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Simutrans Extended => Simutrans-Extended paksets => Pak128.Britain-Ex => Topic started by: freddyhayward on September 20, 2021, 04:39:53 AM

Title: railway height clearance
Post by: freddyhayward on September 20, 2021, 04:39:53 AM
Is it intended that all railways have a height clearance of at least 2 tiles? This makes the double-height requirement for the SR-4DD meaningless.
Title: Re: railway height clearance
Post by: Spenk009 on October 18, 2021, 01:15:09 PM
I was under the impression that older tracks could be laid under low bridges, but it only appears possible for tram tracks on old roads where the bridge is built after the road and tram track are laid.
Title: Re: railway height clearance
Post by: Sirius on October 18, 2021, 04:37:56 PM
Besides that, the SR-4DD is not even the tallest one on British rails, but the only one (I am aware of) using that constraint.
According to Wikipedia SR-4DD is 3.89 m tall.
The Eurostar E320 is built to the continental loading gauge and is 4.34m tall.
The flirt UK (Class 745 and 755) is 3.95 m tall.


The high-clearance-under-bridges thing seems to a bit messy anyways.

Looking at busses and trams, London Tramlink flexity swifts are 3.67m tall and do not have the high clearance flag.
Most modern trams are roughly 3.6m tall.
Back on rails, sub-surface stock is somewhere between 3.6m to 3.7m tall depending on the exact class.
The Pendolino is just 3.56m tall.
DLR stock is roughly 3.5m tall.
Tube stock is even just 2.9m tall.
None of these can pass under low bridges, because such bridges cannot be built, except if running on unconstrainted tram tracks.
Title: Re: railway height clearance
Post by: Vladki on October 28, 2021, 02:53:42 PM
how about the double decker blackpool trams?  Do they require higher clearance than modern trams and trains?
Title: Re: railway height clearance
Post by: Sirius on October 28, 2021, 03:26:26 PM
You really cannot stack two decks at 3.6m. This would result in less than 1.8, practically rather something around 1.5m per deck.
It is really difficult to find technical data about these trams, but the blackpool standard coach from the 1930s is roughly 5m high.
Title: Re: railway height clearance
Post by: Vladki on October 29, 2021, 07:12:26 PM
Also the height of overhead catenary may be higher in blackpool that on "normal" tram and train lines.

Anyway I think that at least for trams, the same distinction as for buses could be used. Double deckers need high clearance, single deckers can pass under half height clearance.

Tube trains and narrow gauge also should be able to pass low clearance bridges.
Not sure about standard trains

https://www.onemanbrnoblog.cz/zeleznicni-naspy-a-viadukty-jako-novodobe-hradby-v-rozvoji-mesta/

The first photo on the above page is a bridge in brno. Clearance 3.3 m, passable by single deck buses, trams and trolleybuses. That could be used as a sample for half height bridge
Title: Re: railway height clearance
Post by: jamespetts on December 31, 2021, 10:47:53 AM
Quote from: freddyhayward on September 20, 2021, 04:39:53 AM
Is it intended that all railways have a height clearance of at least 2 tiles? This makes the double-height requirement for the SR-4DD meaningless.

I should note that the SR 4DD trains were built to fit into the standard structure gauge, which is why they were so cramped and uncomfortable (and also so innovative). The is_tall flag does nothing useful on railways, where there is a standard structure gauge and most modern trains are designed to reach the limits of that gauge so as to maximise internal space.
Title: Re: railway height clearance
Post by: PJMack on April 15, 2022, 10:50:36 PM
Quote from: Sirius on October 18, 2021, 04:37:56 PMThe high-clearance-under-bridges thing seems to a bit messy anyways.

Looking at busses and trams, London Tramlink flexity swifts are 3.67m tall and do not have the high clearance flag.
Most modern trams are roughly 3.6m tall.
Back on rails, sub-surface stock is somewhere between 3.6m to 3.7m tall depending on the exact class.
The Pendolino is just 3.56m tall.
DLR stock is roughly 3.5m tall.
Tube stock is even just 2.9m tall.
None of these can pass under low bridges, because such bridges cannot be built, except if running on unconstrainted tram tracks.
I do have a PR open that allows low bridges to be built over rails and half height tunnels as discussed here: https://forum.simutrans.com/index.php/topic,21508.0.html (https://forum.simutrans.com/index.php/topic,21508.0.html).  To summarize for this post: rail vehicles would be tall by default, building low bridges over rail would require ownership and holding the shift key down, and half height tunnels would need to be added to the pakset.

