zbang
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Post by zbang on Mar 16, 2023 0:30:22 GMT
The issue with barcodes is that they take noticeably longer to read at the barrier. Do they? Which codes and which reader/barrier?
A lot depends on the reader- the systems used by parcel companies and airports are rather spritely, and even 2d codes should read at 20+ per second even in motion. Perhaps the issue isn't that they're barcodes but the specifics of the setup.
A 500ms read time would be in the same range as reading a chip and an acceptable speed for the user. (I find many chip readers are too slow; in the 2-3 second range at times.)
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zbang
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Post by zbang on Mar 14, 2023 19:38:20 GMT
With Oyster, you don't benefit from the weekly cap. There's no excuse for this. It's just a matter of post-processing the data that they have (and indeed, send you, if you have an Oyster card account). AFAICT PAYG Oyster does cap fares at daily/weekly/monthly- that's well-marketed and it would quite surprising if it didn't work. Wouldn't take much for someone to do a controlled experiment and see- simply make four zone 1-2 journeys in a day with an Oystercard and see how much is spent (4 * £2.70=£10.80 or £8.10 for one-day anytime TC).
With CC/DC, you can't add railcards. Again, there is no reasonable excuse for this. If they can instantly access databases to validate CC/DD/Phone payments, why can't they have a server to interrogate to determine if a particular card is linked to a railcard? (using "touch-card" and "contactless" as synonyms)
As I understand the processing, the Oyster and touch-card (credit/debit/device) data flows are completely different. That is, once the reader and controller determines that the read is from an Oyster, the data goes (and comes) from the Oyster processing back-end. With the touch-card, there is no data going back into the card so pretty much all that's needed at the gate is knowing if the card is valid; everything else happens at end-of-day processing*. Linking a server-stored railcard with the touch-card processing would require some non-trivial database connections and have non-trivial privacy implications.
(AFAIK one company (Cubic?) operates the Oyster back-end and another operates the touch-card back-end.)
*TfL takes the risk of a card being invalidated during the day or being over its limit; I expect that this was well-analysed and the cost of letting a few go through unpaid is much less than the cost of processing the transactions at the end of each journey. This gets into the weeds of card processing.
From a two year old article (https://www.mobility-payments.com/2021/09/29/in-depth-contactless-transactions-soar-but-transport-for-london-affirms-that-oyster-will-remain-a-payments-option/)
When that happens, I'd say linking railcards to contactless becomes much more possible. No idea how the project is going, haven't bothered to look.
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zbang
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Post by zbang on Mar 13, 2023 20:48:56 GMT
Smell of electrical burning is more often than not insulation. You only need some plastic like a carrier bag lodged in the wrong place and melt and burn and hence the smell. IME, the first thing you'll smell is burning dust and other collected detritus; it starts to smell long before the motor insulation does.
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zbang
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Post by zbang on Mar 13, 2023 0:59:15 GMT
Happened 20 years ago, is it still a problem? And how that that generally affect the TC vs PAYG question? (In general, I don't think it does.)
According to the current OSI spreadsheet, the only Bank/Bank OSI is between "Central/Northern/DLR and Waterloo & City gatelines", so Gants Hill (Central) -> Bank (Central) & Bank (Central) (interchange somewhere) Uxbridge (Met) wouldn't seem to qualify. Of course, this could well have been different 20 years ago. Out Bank / in Cannon St would also qualify, the other OSIs from Bank are into NR stations.
There are many OSIs that are explicitly PAYG only and a few that are contactless only.
Either way, ducking out of a station to transact some business seems a bit abusive of the allowed interchange period; great if it works but not much to grouse about if it doesn't. IMHO and all that.
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zbang
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Post by zbang on Mar 12, 2023 6:30:13 GMT
We have two separate parts, a "loophole" journey and a privacy concern.
