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Author Topic: Why must signalboxes only be placed on flat ground?  (Read 313 times)

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Offline freddyhayward

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Why must signalboxes only be placed on flat ground?
« on: July 27, 2020, 08:37:52 AM »
Is this restriction intentional, and if so, for what reason?

Offline jamespetts

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Re: Why must signalboxes only be placed on flat ground?
« Reply #1 on: July 27, 2020, 10:06:34 AM »
Is this restriction intentional, and if so, for what reason?

Signalboxes are types of buildings and this restriction applies to all buildings in Simutrans.

Offline freddyhayward

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Re: Why must signalboxes only be placed on flat ground?
« Reply #2 on: July 27, 2020, 10:44:15 AM »
Signalboxes are types of buildings and this restriction applies to all buildings in Simutrans.
I have checked the code, and there is a special case for signalboxes checking for flat ground. Players can build many other buildings, including headquarters and station extensions can be built freely on any slope. Most non-player built buildings (excluding fields, for example) can also be built anywhere.

Offline jamespetts

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Re: Why must signalboxes only be placed on flat ground?
« Reply #3 on: July 27, 2020, 11:15:33 AM »
I have checked the code, and there is a special case for signalboxes checking for flat ground. Players can build many other buildings, including headquarters and station extensions can be built freely on any slope. Most non-player built buildings (excluding fields, for example) can also be built anywhere.

I cannot recall specifically adding that code, but I did add the signalbox feature in 2015. I believe that I re-used quite a lot of code for signalboxes from other types of buildings, perhaps depots, and I know that I made the signalbox class inherit from the general building class. It may well be that the specific check comes from some of the code that I reused.

Of course, buildings cannot actually be built on non-flat land in Simutrans - buildings may be built on a tile that is not currently flat, but it is automatically flattened first.

Offline Freahk

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Re: Why must signalboxes only be placed on flat ground?
« Reply #4 on: July 27, 2020, 12:00:51 PM »
Signalboxes are types of buildings and this restriction applies to all buildings in Simutrans.
From a players point of view, this is not true!
Station expansion buildings can be built on slopes without a problem as well as industries, housings and so on can spawn in slopes, building a basement.
Not sure if that comes with any cost or not, but in any case the same behavior should apply to signalboxes. the player should pay for the basement in any case.



Another big isue of early time interval signals is it's range.
250m might be realistic, but the difference in between graphical and economical scale kicks in here again...

Tracks effectively have a width of 125m, so even a simple branch of a double tracked line into two double trackes lines cannot be signalled with a single signalbox, no matter where it is placed.
If we could increase it to a little more, I guess 375m, there would at least be exactly one "perfect" location to place the signalbox in order to control that intersection.

I guess this is one of the places where we need a good compromise in between economical and graphical scale with reality in mind.

I may have missed something. Maybe such intersections were usually controlled by 2-3 signalboxes in the real-world or something...

Offline Vladki

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Re: Why must signalboxes only be placed on flat ground?
« Reply #5 on: July 27, 2020, 02:53:14 PM »
I agree that fro gameplay reasons, the minimum range for any signalbox should be at least 4 tiles, i.e. 500 m.

Offline jamespetts

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Re: Why must signalboxes only be placed on flat ground?
« Reply #6 on: July 28, 2020, 10:23:44 PM »
In reality, there were not "singalboxes" in the 1830s. There were railway policemen, who carried flags (by day) and lams (by night) to control the trains (think of a police officer directing traffic at a road junction, only for railways). Before long, they were provided with huts where they could go to shelter from the rain.

After some time, the flags were replaced with various kinds of mechanical signals. These were usually operated by a lever at the base of the signals. Only later, in about the 1850s, was it thought sensible to concentrate all the levers controlling the points and signals for a given local area in one place, inside what was by then known as a railway policeman's cottage. The signalbox as we know it was thus born.

In these early days, we are still at the stage of flags and huts. It is likely that a substantial junction would require multiple policemen to control the trains, so needing to place two huts does not seem unreasonable (one per policeman). Data for the exact number of policemen needed in very early days is very hard to come by and may be entirely lost to history. If anybody is able to find clear data on this, that would be interesting.