If the PR is approved, the question then becomes how to define what rail vehicles are not tall.  Thinking is that all heavy (non-tram) rail vehicles would be considered tall except for the district stock and tube stock, as those are some of the shorter vehicles in the pakset.  I think that for trams and road vehicles the current system, single deckers being non-tall and double deckers being tall, is working as it is clear to the players and not too ungrounded in reality.  I don't think anyone wants to looking up the height of every single vehicle in the pakset.
Title: Re: railway height clearance
Post by: Sirius on April 15, 2022, 10:59:37 PM
As a concept related to isTall is implemented using way constraints, a constraint mapping in simuconf might be sensible, so all rail vehicles with either the light_rail or tube constraints are considered low by default.
Title: Re: railway height clearance
Post by: PJMack on May 09, 2022, 10:10:34 PM
After going down several rabbit holes of articles and websites trying to get an idea of rail rolling stock and loading gauges in Britain, I have come up with a few options.

The first option is to leave things alone.

The second is to just have tube and light rail vehicles be short.  This would have the discrepancy that some mainline vehicles are actually shorter than some of the light rail vehicles.

The third option is to have the tube, light rail, and sub-surface vehicles short.  This would still have discrepancies as some of the mainline stock is shorter than sub-surface stock.  This was already vetoed in another forum thread.

The fourth option is to set a threshold (say 12'6") where all rail and light rail vehicles taller than that would be considered tall.  This would involve looking up and/or estimating the heights of all the vehicles in the pakset.

The fifth option would be to have all mainline rail vehicles and single deck trams to be short, as they are all about the same height anyway.  This would probably be the most accurate for the least amount additional research and work. 
Title: Re: railway height clearance
Post by: PJMack on May 17, 2022, 01:36:09 AM
I did find that when doing AC electrification of lines in Britain, several bridges had to be raised.  A sixth option would be to have rail vehicles with AC centenaries be tall.  (I know the clearances needed for DC overhead wires is lower than the 25kV AC wires.)

As the changes would highly effect the game balance, I would like other player's opinions on this before proceeding with any further changes to the PR. 
Title: Re: railway height clearance
Post by: Octavius on May 17, 2022, 01:53:27 PM
This reminds me of the discussion of Pluto being a planet or not. There is some distribution of objects which we have to put into two categories and we're looking for a clear gap in this distribution. Left of the gap is in one category, right of the gap is in the other. In the case of planets and dwarf planets such a gap exists (Pluto is clearly on the dwarf side of it), but in case of trains I don't see such a gap. If all trains had been either London Underground tube stock or American Superliners, it would have been easy. Those are some of the lowest and tallest trains in the world and the latter are about twice as high as the former.

British mainline stock is pretty low, compared to continental stock and even more so compared to Russian or American stock, so I think that option 5 is reasonable. Furthermore, if we require 2 levels difference for bridges over a mainline railway, what difference do we need for bridges over a navigable river? The standard for bridges over the Rhine is 9.10 metres plus the thickness of the bridge deck, about twice what's needed for mainline railways. I think the cut-off for rail vehicles should be similar to the cut-off for road or water vehicles. (For sea-going ships the limit is more or less 65 metres, about the height of the Great Belt Fixed Link and the Verrazzano-Narrows Bridge, which, IMHO, should be much more than 2 levels.)

Quote from: PJMack on May 17, 2022, 01:36:09 AMI did find that when doing AC electrification of lines in Britain, several bridges had to be raised.  A sixth option would be to have rail vehicles with AC centenaries be tall.
Then it would make more sense not to allow building AC catenary under low bridges. If DC electrification can be used under low bridges and AC can't, then a dual voltage train should be able to pass under that bridge when running on DC (with its AC pantograph lowered).

Title: Re: railway height clearance
Post by: Matthew on May 18, 2022, 03:28:50 PM
I am not yet decided about all these questions. But the related patch to make single-height ("low") bridges possible (over railways) would definitely be an improvement. It has always struck me as odd that you have to build double-height bridges above 19th-century railways in this pakset. The UK's loading gauge is famously small and getting to double height often involves much more expensive bridges/cuttings/embankments. It also encourages new players to build steep (x2) slopes on the bridges, which 19th and early 20th century road vehicles can't handle, causing unnecessary traffic jams and routing issues.