First, it's been eight months I was last in London, but I used my touch card all the time and from the card statements it was obvious that fares were being capped, both daily and weekly. IIRC when I checked, it was at or below the travelcard rate. (That's why I didn't bother getting a travelcard.) OTOH I was probably never outside zone 4. Using the TfL travelcard calculator, a zone 1-4 daily card is £15.20 whilst the PAYG cap is £11.70 (zone 1-2 daily cap is £8.10). Not sure how that is a charade.
You may have found a particular case where the system didn't behave as desired; that doesn't change the maths above. You also may have hit an oddity at Bank- I don't recall if there are parts of the station which aren't connected inside the fare gates*, and exiting/reentering the station seemed like a normal interchange. If you had reentered the system at another station, it probably would have worked as desired (two separate journeys).
*I know there are some where you exit one gate, walk maybe 10m, and enter another of the same station.
I still don't see how for the majority of people that a travelcard is better than PAYG with fare capping.
If one is interested in the least amount of personal tracking, then yes, cash fares are a good way to do that, but why use a travelcard then as the one card will appear for multiple journeys? Would be better to pay a single journey fare each time.
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zbang
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Post by zbang on Mar 11, 2023 18:07:04 GMT
I am hoping that this will help ensure the future of one day Travelcards, which are more flexible and passenger friendly than PAYG (pay as you go) as there will not be a need for journey time limits - you pay upfront and as long as you stay within the zones that you paid for you should never end up with a maximum fares charge leaving you stranded somewhere (spoken from bitter experience) nor have any other need to pay extra. I though Travelcards were being discouraged because with PAYG fare capping they become (mostly) redundant-
"If you make several rail journeys, or a mixture of rail, bus and tram journeys in one day, daily capping is better value than buying a Day Travelcard in Zones 1-9."
Since the Travelcard value sets the cap, TCs would seem of limited use to most people; I've personally found that the case, but it's a sample of one. (As the cap week is Mon-Sun, there may be a few benefits of a TC to the person whose weekend is not Sat/Sun.)
Either way, replacing a mag stripe with a 2d barcode (which can contain a ton of info) makes a lot of sense.
There's also a tangent discussion of stored-value cards (e.g. Oyster touch or mag-stripe) vs centrally-validated cards (credit/debit touch or optically-read); that would deserve another thread.
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Post by zbang on Mar 10, 2023 17:27:08 GMT
Lots of transit agencies are dropping paper but they run headlong into the problems that not everyone has or will use a mobile phone app, not everyone has a credit/debit touch card, and not everyone can pay the fee for a transit card (now £7(!) for an Oyster). They make it difficult to just walk up and pay the fare in cash.
IIRC a few cities in the US have programs to waive the card fee for low-income riders and discount the fares, TfL would need something like that, too.
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Post by zbang on Mar 7, 2023 18:35:54 GMT
6)Northern line drivers would rightly revolt and commence industrial action in response to being asked to transfer from 95TS to the far less safe and less ergonomic 73TS cabs. Please expand on "far less safe".
(I'm not sure that "less ergonomic" is a good basis for action, but I'm not a LU driver. I do know that in many places a driver is expected to operate a variety of locomotives with different controls.)
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Post by zbang on Mar 2, 2023 16:55:34 GMT
"The operator of the lift in a department store was tired of being asked the time, so he installed a clock. People stopped asking the time and instead asked 'Is that clock right'?"
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Post by zbang on Feb 27, 2023 1:31:23 GMT
FWIW, an example in the Cambridge Dictionary is "Cooking time required: 30–35 mins." whereas Oxford says "Cook for 8–10 min. until tender."
In this case, it's a matter of style and the reader's comprehension, not exact correctness.
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Post by zbang on Feb 26, 2023 21:27:57 GMT
Beauty is in the eye of the beholder? Various sources say that the correct abbreviation of "minutes" is "mins". Since the DMI isn't exactly showing a scientific measurement and it's really common to say "five minuteS", having the s when the time isn't one is more correct (that's standard pluralization(. What gets me is the laziness of some programmers to not recognize when the quantity is one and remove the "s"; even in a micro-controller this isn't difficult. (That said, I consider this on par with arguing whether to not to add milk to tea ; strong feelings either way and few will shift their opinions.)
