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How do people use pre-signals?

Started by jamespetts, April 02, 2011, 12:18:19 AM

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jamespetts

Erik,

I thought that your signals reduced speed by half? Also, I wasn't aware that you had created more than one new type of signal (or is your single type of signal always capable of being a four-aspect signal?).
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Erik

I have made just one new type with three possibility's. (red [stop], yellow [slow down], green [go full speed])
The second graph gives a situation the train meets two times a signal is yellow and the third time red.

Reducing speed by half did seem a bit to radical.
If the signals stands a bigger distance from each other, the signal could make it worse.
Then reduce the speed by half till the next signal could be during longer than a total stop and pull up till maximum speed.
So I have made a formula where it give a maximum speed compare to it actual speed and the distance to the next signal.
signal_speed_limit = min( signal_speed_limit, cnv->get_min_top_speed() ) * ((double)next_signal/((double)next_signal+6)*0.7 + 0.2);
In other words
speed-limit-by-signal = actual-speed-limit * ( [next-signal / (next-signal+6) ] * 0.7 + 0.2 )
If the next signal is far away the speed limit will be reduced by somewhere at 10% but if the next signal is just a few tiles the speed limit will be reduced more. This all calculated from the yellow signal. (Not from the train.)

To prevent that a train has slow down to much. (That it nearly stand still.)
The maximum speed reducing is 75% of the maximum speed of the train.

Sorry for the confusion. It is a bit difficult for me to explain it right without writing a whole book. ;)


Djohaal

Keep in mind that kinetic energy is proportional to the Square of the velocity, so a reduction of 100 to 90km/h is much bigger than from 10 to 0 in terms of kinetic energy. Speed reduction should be managed on a non-linear fashion.

arnoud

Djohaal you're right. but by 100 km/h did you've more air resistance than by 10 km/h.

so it has a greater brake.

Djohaal

I might be wrong, but I think air resistance on ideal models is linear to speed, isn't it?

TheUniqueTiger

I had once suggested multi-aspect color signalling (MACL) for Simutrans about 3-4 yrs back considering association with reality but was promptly denied by Prissi because it would mean the rail network would move at a snail's pace with stops/starts due to traffic ahead & behind. So here I take this opportunity to voice my opinion again as most of you don't know what I had originally suggested.

A MACL signal (3 aspect) which shows red, yellow, green with appropriate graphics can be used as follows... (In India we use double yellow as well between green & yellow. (4 aspect) In my opinion 4-aspect signalling in Simutrans would be an overkill.

1. A non-branching stretch of track can have many MACL "auto" signals in place of normal signals. These just check whether the next block is free (yellow), and whether the next 2 blocks are free (green) and allow/reduce speeds accordingly and reserve the one/two blocks ahead. Red color behavior is taken for granted.

New suggestions are as follows:
2. The above pattern should use a different approach when approaching a signal which guards a junction ("control" signal). There should be a check if the junction is being approached by more than one train. In that case the train that has higher priority is allowed to pass (or may be higher speed) and reserve the one/two blocks ahead while the other comes to a halt at its respective control signal. This would decrease instances of a high speed passenger train being blocked at the last minute by a slow freight train which was waiting to cross a junction.

3. The signals which guard a junction can also have two directional projections (top-left or top-right or both) which show the direction where the train is supposed to go in case it branches off.

Thanks.

prissi

Did you even played OpenTTD. There you have many of such signals, and it is a complete mess for beginners. Forcing the player to use different signals in front of crossings is not good. Furthermore those aspect signals force a certain speed like 70 kph.

Simutrans is a transport simulation. Imho making a mode of transport too complex does not really balance such simulations. And your behaviour is already present in normal signals: If the next block is three tiles away, maximum speed is 200, two is 100 and one is 50. Thus if signals are two tiles separated they would impose a 100 speedlimit even two tiles before the signal. With a presignal you could extend this one block further.

Erik

It's true that for beginners the different types of signals is a mess.
But, would that be a reason not building new signal systems?


sdog

i wouldn't be surprised if the majority of people having played simutrans never found out how to an two trains on a line. That's not the people who read this forum, but those who played a couple of hours and at some point lost interest. See those point to point lines in online games all of the time.

going to more complex signalling is only a small step after hving understood signalling at all. It could be tried out in experimental. If it works well, you could just take it into trunk and turn it off by the pak set for new players (eg in pak Hajo).

arnoud


Erik

#45
I've been thinking.
Could a beginner mode or tutorial be an option?

When I begun with Simutrans the biggest trouble to begin was to make a vehicle at all.
I didn't know that I had to build a depot for it.
After discovering that the rest was quiet easy.
However there was only one type of signal then.

(I'm afraid it starts to get a bit off topic)

EDIT: I'm just finding that this already in discussion on a other topic. :D


paco_m

Quote from: prissi on April 14, 2011, 11:48:59 AM
Did you even played OpenTTD. There you have many of such signals, and it is a complete mess for beginners. Forcing the player to use different signals in front of crossings is not good. Furthermore those aspect signals force a certain speed like 70 kph.

As far as I know these "yellow" signals exist for 60 and 40 km/h, it is actually a speed limit (at least here in german and austrian railroads) that they are using quite often to avoid fullstops on high frequented lines.

As for the complexity of this I think it is harder to understand the current implementation of presignals in Simutrans as they have nothing in common with real presignals ;)
Anyway it would be a pakset decision, if you want to keep a pakset simple and beginner friendly just don't use such signals but why do you think it is a problem to allow it for other paksets that might be addressed to experienced players or players that know how real signals work?