Quote from: PJMack on May 17, 2022, 01:36:09 AMI did find that when doing AC electrification of lines in Britain, several bridges had to be raised.  A sixth option would be to have rail vehicles with AC centenaries be tall.  (I know the clearances needed for DC overhead wires is lower than the 25kV AC wires.)

On the one hand, this makes overhead AC a much more expensive choice than third-rail DC. Third-rail DC is already far more popular than AC in Bridgewater-Brunel, because it's available so much earlier. I know that AC becomes more competitive when high-speed rail becomes available in the 1990s, but by that stage existing networks are usually already all third-rail DC. The underlying problem is that we don't simulate the fact that third rail is so much more dangerous. In the 2010s, Network Rail banned all new third-rail lines and intended in principle to convert the existing ones to overhead AC, at colossal cost. That policy has now been reversed, but it shows how poorly we model this aspect.

On the other hand, I like the realism of having to raise bridges for overhead AC lines. By the time AC comes along, motor vehicles can handle steep slopes so it avoids the newbie trap. It also incentivizes building entirely new infrastructure for high-speed rail lines. And it is beyond the scope of this patch (or the tunnels patch to the code) to fully balance overhead vs third-rail.

So overall I like this particular suggestion.

Quote from: Octavius on May 17, 2022, 01:53:27 PMThen it would make more sense not to allow building AC catenary under low bridges.

This is true. In particular, implementing this through is_tall also makes it more difficult to give players accurate error/warning messages until it's too late.
Title: Re: railway height clearance
Post by: Vladki on May 18, 2022, 09:12:02 PM
If I may add my few cents:

- buses, and trams are IMHO easy: double deckers are tall, single deckers are not. E.g. In Brno we have this railway viaduct https://cs.wikipedia.org/wiki/Viadukt_K%C5%99enov%C3%A1 that could be considered low: Built in 1847, total height cca 6 m, clearance 3.3 m (according to the road signs). There is tram and trolleybus track (600 V DC) underneath it, but the wires are lowered, so that the pantograph is almost fully down when passing under the bridge. Of course many modern coaches cannot pass. E.g. typical tram that can pass (Tatra KT8) is 3145 mm high (excluding pantograph)

- tube, metro, dlr, and similar underground stuff that can pass small gauge tunnels is not tall

- narrow gauge trains also not tall

- standard trains are the hardest. UIC gauges (GA/GB/GC) are 4280/4320/4650 mm high, passenger cars UIC-X/Y/Z built from 2nd half of 20th century till now are 4050/4232 mm high. This would not pass under the viaduct mentioned above. But I like the idea of allowing non electrified trains under low bridges. In czechoslovakia, there were also many bridges rebuild or just destroyed due to electrification (25 kV AC). Also many tunnels had to be rebuilt to accommodate the catenary. (Or a double track tunnel was used for single electrified track, and new one was built for the other track.) There is new motorway bridge being built over  electrified railway in east Bohemia, and the road will be 11 m above ground. That is imho definitely tall bridge.

So there are imho 2 options:
a) make all standard railway stuff tall
b) make all railway stuff not tall, and allow AC catenary only under tall bridges. But then you should also distinguish between electrified and non electrified tunnels.

IMHO a) is easier for players


- ships would deserve more levels of heights, perhaps allowing for "tower bridge" that can be passed by small boats even when closed, but has to open for bigger ships.
Title: Re: railway height clearance
Post by: Sirius on May 19, 2022, 08:52:17 PM
Quote from: Vladki on May 18, 2022, 09:12:02 PM- buses, and trams are IMHO easy: double deckers are tall, single deckers are not.
Seems overly simplified to me.
I remember my recherche on Blackpool Trams.
Single deck and double deck trams are about the same height as single deck trams got that masive pantograph tower on top.
Title: Re: railway height clearance
Post by: Vladki on May 19, 2022, 09:56:48 PM
Quote from: Sirius on May 19, 2022, 08:52:17 PMSingle deck and double deck trams are about the same height as single deck trams got that masive pantograph tower on top.
Yeah blackpool single deck trams are quite an exception. I suppose that the overhead wire is higher than usual, or that they had very small pantographs that would not reach the wire without that "tower" ?