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zbang
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Post by zbang on Feb 24, 2023 23:03:18 GMT
But are you sure about what I do in my day job ? Don't know much about that, but I do know what I do at mine; keeping old systems alive has been part of it for a fair while.
Perhaps better to leave it as different but still valid experiences.
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Post by zbang on Feb 24, 2023 22:09:54 GMT
Also, don't forget there is a progressive drift of COTS equipment through obsolesence. COTS electronics kit these days rarely has a OEM production life of more than 1-2 years, and new stock shelf life more than 5 years until depleted. Not so sure about that. COTS in this case is a funny thing- the market for DMI-like devices is rather small, so it's in the maker's best interest to build and support something that lasts; 'course not all of them do and they fall by the wayside. Or a new technology pops up and with nobody buying the old they stop making it.
Many Single Board Computer (SBC) vendors advertize 5-10 years of availability; I'm thinking of the Arduino/ESP32/PIC based systems (which could readily run a DMI and make tea at the same time) and the x86 industrial market systems. The realm of of industrial computing is vastly different from the home/commercial world.
FWIW, Daktronics (US) was founded in 1968 and is still around making scoreboards and display panels.
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zbang
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Post by zbang on Feb 22, 2023 16:33:48 GMT
Largest or most important, at the time, in the eyes of the directors. [...] Which is precisely why this subject is an endless debate. There is no perfect logic or 100.000% water tight system anyway; when you add directors whims you have no chance to rationalise it. At least as endless debates go, it can be interesting and amusing. And a "convention" is only a usual way of doing things, not The Iron Fist of Policy, I expect there would be a lot of name changes over time if that was true.
(This is similar in the IT world to corporate username policies, in <many> years involvement I've never seen one that didn't eventually break, and often on an important person.)
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Post by zbang on Feb 15, 2023 15:51:51 GMT
Unless you incline towards the Imp of the Perverse, it might be a good convention to avoid station names that aren't immediately pronounceable on a phonetic basis. Like Woolwich ?
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Post by zbang on Feb 14, 2023 7:02:57 GMT
Largest or most important, at the time, in the eyes of the directors. Makes me wonder what the tie-breakers might have been for things like branches between to main lines. A coin toss may have been involved.
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Post by zbang on Feb 13, 2023 22:43:04 GMT
For completeness, I'll mention the madness of railway timetable directions, which occasionally come close to the compass direction, and the use of Up/Down where London isn't involved e.g. Liverpool-Hull (there may be a method/convention, I'm just not aware of it).
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Post by zbang on Feb 11, 2023 17:44:26 GMT
Air pressure and humidity, however compared to the mass of the tunnel and earth it probably hardly makes a difference.
Also just a theory.
Throwing out wacky ideas- any correlation with the tides and ground water level?
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zbang
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Post by zbang on Feb 6, 2023 5:35:00 GMT
This sounds more like a printing issue than one with the PDF.
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Post by zbang on Jan 30, 2023 21:10:21 GMT
I've zoooomed in on the standard map and at 1600% it still looks good on the screen using a PDF viewer, didn't look so good using the viewer in Firefox browser. Some viewers are not good at scaling for large print, and many print drivers aren't good at rasterizing a large image for printing as multiple pages (tiles).
(The metadata says it was produce by Adobe Illustrator (MAC) and contains embedded fonts, so those should scale well.)
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Post by zbang on Jan 20, 2023 19:17:12 GMT
Couple of questions- If a train is reversing, as different from stabling, it's going to leave that siding within a fairly short period. Yes? (the risk is a disruptive passenger, not an abandoned one)
If a train is to be reversed, are station staff always on-hand to tip out the train? What when they're not available?
