|
Post by 100andthirty on Jan 31, 2022 9:58:46 GMT
I Travelled southbound from Euston to Victoria on 29th January 2022. This was the first time in a while. There were reasonable spaces between trains so there was no reason for any signal checks. However the entry into Euston from Kings Cross was much slower than usual. Also on the run out from Green Park towards Victoria, the train accelerated and then braked and travelled at a much lower speed than usual. I know that the route from Kings Cross to Euston is prone to corrugation and I suspect the Green Park to Victoria section is also affected. Could these slower speeds be in place to manage noise levels?
|
|
|
Post by 100andthirty on Jan 25, 2022 20:37:28 GMT
I wouldn't be surprised that some of this is a leftover from TfL's "have its cake and eat it" desire for a manually driven train suitable for driverless operation with the cab partition removed. That said, it's good this has been discovered now compared with discovering after the trains have been built as has been seen on one or two of the TOCs
|
|
|
Post by 100andthirty on Jan 25, 2022 20:32:54 GMT
I cannot understand why its so slow now, even for trains which are running late. Myself and my District line colleagues are still waiting to see any evidence of this notion that CBTC can make up lost time (up to 10% is the claim). On the other hand, NB met trains departing Finchley road are still doing so under manual driving and to this day, cannot match the acceleration of the jubilee line trains next to them. S stock performance on the legacy railway is definitely capped compared to when its on the CBTC railway. The difference when we depart the boundary at Sloane Square or Stepney Green is immediately noticeable. On the parts of the sub-surface railway with the old signalling, the train performance was capped to that of the old trains. This was also true on Central, Jubilee and Northern lines prior to the signalling upgrades. The reason is that on LU, signalling design and train performance go hand in hand*. The only exception that I recall is the 2009 stock on the Victoria line where the new trains were introduced with their full performance whilst the old trains remained**. That was allowed because the new ATP/ATO on the new trains took account of the higher performance, whilst the old trains continued at their somewhat more pedestrian pace. * a short answer with more complexity than I can go into here ** another short answer with an even more complex long version!
|
|
|
Post by 100andthirty on Jan 13, 2022 16:13:28 GMT
norbitonflyer.....1972 mkII was designed for the Fleet line. It was fitted with wiring for ATO which came in handy for various subsequent projects that needed some spare wires.
|
|
|
Post by 100andthirty on Dec 20, 2021 11:19:53 GMT
If I'm reading the photos correctly, I think the detrainment device is build into the cab front door similar to the Jubilee line.
|
|
|
Post by 100andthirty on Dec 19, 2021 9:06:24 GMT
Building on dm1's comment, although one VVVF inverter may feed several asynchronous motors - four per inverter on LU - it is usual for each permanent magnet synchronous motor to have its own inverter.
|
|
|
Post by 100andthirty on Dec 17, 2021 18:20:06 GMT
A tiny note about the above; As far as I recall none of the LU 1986TS trains had AC traction motors. Yes, all three were DC choppers.
