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Author Topic: Brick Viaducts Pricing/Weight Limits  (Read 643 times)

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Offline SuperTimo gb

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Brick Viaducts Pricing/Weight Limits
« on: September 24, 2018, 05:42:35 PM »
Not sure where to put this as this isn't a bug, more an oversight (or balancing issue) perhaps.



The red brick elevated track can only support 90t whereas the wooden trestle can support 150t which doesn't seem right. The red brick elevated track can also support less weight than the stone elevated track that precedes and, in addition to this, the matching red brick bridge can support 400t and the 'orange' brick bridge can support 1500t.

Is this intentional or is it an error in the tooltip? By this game period (1850s) trains easily weigh more than 90t and when trying to build routes using the red elevated track they seem to cause routing errors. However I have them in several areas where trains are >90t and there doesn't seem to be issues.

On another note, in real life I don't think the colour of the bricks affects their weight carrying capability (I understand the difference is to do with balancing bridges at different times). Could it be possible to have an option to choose the material used for the bridge (brick colour or stone) and standardise the railway viaducts until the use of concrete in the 1950s? Many of the original brick arch bridges built when railway lines were first built are still in use today (although many have adjacent spans and other modifications) and the choice of material was more to do with what was available locally. So in London yellow stock brick would be used for example.

If this is feasible, or as a balancing exercise in general I could do some research into the costs of railway bridges overt time if needed? At the moment it is much cheaper to build a bridge than an embankment which shouldn't be the case in the Victorian era, I think increasing the prices of stone/brick viaducts substantially would encourage more realistic use of earthworks rather than bridges.

Offline DrSuperGood

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Re: Brick Viaducts Pricing/Weight Limits
« Reply #1 on: September 24, 2018, 09:21:08 PM »
Quote
The red brick elevated track can only support 90t whereas the wooden trestle can support 150t which doesn't seem right.
From what I understand the dark red brick is meant to represent early hand made bricks so are very flimsy. The wooden trestle is meant to be stone/brick pillars with wood between them so is slightly stronger. The bright red brick elevated way are industrially fired and quality controlled bricks so are the most strong.
Quote
in addition to this, the matching red brick bridge can support 400t and the 'orange' brick bridge can support 1500t.
Bridges weight is different from elevated ways. Elevated ways are the weight per tile of vehicle over them. Bridges are the total weight of all tiles of the vehicle.

Offline SuperTimo gb

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Re: Brick Viaducts Pricing/Weight Limits
« Reply #2 on: September 25, 2018, 04:05:17 PM »
Quote
Bridges weight is different from elevated ways. Elevated ways are the weight per tile of vehicle over them. Bridges are the total weight of all tiles of the vehicle.

Ah this would explain why the elevated ways seemed to be able to hold >90t. Is it a limitation of the engine that bridges are modelled like that? That makes sense for truss bridges where the main span is unsupported for several tiles but for brick viaducts each tile is supported.

By the 1850s I would have thought that brick making would be mature enough to produce high quality bricks just perhaps not very quickly or cheaply. Either way bricks, even low quality ones, are very strong under compression which arched bridges take advantage of. Even if the bricks were poor quality higher quality bricks, or stone, were used in important areas such as the key stone (the older red brick elevated way even has stone detailing on the arches). Brunel's Maidenhead Bridge, constructed in 1838, is still in use today (though it was widened in the 1890s) and has a particularly flat arch showing how arch bridges take full advantage of the strengths of bricks.

Perhaps it would be better if the stone elevated way was available for longer? Asides from looking ugly the wooden elevated way also has a very low speed limit so you are more limited in 1850 then you are in 1830 when it comes to building elevated ways. The brick viaduct does have a higher speed limit but it is not until the 1870s that trains are capable of consistently achieving speeds of >80km/h, and since elevated ways are usually built in urban areas near stations this is not much of a limitation.

I have created a spreadsheet on the different elevated ways available throughout the game which you can see here: https://drive.google.com/open?id=1kxCKNeyE9hnXBwdFXJ2bVo-aqox515ebXiVdGtUqhQo (note that the figures for earthworks are for 2 unit high embankments.

As I mentioned before I think that elevated ways and bridges are far too cheap in relation to earthworks. Particularly in the early game where an embankment costs nearly 4 times as much as stone viaduct, and at this point in time the infinite weight and speed limits are irrelevant as no trains are anywhere close to being limited by the stone viaduct, also there is the additional cost of laying track on the embankment and, in urban areas, demolishing buildings. This is ignoring how much cheaper bridges are than embankments which is even more ridiculous. Civil engineering in the Victorian era should be very very expensive at the moment i think it is far too cheap to bridge your way across everything.
« Last Edit: September 25, 2018, 10:15:31 PM by SuperTimo »

Offline jamespetts gb

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Re: Brick Viaducts Pricing/Weight Limits
« Reply #3 on: September 25, 2018, 11:04:08 PM »
Thank you for your thoughts. The differences in the strength of bridges is not just in the colour of the bricks - the colour is simply used to give a visual representation of the differences: it is in the type of brick used and in the design and standard of engineering of the structure overall. Stone bridges are intended to be stronger (but more expensive) than early brick bridges as they were in reality.

Dr. Supergood is correct as to the inherent differencs between bridges and elevated ways: bridges are modelled in the game as an object separate from the underlying way (so that the bridge can have a weight limit separate from the railway/road that goes accross it), but elevated ways are just a special type of way, where this is not possible. This is a limitation inherited from Standard: ideally, bridges and elevated ways would be treated in the same way, but it would require a huge amount of very difficult work to achieve this and there are many years' worth of higher priority tasks at present.

As to the actual figures, if you can find detailed data on the weight bearing properties of brick and arch stone bridges of the early and mid 19th centuries, then that would be very helpful, and I could use it to improve the in-game balance.

I have taken your suggestion of putting back the retirement of the masonry elevated ways to 1865, 5 years after the introduction of the iron elevated ways so that there is no period in which players are confined to using the wooden type.

In relation to the comparison in cost with earthworks, this will have to wait until full balancing can be achieved, which is some way off given the features necessary for this. However, when considering the difference in cost, one important thing worth bearing in mind is that bridges and elevated ways have ongoing maintenance costs, whereas, in Simutrans at least, earthworks do not, so this must be taken into account in setting the prices of each.

Offline SuperTimo gb

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Re: Brick Viaducts Pricing/Weight Limits
« Reply #4 on: September 28, 2018, 03:21:28 PM »
I have been looking for info on bridges and so far any hard numbers are pretty scarce. I found a paper, titled 'Train Loads on Bridges 1825 to 2010', which has been cited quite a lot but unfortunately it is located behind a paywall. https://www.tandfonline.com/doi/pdf/10.1179/175812111X13033852943273?needAccess=true

I will have a look for some other sources, I asked a friend of mine who is studying at my old university if he can access that paper and he was unable to despite logging in through Shibboleth. If anyone else has a way of accessing it, it would be most useful.

Offline Vladki cz

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Re: Brick Viaducts Pricing/Weight Limits
« Reply #5 on: September 28, 2018, 08:25:14 PM »

Offline jamespetts gb

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Re: Brick Viaducts Pricing/Weight Limits
« Reply #6 on: September 28, 2018, 10:44:18 PM »
This article seems to be free

https://www.tandfonline.com/doi/full/10.1179/1758120613Z.00000000037?src=recsys

That is interesting, although it seems very general, and does not give numerical details of maximum loadings, etc.