Anyway I found two photos of the oldest (1839) viaduct in Brno. The rail track beneath the bridge was built 120 years later - 1957. https://cs.wikipedia.org/wiki/V%C3%ADde%C5%88sk%C3%BD_viadukt#/media/Soubor:Brno_-_V%C3%ADde%C5%88sk%C3%BD_viadukt,_kabelov%C3%A1_l%C3%A1vka_obr03.jpg
The clearance for road vehicles is 3.1 - 3.2 m. You can see that the rail track is laid quite a bit lower than the road, and even then I doubt it matches current UIC standards. Judging from this photo - double deck cars would be a tight fit... The cars on the photo are UIC-Y (4232 mm high). Just enough for most railway stock, but no space for 25 kV catenary. So the question is - should this be still considered a "low" bridge ?
https://mapy.cz/zakladni?x=16.6054045&y=49.1836110&z=16&pano=1&source=base&id=2103564&gallery=1&sourcep=foto&idp=4165737
Title: Re: railway height clearance
Post by: PJMack on May 19, 2022, 10:25:40 PM
I pushed changes to the code and pakset PRs to have AC electrification require full height.  I did not yet change the rail vehicles since it would require either changing the default height in code (which could mess with the balance of other paksets) or setting "is_tall=0" for 850+ vehicles in pak128.Britain-Ex.  Unless most of the other pakset designers also want the default height for rail vehicles to be short, the latter choice would have to occur which would take some time.



Quote from: Vladki on May 18, 2022, 09:12:02 PMships would deserve more levels of heights, perhaps allowing for "tower bridge" that can be passed by small boats even when closed, but has to open for bigger ships.
Creating the tower bridge in Simutrans would be a nice feature but is a little beyond the scope of this PR.  I have looked into the crossing logic before, and hypothetically having a canal cross a road the way that a rail crosses a road would only require pakset modification for a draw bridge graphics, but I have not tried it.  Having a draw bridge to go from half height to full height would involve a significant amount of coding.  Likewise, adding more levels of height clearances would be a significant undertaking given how the code is currently written.



Quote from: Sirius on May 19, 2022, 08:52:17 PMSeems overly simplified to me.
I remember my recherche on Blackpool Trams.
Single deck and double deck trams are about the same height as single deck trams got that masive pantograph tower on top.
It is somewhat oversimplified, but it is easier for the player and pakset designers to be able to determine the in game height at a glance.  As far as the Blackpool Trams, the reason that the height of the pantographs are the same is that that is the height of the existing wires.  If the wires were lower, the pantographs would either be folded down, or the tram would be made with a smaller pantograph.  Trolley Poles are also designed to work with various wire heights.
Title: Re: railway height clearance
Post by: jamespetts on May 20, 2022, 11:39:03 PM
This is an interesting discussion of a complex and subtle issue. I am not convinced by the approach of requiring AC electrification to have double height tunnels, however: in reality, the difference in clearance in tunnels and bridges is relatively subtle compared to the difference in height between, for example, a Tube train and a main line train or a single or double decker 'bus, and many existing tunnels have been converted to overhead AC electrification without entirely re-boring the tunnel (e.g. the Severn Tunnel).

I think that the only meaningful height differentials that can be communicated to the player satisfactorily are between the following categories:

(1) Tube trains/narrow gauge trains (low);
(2) standard gauge trains/single decker 'buses (normal); and
(3) double decker 'buses and trams (high).

What to do with single deck trams is a slightly difficult topic. I am aware of the tower on the single deck Blackpool trams, but they were built for a network where there were no low bridges. London had single deck trams intended to pass under low tunnels (the Kingsway underpass before it was enlarged to take double deck trams), and it would be very confusing for players for single deck trams to be treated as tall, so I would suggest putting single deck trams in the normal category.

The question then becomes: where on the low/normal/high division should the dividing line be for half height tunnels? One consideration is that most slopes in the game are half height slopes, so tunnel building generally will be much easier if half height tunnel entrances are permitted for the "normal" category above. This would also make more sense when interacting with road vehicles, since there are very few, if any, road tunnels that have the same sort of ultra-limited height of the Tube tunnels or narrow gauge rail tunnels.

I would therefore suggest that, on balance, it is better to have tunnels that can be passed by double decker 'buses and trams (i.e., anything marked with is_tall=1) requiring the full height slope, and all other tunnels allowing half height. Tube tunnels would then continue to be defined by their special way constraint and this would be unchanged.

My apologies if this involves reverting some work regarding AC electrification - but at least this will not potentially involve vast amounts of further work trying to label all AC electrified trains as is_tall=1. It also does not require any new kind of height categorisation.

One other consideration is the discussion about allowing half height bridges over railways. This is probably sensible given the UK loading gauge being closer to a single decker rather than a double decker 'bus.
Title: Re: railway height clearance
Post by: Vladki on May 21, 2022, 12:15:44 PM
If the is_tall flag would be only on the electrification and not on the vehicles, it would not be that much work on pakset level.