|
|
|
Post by 100andthirty on Dec 16, 2021 20:42:53 GMT
You can't feed an AC supply direct to AC motors unless you want them to run at a constant speed (rpm = supply frequency x number of poles in the motor/2, I think).This is fine for driving a clock but obviously not very practical for railway use. So you convert to DC and then either use a DC motor or generate a variable frequency signal from the DC. At least two of the three-phase AC systems, both in Switzerland - both rack and pinion mountain railways - did indeed feed AC more or less directly to AC synchronous motors whose speed is locked to the frequency. This was in the days before there were any electronics! The Jungfrau railway train had a two speed gearbox with a higher torque/lower speed ratio for the steeper sections of the line. <<rincew1nd: quote attribution fixed>>
|
|
|
Post by 100andthirty on Dec 16, 2021 15:02:35 GMT
The few three phase AC railways generally use two overhead conductors and the track to supply the three phases. The thing about modern AC traction drives is that the supply has a fixed frequency (DC = 0 Hz) but the asynchronous motors don't respond well to a fixed frequency. The inverters are know as variable voltage, variable frequency systems, delivering gradually increasing frequency and voltage as speed increases. This isn't the place to go into the technical aspects, but Googling Variable voltage, variable frequency motor drives offers articles such as this: electricalbaba.com/vvvf-speed-control-of-induction-motor/
|
|
|
Post by 100andthirty on Dec 1, 2021 14:02:20 GMT
My thought was this; the Elizabeth Line having a different roundel might cause central area passengers to avoid it, and continue to press onto Central Line trains, despite these having less capacity. Now, this may be the intention; to promote the new line as a sort-of 'prestige' line, a 'first-class', as it were. In which case, fine. It needs its own branding. BUT, if it is intended for use to ease central area congestion, then the non-conformity with the rest of the Underground may be counter-productive. It's done, so only time will tell! I doubt that anyone will care. After all most regular rail travellers have got used to a whole RGB set of colour schemes, and don't seen to be unduly bothered.
|
|
|
Post by 100andthirty on Nov 28, 2021 13:00:49 GMT
Pedantically, Interoperable Railways - all UK railways except those on the exemption list - are only required to comply with the TSI-PRM*. RVAR was retained solely for non interoperable railways.
* TSI has now become National Technical Specification Notice since BREXIT.
|
|
|
Post by 100andthirty on Nov 14, 2021 22:36:30 GMT
If I recall correctly, there are three nominal service brake rates, a higher rate for tunnels at, from memory, 1.05m/s2 for tunnel, 0.75m/s2 for open running with a lower circa 0.6m/s2 rate for autumn. As I understand it, but could well be wrong, the choice of open brake rates can be selected from the control room.
|
|
|
Post by 100andthirty on Nov 14, 2021 22:30:29 GMT
The ac Traction package software can be set to precisely emulate the dc package. I don't actually know whether it will be like this or whether higher performance will be sought. The two key features that avoid jerkiness are a) the rate at which acceleration rate is changed eg from acceleration to coasting, known as the jerk rate, a property of the traction software,and b) the hysteresis built into ATO about which the ATO controller manages constant speed running. This means that the ATO will tell the train to accelerate and when it reaches the speed limit, say, 60km/h, the ATO will tell the train to coast. The acceleration rate will be eased off (known as the jerk rate - like gently removing pressure on the accelerator pedal in a car) and the train will coast. If the speed falls below a lower speed (the lower limit of the hysteresis,for this example, say, 57km/h) the ATO will tell the train to reaccelerate.
I don't know the exact settings but I think that Central line has a larger hysteresis than on the Jubilee and Northern and a smoother feeling jerk rate.
If the acceleration rate is changed, the ATO - a closed loop controller - will compensate for small changes.
