and trapping the first on the branch line. Single track also has the issue that it is normally not signaled except for passing loops, so reservations can extend and block track much farther and earlier than desired, or end up with a train travelling a huge distance at reduced speed. It might be helpful to add a 'distant' signal, without a red aspect, that does not serve as a possible stopping point for trains, but does warn them of need to reduce speed ahead. This would let trains do their deceleration off the mainline, near the actual end of line, without trapping other trains.
Lastly, at stations; trains try to reserve a long path ahead if able, even when stopping at a station. At certain types of terminus, or where two tracks merge just past the station, this means a train can block a significant distance ahead for a long time while it loads. This can lead to a stopped local train blocking an express passing through, or a loading train blocking the station entrance at end of line. In the attached image, the northern DMU has reserved track out onto the station throat, and will prevent the other DMU and scrap metal train from leaving, as well as a hypothetical train from entering. Additionally it is possible that one of these trains arriving from the north could trap a train in the depot. I'd suggest enforcing that reservations end at visited stations, and further reservations are not requested until the train departs.
An observation: diesels produce a ton of smoke while braking - hopefully they are not trying to use thrust reversers!
I still don't know how to treat block signals... unlimited speed at your own risk? two-aspect red/yellow only?
I hope this is helpful input, please don't take it as a complaint! Let me know if you want me to draw more signal types!
Game crashed as I over built a station tile with a different style platform. Station was attached to an airport. Not sure if that is helpful.
Other things I have noticed:
The YAAM accelleration model is very slow, even with modern, powerful trains. This is probably intended, for realism or otherwise, but it poses some scale problems on smaller maps (512 and below). If playing an original, 256^2 sized map, with a normal town and industry density, distances between junctions or stations are small enough that trains will spend a large amount of their time accelerating or decelerating. I understand this is part of the challenge, but it becomes extreme to the point of un-fun on compact maps. Not sure if a setting to change acceleration strength would help or not.
Compounding the above; when industries or towns are closer together, branches off the mainline become closer together. Due to OpenTTD's scale, we can't really space junctions several miles apart. With a long reservation ahead, more and more of the track near a junction becomes 'interlocked', with distant trains able to reserve a path that blocks traffic in both ways on the mainline, and delays cascading to affect other junctions. As trains take longer to re-accelerate from a red or yellow, busy trunk lines trend towards speeds stuck between 40-70 km/h. This can be partially relieved by making all junctions grade separated, but the point where this becomes necessary arrives much sooner than normal. Furthermore, it seems sort of contrary to the spirit of careful, realistic track design intended by this patch. It also means that mixed traffic or branching service is discouraged, whereas one of the dreams of having yellow signals in game is smoother integration of slow and fast trains.
It is still very difficult to run single track sections of any kind. A completely isolated single line with a single train will run at 15 km/h the entire time. It is not the end of the world to fill such a line with signals, but it does feel odd. Simple branches off the mainline are awkward both for trains entering or leaving, as the train will slow to yellow speed before it leaves the mainline and proceed along the entire branch as if about to stop. Even when the branch is small compared to the distance traveled on mainline, it can have a huge impact on journey time (see attached image) Adding signals for the train entering the branch has the danger of letting a following train down and trapping the first on the branch line. Single track also has the issue that it is normally not signaled except for passing loops, so reservations can extend and block track much farther and earlier than desired, or end up with a train travelling a huge distance at reduced speed. It might be helpful to add a 'distant' signal, without a red aspect, that does not serve as a possible stopping point for trains, but does warn them of need to reduce speed ahead. This would let trains do their deceleration off the mainline, near the actual end of line, without trapping other trains.
Lastly, at stations; trains try to reserve a long path ahead if able, even when stopping at a station. At certain types of terminus, or where two tracks merge just past the station, this means a train can block a significant distance ahead for a long time while it loads. This can lead to a stopped local train blocking an express passing through, or a loading train blocking the station entrance at end of line. In the attached image, the northern DMU has reserved track out onto the station throat, and will prevent the other DMU and scrap metal train from leaving, as well as a hypothetical train from entering. Additionally it is possible that one of these trains arriving from the north could trap a train in the depot. I'd suggest enforcing that reservations end at visited stations, and further reservations are not requested until the train departs.
An observation: diesels produce a ton of smoke while braking - hopefully they are not trying to use thrust reversers!
I still don't know how to treat block signals... unlimited speed at your own risk? two-aspect red/yellow only?
I hope this is helpful input, please don't take it as a complaint! Let me know if you want me to draw more signal types!