But of course it would be more work on the simutrans code.

If I may suggest to allow the default tallness for each road type to be defined in simuconf.tab so that other paksets may decide that some vehicles are tall by default.
Title: Re: railway height clearance
Post by: PJMack on May 21, 2022, 08:29:18 PM
I set "is_tall=0" for all track vehicles in pak128.Britain using sed



Quote from: Vladki on May 21, 2022, 12:15:44 PMIf I may suggest to allow the default tallness for each road type to be defined in simuconf.tab so that other paksets may decide that some vehicles are tall by default.

Unfortunately, setting the default tallness in simuconf.tab would not be simple due to the way the settings system is currently implemented. 



Quote from: jamespetts on May 20, 2022, 11:39:03 PMThis is an interesting discussion of a complex and subtle issue. I am not convinced by the approach of requiring AC electrification to have double height tunnels, however: in reality, the difference in clearance in tunnels and bridges is relatively subtle compared to the difference in height between, for example, a Tube train and a main line train or a single or double decker 'bus, and many existing tunnels have been converted to overhead AC electrification without entirely re-boring the tunnel (e.g. the Severn Tunnel).


Quote from: jamespetts on May 20, 2022, 11:39:03 PMI would therefore suggest that, on balance, it is better to have tunnels that can be passed by double decker 'buses and trams (i.e., anything marked with is_tall=1) requiring the full height slope, and all other tunnels allowing half height. Tube tunnels would then continue to be defined by their special way constraint and this would be unchanged.

There are plenty of small subtleties to this topic that cannot be modeled in detail, however I still think double height for AC lines would be justified.  There is a minimum clearance between the wires and the train roof in order to prevent arcing.  Likewise there is also a minium clearence between the wires and any structure near it.  Adding that up, it is roughly the difference between the heights for single or double decker buses.  For the Severn Tunnel, it is two tracks in a single bore resulting in high clearances.  It also used a rigid bar rather than a wire as a preventative measure against water infiltration. 

For non-electrified tunnels, tunnels for steam trains would have needed to be tall enough not to fill with too much smoke.  The Metropolitain steam engines had condensing boilers to keep smoke down in the shorter cut and cover tunnels (the original plan was to have fireless steam engines).  I believe it best to leave the earlier rail tunnels at full height until the advent of cut and cover tunnels.

Quote from: jamespetts on May 20, 2022, 11:39:03 PMMy apologies if this involves reverting some work regarding AC electrification - but at least this will not potentially involve vast amounts of further work trying to label all AC electrified trains as is_tall=1. It also does not require any new kind of height categorisation.
Even if this feature is not used in pak128.Britain-Ex, other pakset developers may want to be able to restrict some types of electrification to full height.  Simply removing the "is_tall=1" flag in the AC electrification dat file would remove this feature for pak128.Britain-Ex.  I do think that leaving this feature in would be advantageous though.  It was requested be three others.
Title: Re: railway height clearance
Post by: jamespetts on May 22, 2022, 12:57:35 AM
Thank you for your work on this. I have spent some time this evening testing this.


First of all, I notice that there appears to be a problem with the light rail tunnel way constraint in that vehicles without this constraint pass through the tunnel without hindrance, albeit this is reproducible on the master branch. This problem is not present for the Tube tunnel constraint, so it is not a general constraint problem.


Secondly, I have tested the tunnel length restriction system, and this now appears to work well – thank you for this.


Thirdly, as to tunnel height and electrification, this is complex. The position seems to be that (1) most main line tunnels in the UK were double bore tunnels; and (2) double bore tunnels were high enough for overhead electrification to be retrofitted without re-boring. This explains why all of the tunnels on the East Coast Main Line from London to Edinburgh, the West Coast Main Line from London to Glasgow and the Great Western/South Wales Main Line from London to Cardiff have all been electrified with overhead wires without re-boring any of the tunnels along the route. By contrast, the Woodhead Tunnels (https://en.wikipedia.org/wiki/Woodhead_Tunnel), which were originally a pair of single bore tunnels, had to be replaced with entirely new tunnels when the line was electrified with overhead DC. Similarly, when in 1976 the Great Northern and City Railway was connected to the main line and through trains run from Stevenage/Hertford to Moorgate, special dual voltage trains had to be used that would run on third rail in the single bore tunnels and overhead AC electrification at 25kV outside the tunnels, changing over at Drayton Park. There is no evidence that steam locomotives needed extra height clearance because of the smoke: the narrow Woodhead tunnels were routinely used by steam locomotives.