|
|
|
Post by 100andthirty on Oct 13, 2021 9:07:46 GMT
Yes and no - they prevented the train hitting the station building, which would likely have resulted in more injuries (although being an early-morning contra-peak train helped with that considerably too), but they didn't restrain the train completely. Modern friction buffers are designed to slide along the track for some distance gradually slowing the train rather than bringing it to an abrupt stop. However, installing these at Enfield Town would mean moving the stopping point quite a way towards London and I don't know whether that can be done without platform extensions, and in turn I don't know how close the current platforms are to pointwork. Google Maps air photo conveniently includes an 8-car train in platform 2. Very approximately there is about 3.5 metres between the north of the train (which I will assume is at the stopping mark) and the buffers and about 4.5 metres between the buffers and the wall of the station building. There is about 14 metres between the south end of the train and the platform end barriers. While you could hang over that slightly with the cab, I think any significant distance is going to make signal sighting difficult. That gives a total of about 21 metres maximum between the end of the train and the station building. For reference, the buffers for the LO platforms at Stratford are approximately 14 (p1) and 19 (p2) metres from the first solid object, but the apparent stopping marks are 84m and 11m respectively from those buffers. One consideration to add is that the class 710 unit don't have the buffers to interact with the buffer stops! If you compare the stops at Enfield with those designed for more modern stock, for example at Euston, you'll see there is pocket designed for the coupler. The coupler is designed to absorb quite a lot of the energy in a low speed collision, but won't work so well if not captured. There is probably room for the type of friction buffers, with coupler pockets as seen at Euston, to be fitted at Enfield Town. These only take a few metres of space. From the Sectional Appendix the platforms are all >180m (equivalent to 9 x 20m coaches) and the class 710 4-car units are just under 83m long. It is possible that the signal positions may need to be adjusted, but as the class 710s are not gangwayed, there may not be so much of an issue for signal sighting compared with the class 317 units which ran some of the services in the past. My take on the incident is this: Firstly the class 710 does have buffers - or anti-climbers - hidden behind the blue fibreglass either side of the coupler. What seems to have happened here is that the force of the collision has caused the fishplates in the last rail joint to come adrift allowing the buffer to move backwards until the buffer (or rails on which it was mounted) to hit something solid at which point it pivoted upwards with the result we've seen in the photos. The buffer structure itself seems remarkably undamaged. Even friction buffers rely on the strength and integrity of the track on which they're mounted, and the attention to detail in terms of the amount of grip they apply to the rails, something that is very difficult to test.
|
|
|
Post by 100andthirty on Oct 3, 2021 6:50:11 GMT
Some unsafe practice in that video! Used to do that all the time as a Northern line guard, on a sunny day once out of the tunnel that was normal position. Back in the day, all sorts of things were done which are, rightly, not allowed now. I still remember going on the track before there was any suggestion that high viz clothing might be a good idea.
|
|
|
Post by 100andthirty on Oct 2, 2021 7:03:12 GMT
Some unsafe practice in that video!
|
|
|
Post by 100andthirty on Oct 1, 2021 11:10:49 GMT
All D stock trains single ended units had a wedgelock coupler at the cab end complete with a full front face, "dutch ovens" and, if I recall correctly, some basic wiring to feed the emergency brake control. It was the 1973 tube stock single ended units that omitted the front face/dutch ovens. Given the scale of the conversion carried out by Vivarail, making the couple fully wired to allow multiple unit operation would be comparatively straightforward. Companies such as Voith can modify/overhaul or supply parts.
|
|
|
Post by 100andthirty on Aug 31, 2021 9:20:00 GMT
There is an event on 20th September where Dave Hooper and Paul Wright from Siemens will talk to the Institution of Mechanical Engineers about the new trains. It is open to non members but you have to register an account and book. nearyou.imeche.org/eventdetail?id=19290I'm sure a lot will be learned and at these meetings questions are usually taken........but not necessarily answered!
|
|
|
Post by 100andthirty on Aug 28, 2021 18:33:02 GMT
Three trains are nearing completion. Ground works for new sidings in Beckton depot have begun I thought it was much more than just new sidings. The works at Beckton are indeed more extensive that "new sidings", but some of the new sidings need to be completed to release space for other work.
|
|
|
Post by 100andthirty on Aug 27, 2021 18:48:20 GMT
zbang: ATO can be consistently slower if the whole system hasn't been optimised - especially the timetable! In the tunnel at least, ATO can significantly reduce the run-in time to stations compared with the average driver; one of the most significant benefits of ATO. I accept the best driver might equal the ATO performance but to do so consistently is challenging to say the least. Variable driver performance is a major obstacle to delivering the required frequency. Last time LU observed manual driving in a scientific way, the operators were surprised at the degree of variability compared with the Victoria line - only ATO line in use at the time.
