DLR P86 coupling constraints

[Mariculous]

Hey there,
The DLR P86 just became available.
However, these can't be coupled, which makes them pretty useless for me. In reality at least 3 of these can be coupled. I often see them in Essen, so I really want to use them
https://upload.wikimedia.org/wikipedia/commons/7/72/EVAG_P86_5211_Hauptbahnhof.jpg

I guess the missing coupling is a bug. I could not find any source mentioning that these could not be coupled and the DLR rolling stock mentions that any rolling stock is coupled from 2, 3 or later even 4 trains.

[Spenk009]

In the dat file, they are explicitly limited to only run in pairs. This is deliberate. I don't know whether there are any technical factors limiting joint operation, so all I can do is come up with some images, that might prove it was done. There are no P89 in the game, with them being almost identical to the P86, so features may be different.


from here This is tagged as p86 (probably p89), but taken in 1993 and it clearly shows two sets together.


Another image captioned: "DLR P86 stock at Canary Wharf" from here

[Rollmaterial]

Another image captioned: "DLR P86 stock at Canary Wharf" from here

This isn't a P86. The emergency end doors and the sliding doors clearly indicate it is a B90 or one of the follower models.

[Mariculous]

Indeed, the second image isn't a P86.
The first is #12 of the P series, so it's the first P89.
In Essen both, P86 and P89 definitely operate in joint operation of up to 3 trains/6cars but that's not a reliable source for the DLR as the EVAG overhauled these trains. Even P86 can be joint to P89 after that overhaul.

I could not find any image or information of two DLR P86 being joint.
However, I could also not find any source stating it was not possible and it is imho very unlikely that the P86 could not use its Scharfenberg Coupling to couple to another P86, whereas the P89, which is basically the same train with fire fire-proofing equipment.

So I would suggest allowing the P86 to be joint with another P86 unless we find any relyable source that states it was not technically possible or there are any other good reasons not to do so.

[jamespetts]

My apologies for not having replied to this earlier: I had missed some of the discussions in this subforum until the last few days.

The P86 were in reality limited to individual pairs and could not be coupled together. This is one reason that their use was discontinued early compared to the other Docklands Light Railway trains.

[Mariculous]

I did not find any sources about this, could you please share your source, I would really much like to read about this as it sounds quite stupid to me equipping trains with Scharfenberg couplers when they can't use it.

However, if it really was technically not possible, we should introduce P89 when it was introduced, which Spenks image proves to be operated coupled together.

[jamespetts]

I did not find any sources about this, could you please share your source, I would really much like to read about this as it sounds quite stupid to me equipping trains with Scharfenberg couplers when they can't use it.

However, if it really was technically not possible, we should introduce P89 when it was introduced, which Spenks image proves to be operated coupled together.

Looking at this again, I cannot seem to find the source for this; and I note that they did have couplers on the front. I have allowed them to be coupled to other P86 units, but not to others, as I believe that these were not compatible with later units.

[Mariculous]

I guess they were compatible to P89 before the Essen rework already, but as we don't have P89 ingame for obvious reasons that doesn't matter.
I don't think they were compatible to any other DLR stock either.

However, allowing P86 to couple to another P86 will make them much more useful

[Vladki]

Now they cannot be built at all. The constraint none should have been preserved. The current contrains allow only inifinitely log chain of P86 coupled together

[jamespetts]

Thank you for that report: now fixed.

[Mariculous]

Well now they can be used again but can't be coupled to another P86 :/
I guess you need both constraints, none and P86.

[Vladki]

The problem with constraint is that rear has to be constrained to front on both sides, and vice versa.
Look at the constrainsts for tyne&wear class 994. It should be similar

[jamespetts]

I have merged Freahk's fix for this - thank you for that.