In fact, Simutrans has a double bore tunnel feature, albeit Pak128.Britain has never used it. This feature, however, is cosmetic and only applies to the tunnel portals, rather than to the tunnel internal images. Quite how to address all of this is highly complex. Adding full dual bore tunnel support, even in a minimal way by detecting when a tunnel is being built next to another tunnel and adjusting the graphics of the internals, the cost and the height restriction accordingly (using the existing feature for the tunnel mouths) would be a substantial amount of work, as would producing graphics for double bore tunnel entrances.


Fourthly, and leading on from the above, the current arrangement in the tunnel-improvements branch of the pakset is anomalous. Tunnels can be built into shallow slopes if they are Tube tunnels, light rail tunnels or "subsurface" tunnels. The "subsurface" tunnels have the light rail constraint, but this does not work. When it does work, it only applies to single deck trams and Docklands Light Railway trains (and possibly also Tyne & Wear metro trains if they are in the pakset). The "subsurface" tunnels are intended to represent cut and cover tunnels but can in fact be built underneath established buildings without disrupting them. I think that we need considerably more consistency.


Realistically, we need either (1) to implement the double bore feature, and have double bore tunnels marked as is_tall and single bore tunnels not; (2) to retain a single bore only pakset, but have some single bore tunnels as high as double bore tunnels or higher, such as the Shakespeare tunnels:


(https://live.staticflickr.com/2694/5821847070_d89a3cae60_h.jpg)kent - 4cep 7166 leaving shakespeare tunnel dover JL (https://flic.kr/p/9SsuiC) by John Law (https://www.flickr.com/photos/johnmightycat/), on Flickr


(3) treat all rail tunnels as not being is_tall apart perhaps from some specialist double decker tram tunnels; or (4) have only light rail and Tube tunnels as half height compatible, which avoids the whole issue of the is_tall flag on railway vehicles entirely as those already have their own constraints. If we choose (2), we have to have cogent, historically accurate and economically coherent reasons that players might want to build these taller tunnels over a century before the availability of overhead electrification if they are to be more expensive than shorter tunnels.


I do not think that we can sensibly retain a category of "subsurface tunnel" with the current feature-set – it is not clear what need that this fulfils. Unless we can more accurately simulate actual cut and cover construction (including disruption of the surface during construction), then I do not think that this tunnel makes sense; it is likely to be extremely confusing to players to be able to build a "cut and cover" tunnel without disrupting the surface in any way, and "subsurface" as a description of a tunnel other than a cut and cover tunnel does not really make much sense other than to describe a tunnel that does not happen to be very deep. The best way of simulating cut and cover in the game would actually be to allow players to place artificial ground (with tunnel portals below it) on top of ways in cuttings on which other ways or buildings may be placed, including ways and buildings built automatically by cities, but there would need to be a more sophisticated economic basis for this (such as players being able to sell or lease the land atop their lines) or else players would never expend the money to do this. I should note that the cut down tunnel portal graphics that you have produced for this are likely to be useful for the light rail tunnel, so will not go to waste.


In terms of the is_tall flag, I do not think that it makes sense to have this set to 1 automatically for all rail vehicles but not for other types of vehicles, so I have reverted this. As set out above, it may be that is_tall is usable for all overhead electrification types in conjunction with some double bore system or some other genuine reason, not currently clear, that players might want to build extra tall single bore tunnels.


In any event, in summary: the coding work seems to be very helpful, save that we have possibly discovered a pre-existing bug relating to the light rail tunnel way constraint; whether this is a bug of pakset or code is currently unclear. However, the pakset still needs further consideration to remove the anomalies that exist at present. I agree that we should definitely retain the ability to have is_tall set for a specific way constraint in case any pakset author finds this helpful even if we decide not to add this to Pak128.Britian-Ex.
Title: Re: railway height clearance
Post by: Vladki on May 22, 2022, 06:10:57 PM
Just one note, about double bore tunnels and their height. The situation might be different in different countries. In Czechoslovakia even double bore tunnels had to be rebored, to accommodate electrification. Or in some cases the old double bore tunnel was used for only one track (the clearance in the middle was enough) and new tunnel for the other track was bored nearby. https://commons.wikimedia.org/wiki/File:Novohradsky_tunel_(c._8)_-_jih.jpg#mw-jump-to-license
Title: Re: railway height clearance
Post by: Octavius on May 23, 2022, 07:54:28 PM
Quote from: Vladki on May 18, 2022, 09:12:02 PMnarrow gauge trains also not tall
Narrow gauge trains are a very diverse category. On one extreme there was the Isle of Mull Railway (260mm gauge), little more than a toy train and the smallest train I ever travelled in, but there are also the much larger trains of the Rhätische Bahn (1000mm). Technically, the giant Garratts of the South African Railways are narrow gauge too (1067mm), but if anybody ever builds a South African pakset, I expect those will be put in standard gauge, reserving narrow gauge for the 610mm stock. So, some may be high, some may be low, depending on what cut-off you use. The British narrow gauge trains all appear quite small.