Adhesion: There is some sort of feedback system from the trains to the control room about adhesion levels Reporting tools are in place or being developed to feed back wheel slide performance to the control room. This is necessary as, if the two axles whose speed is monitored by the ATP disagree by more than a small amount the train applies the emergency brake. On S stock this applies in motoring as well as braking as the trains have all axles motored. This will be helped by sanding systems on the trains but I don't know if sanding has yet been commissioned.
|
|
|
Post by 100andthirty on Aug 25, 2021 14:45:10 GMT
ATO is ALWAYS going to deliver a more consistent and predictable service than manual driving. All trains are driven the same and up to the maximum the infrastructure will allow. This leads to the time taken over flat junctions to be minimised whilst always observing the speed restriction. The existence of the flat junctions and that slightly lower nominal brake rates are used on SSR compared with the Victoria line means that the top capacity has always been lower for SSR at 32TPH compared with 36TPH on the Victoria line. What observers are seeing right now are, in all probability, caused by the following:
1) Trains running to the existing timetable will feel like they're being held up. Loading new timetables will speed up the trains, provided the timetables take account of the higher performance available from the trains when in ATO 2) Despite extensive modelling, there are always tweaks to be made based on observations in service. This might mean speeds need to be tweaked, that the automatic speed controller (part of the ATO) might need some adjustment to respond better to how the train behaves, and 3) Staff in the controller room will still be learning their craft as they have control over acceleration and braking rates to help with adhesion management.
|
|
|
Post by 100andthirty on Aug 23, 2021 12:17:31 GMT
The expression "to examine the feasibility of producing a viable business case for implementing driverless trains" sounds strangely convoluted. Clearly to "examine the feasibility for implementing driverless trains" would be pointless because it's clearly feasible, just a matter of cost and risk. I think therefore that the "feasibility" refers directly to "viable business case" and sows the seeds of doubt before the job is even started. When the PM was Mayor TfL did an immense amount of work on the feasibility of driverless trains - with no attendant. It was just about possible to make a business case. As soon as there's a guarantee of a trained person on the train, the business case fails. The overwhelming benefit of automation is delivered by ATO, and having a driver observe the closing of the doors and starting has little or no disbenefit. Having the driver open the doors avoids the need for independent systems verifying that the train has actually stopped in the right place. LU determined at one point that there was a quantifiable delay between the train stopping and the driver opening the doors. This led to a proposal for automation. When examined in detail it was found that the delay was mostly down to the delay in the ATO deciding that the train had actually stopped and the drivers were reacting very quickly once the door controls were enabled. Thus the only discernible benefit of the "driverless" the elimination of staff on the train and the flexibility to add to the service without the constraint of finding an attendant. So the 2017 study (I think I have the date correctly) that was "leaked" by ASLEF showed there was no business case. By the way, for the current study, LU is seeking methods for controlling risk at the Platform Train Interface that involves systems/technologies that might be simpler/cheaper that Platform Screen Doors. www.find-tender.service.gov.uk/Notice/017125-2021
|
|
|
Post by 100andthirty on Aug 6, 2021 9:53:43 GMT
I remember such a study for the Victoria Line Upgrade. As a result platform cameras and cab monitors were fitted to the new trains. Part of the problem identified in the study was that the existing mirrors and monitors had to remain suitable for the old trains whilst the new trains needed slightly different stopping positions. I can see this issue being replicated on DLR It will be on the Picc, and was for S stock on the 4LM. Drifitng off topic, LU's standard approach of on platform cameras and in cab monitors will continue on the Piccadilly - Panasonic ADL division is the contractor if I recall correctly. Although that problem is solved, LU will still have to do thorough surveys to identify the work necessary to optimise the stopping position with respect to constraints on hump location and starter signals. I'm expecting to see a number of starter signals having to be moved. Indeed there may have to be temporary arrangements at some locations whilst both old and new trains are running. This was necessary for S stock.