Like many things, it seems like there are subtleties that aren't brought forward.
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-3°C
Dec 13, 2022 17:54:05 GMT
Post by zbang on Dec 13, 2022 17:54:05 GMT
Covers keep the 3rd rail clear and heaters keep the points clear, but they still have to plow the tracks when the snow gets high enough.
Where used, I also expect that the train stops would need to be cleared and checked. (How much icing can they tolerate and still move properly?)
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Post by zbang on Dec 12, 2022 23:30:17 GMT
Some, such as the Washington DC Metro, have covers over the third-rail; others, like the Chicago "L", mount scrapers ahead of the contact shoe.
OTOH if an area seldom gets snow/sleet/freezing rain, there isn't much reason to maintain these sorts of things- TfL wouldn't have RATs (rail adhesion trains) if it wasn't an annual problem.
Somewhat related- Lines using overhead pickup (and with two pantographs per unit) will often run with both pan's up but the first disconnected; that one breaks any ice off the wire while the second picks up the power as usual.
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Post by zbang on Dec 9, 2022 18:38:07 GMT
I hope that it's not really 802.11 wireless networking (commonly known as WiFi) but rather a purpose-built radio system on different frequencies. (Might look this up later, but we're a long way from track circuits at this point.)
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zbang
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Post by zbang on Dec 8, 2022 16:58:35 GMT
Dstock7080 cited the rules for RFID tags on the subsurface version of Seltrac. The Northern and Jubilee versions of Seltrac don't use RFID tags at all. I therefore apologise for any misinformation and confusion on my part, as zbang had referred to the generic CBTC name rather than the separate CBTC/TBTC differentiation as used by LU.
I was somewhat ignorantly thinking in the context of the TfL lines which use any form of TC which doesn't involve track circuits/axle counters/etc and hand-waving around any system differences.
After that, it seems that another point is being ignored- it appears all the systems use some form of fixed monument to determine & correct the assumed train position and that these monuments are fairly close together. It doesn't matter, conceptually, whether that monument is an RFID tag, an induction loop, some kind of active transponder, a barcode, or what; they all use a the spot on the ground that says "You are here".
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zbang
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Post by zbang on Dec 8, 2022 3:43:09 GMT
Thanks, much closer than I had expected.
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Post by zbang on Dec 7, 2022 19:04:13 GMT
Which leads to- What's the rationale for placing the transponders? I'd assume that one or two per station, maybe another in longer sections between stations. More? That gets into how accurate the dead-reckoning* is between the known points; I'd assume that with almost constant error correction, it ought to be pretty good.
*using the nautical meaning since I don't think there's an equivalent term in railway use
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Post by zbang on Dec 6, 2022 17:19:57 GMT
Without axle counters, track circuits, etc, how does CBTC determine the train position? Is there something like fixed transponders or optical targets with dead-reckoning between those monuments?
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Post by zbang on Nov 24, 2022 3:54:33 GMT
Demolition of a derelict, railway-locked electricity substation in danger of collapse Any other info on that? The network rail web page doesn't elaborate.
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Post by zbang on Nov 21, 2022 16:31:49 GMT
I do approve of single but longer closure 'hits' rather than endless weekend closures, however (from the way I understand what is being said) the fact that the works were so frequently deferred until we reached what sounds like 'emergency closures before something bad happens' does not fill me with confidence in how our railways are managed. Something similar also recently occurred on the Boston Mass. USA Orange line, I am shocked to now find what sounds like a similar-ish scenario taking place here in London.
As I understand, the Orange line closure has generally been considered successful and allowed the MBTA to get far more work done than they would have with a succession of weekend closures ("Thirty days of 24-hour access to the Orange Line replaces over five years of weekend diversions needed to address delays and slow zones.")
Oh, in this discussion, are AC and DC lines referring to the traction power or something else?
(Massachusetts Bay Transpo. Authority)
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