(https://upload.wikimedia.org/wikipedia/commons/thumb/c/cc/LOTI_at_Torosay_station_on_the_Isle_of_Mull_Railway.JPG/320px-LOTI_at_Torosay_station_on_the_Isle_of_Mull_Railway.JPG) (https://upload.wikimedia.org/wikipedia/commons/thumb/2/25/Durstig%21_RhB_G_3-4_Nr._107.jpg/320px-Durstig%21_RhB_G_3-4_Nr._107.jpg)
(https://upload.wikimedia.org/wikipedia/commons/thumb/8/87/Class_GO_2575_30th_May_2005_%287864141540%29.jpg/320px-Class_GO_2575_30th_May_2005_%287864141540%29.jpg) (https://upload.wikimedia.org/wikipedia/commons/thumb/e/e2/SAR_Class_NG_G16_113_%282-6-2%2B2-6-2%29.JPG/320px-SAR_Class_NG_G16_113_%282-6-2%2B2-6-2%29.JPG)
These four locos are all narrow gauge. All from Wikimedia commons: 1 (https://commons.wikimedia.org/wiki/File:LOTI_at_Torosay_station_on_the_Isle_of_Mull_Railway.JPG), 2 (https://commons.wikimedia.org/wiki/File:Durstig!_RhB_G_3-4_Nr._107.jpg), 3 (https://commons.wikimedia.org/wiki/File:Class_GO_2575_30th_May_2005_(7864141540).jpg), 4 (https://en.wikipedia.org/wiki/File:SAR_Class_NG_G16_113_(2-6-2%2B2-6-2).JPG). That last series is actually used in Britain, on the Welsh Highland Railway. The first was used in Scotland.

Quote from: Sirius on May 19, 2022, 08:52:17 PMSingle deck and double deck trams are about the same height as single deck trams got that masive pantograph tower on top.
After watching some images, it looks like they just wanted to use the same type of pantograph on all trams, just to limit the number of spare parts. The entire network was designed for doubledeckers anyway. On tram networks without doubledeckers (i.e., most outside of the British Empire), they use very tall pantographs that can still fold almost to roof level. On streets shared with lorries and the occasional doubledecker bus, the wires must be high, but sometimes you want to run the tramline under a low viaduct where those lorries can't pass. Low wires are also used in tram tunnels or wherever the tram has its own right-of-way. I don't think anyone would use such tall single deck trams if that would cause limitations for where it could go.

Quote from: jamespetts on May 22, 2022, 12:57:35 AMapart perhaps from some specialist double decker tram tunnels
Do we have any real-world examples of doubledecker tram tunnels? I expect anyone who wanted to use tram tunnels would use single deck trams. The trams would be a bit longer, but that should be no problem for trams

Quote from: Vladki on May 22, 2022, 06:10:57 PMOr in some cases the old double bore tunnel was used for only one track (the clearance in the middle was enough)
The same in Belgium for the line from Liège to Luxembourg, which is electrified on the Luxembourgish 25kV AC system (not the Belgian 3kV DC system). They reduced the entire line to single track though, as traffic has become rather light.
Title: Re: railway height clearance
Post by: jamespetts on May 24, 2022, 11:06:34 AM
QuoteDo we have any real-world examples of doubledecker tram tunnels? I expect anyone who wanted to use tram tunnels would use single deck trams. The trams would be a bit longer, but that should be no problem for trams

Yes - the Kingsway tunnel in Holborn, London was rebuilt, I think in the 1930s, to accommodate double deck trams. The remains of it can still be seen to this day. There are several Youtube videos showing it being explored.
Title: Re: railway height clearance
Post by: PJMack on May 24, 2022, 10:25:09 PM
Quote from: jamespetts on May 22, 2022, 12:57:35 AMThirdly, as to tunnel height and electrification, this is complex. The position seems to be that (1) most main line tunnels in the UK were double bore tunnels; and (2) double bore tunnels were high enough for overhead electrification to be retrofitted without re-boring. This explains why all of the tunnels on the East Coast Main Line from London to Edinburgh, the West Coast Main Line from London to Glasgow and the Great Western/South Wales Main Line from London to Cardiff have all been electrified with overhead wires without re-boring any of the tunnels along the route. By contrast, the Woodhead Tunnels, which were originally a pair of single bore tunnels, had to be replaced with entirely new tunnels when the line was electrified with overhead DC. Similarly, when in 1976 the Great Northern and City Railway was connected to the main line and through trains run from Stevenage/Hertford to Moorgate, special dual voltage trains had to be used that would run on third rail in the single bore tunnels and overhead AC electrification at 25kV outside the tunnels, changing over at Drayton Park. There is no evidence that steam locomotives needed extra height clearance because of the smoke: the narrow Woodhead tunnels were routinely used by steam locomotives

The Woodhead tunnels are an interesting case.  I did notice that the article described the tunnel as being too narrow rather than too short and am wondering why that is the case.  Following the sources reveiled more questions than answers, as one of the sources described the original tunnel being 6.1m tall (~20ft) and 4.5m wide.  Given that loading gauges in Britain describe maximum mainline heights from around 12-14 ft (13ft for W6A), one must question the reason for the extra ~6ft of headroom.  One explanation would be for smoke (where in that case, it was not enough) however the other could the extra space being a side effect of geometry and construction techniques.  As the bore needs to be arch shaped, and the arch height needs to be at least half the width or more depending materials, it is possible that that is the height needed for the tunnel to be the proper width at 13ft above track bed and still be structurally sound.  In any case, 6.1m would be too tall for half height in the pak128.Britain-Ex graphics scale.

Quote from: jamespetts on May 22, 2022, 12:57:35 AMThe "subsurface" tunnels are intended to represent cut and cover tunnels but can in fact be built underneath established buildings without disrupting them. I think that we need considerably more consistency.
The early subsurface tunnels prohibit building below buildings whereas the later tunnels permit it with a large surcharge.  Is this feature not working?  There is an exception where a non-road tunnel parallel to the same tunnel type beneath a road is not considered to be under the building (The idea being that two tracks can fit under a road).  As discussed in another thread, building a cut and cover tunnel beneath an existing building is possible, though expensive, so the in game price is set to between the costs of small buildings (which in reality would be cheaper to tear down) and large buildings (which in reality would be cheaper run the tracks through the basement).  There is also a surcharge for building beneath existing ways to represent all of the temporary structures needed to keep access to buildings along the road during construction as well as rebuilding the road.  In reality, cut and cover tunnels can be built without closing the entire road but leaving the sidewalks and maybe a few lanes open.  This would be difficult to emulate in Simutrans and contradict the "instant construction" philosophy for building ways; temporary road closures and detours are also required for repaving and building crossings or tram tracks.

Quote from: jamespetts on May 22, 2022, 12:57:35 AMIn terms of the is_tall flag, I do not think that it makes sense to have this set to 1 automatically for all rail vehicles but not for other types of vehicles, so I have reverted this.
This may not make sense for the British pakset, however in North America and somewhat in Mainland Europe, rail vehicles tend to be much taller.  Setting is_tall for rail vehicles be default means that other paksets would also behave as they did.  I did not want to inadvertently mess with the balance of the other paksets.
Title: Re: railway height clearance
Post by: Matthew on June 03, 2022, 06:07:47 AM
What was decision has been implemented for mainline rail vehicles in this pakset, please? Are they currently suitable for cut-and-cover tunnels or not? I am guessing not, but there is no indication either way on either historical mainline or tube vehicles.
Title: Re: railway height clearance
Post by: jamespetts on June 03, 2022, 11:23:49 AM
Rail vehicles are not marked as is_tall by default. Thus, ordinary rail vehicles can use cut and cover tunnels.
Title: Re: railway height clearance
Post by: Matthew on June 04, 2022, 05:03:54 AM
Quote from: jamespetts on June 03, 2022, 11:23:49 AMRail vehicles are not marked as is_tall by default. Thus, ordinary rail vehicles can use cut and cover tunnels.

Thank you! Tunnel construction will commence.