|
|
|
Post by 100andthirty on Aug 6, 2021 6:53:10 GMT
I agree, it does seem strange, but from my wanderings over a significant proportion of the DLR back in 2018 , I had cause to check out the view of the mirrors and monitors and a large proportion left much to be desired. I would have judged them barely adequate for occasional use. Perhaps they've been improved. As I said earlier, I haven't been out on the DLR for 18 months! I've been told there is an enabling project tasked to improve/modify PTI mirrors/monitors for use with the new trains, taking account of the sighting cones available from the so-called Emergency Driving Position. Not an easy task there eh! I remember such a study for the Victoria Line Upgrade. As a result platform cameras and cab monitors were fitted to the new trains. Part of the problem identified in the study was that the existing mirrors and monitors had to remain suitable for the old trains whilst the new trains needed slightly different stopping positions. I can see this issue being replicated on DLR
|
|
|
Post by 100andthirty on Aug 3, 2021 7:09:45 GMT
When 1983 tube stock was planned it was intended to buy 30 trains. The original order was halved due to falling passenger numbers and poor finances. Then Fair's Fare happened and suddenly more trains were needed. The second batch was a separate order with changes to fix easily fixed aspects of the original trains that were "not good".
The Deep Tube Piccadilly line order is not split and LU will expect all trains to be the same, subject only to the number of inevitable modifications that can be incorporated at build rather than being retrofitted.
As for the changeover of production lines, LU will have a delivery schedule which they will expect to be maintained. Speculating, I would guess that Siemens will start by assembling manufactured bodyshells in Goole, with perhaps bodyshell manufacture coming later, similar to the way the Hitachi plant developed. I am sure that bogies and traction equipment will continue to come from mainland Europe.
Having the factory in Goole is a very visible statement that investment in London is good for the "levelling up" agenda and I'm sure the Mayor, TfL and Siemens will play that card for all it's worth.
|
|
|
Post by 100andthirty on Jul 27, 2021 11:43:23 GMT
Obviously I've not seen the new stock, but in the renders I have seen it is not at all obvious that the view will be worse than the current stock. Indeed if it were I would have thought that the design would not have been given approval. I agree, it does seem strange, but from my wanderings over a significant proportion of the DLR back in 2018 , I had cause to check out the view of the mirrors and monitors and a large proportion left much to be desired. I would have judged them barely adequate for occasional use. Perhaps they've been improved. As I said earlier, I haven't been out on the DLR for 18 months!
|
|
|
Post by 100andthirty on Jul 27, 2021 8:27:40 GMT
Time to drop the pretence that DLR trains are 'driverless', perhaps, and give the driver proper facilities. Bearing in minf that I haven't travelled on DLR for more than 18 months........ for the overwhelming proportion of the total journeys, the Passenger Services Agent (PSA) is free to roam around the train allowing the PSA to check the PTI and close the doors from any platform side door on the train. This gives the PSA the best possible view of the platform, and a view that is MUCH, MUCH better than is available from the driving position. In my opinion the current DLR mirrors and monitors are not fit for purpose.
|
|
|
Post by 100andthirty on Jul 26, 2021 13:48:11 GMT
The new DLR trains feature a similar driving position to current trains. The ā€¯Driverless trains on London Undergroundā€¯ report, dated August 2020 and leaked to ASLEF in late October ( link ), made a case for retaining current modern operating methods on LU. It claimed the current secure cab environment allows staff to concentrate on their job free from distraction by customers. It also mentions that at peak times and on more crowded parts of the DLR, the Train Attendant now performs duties from the front control panel, to manage the increased safety risks now being experienced. And yet they are not to be given a secure cab environment for safe working! see videoThe new train mock up shows similar features to those on all new trains over the last few years. That the driver sits further back from the windscreen than before and, in this case the pillar on the left hand side is bigger and the front window is narrower. The view of the mirrors (mostly) and monitors (occasionally) isn't very good on the existing trains and a feel for the PSAs who have to manage closing the doors safely from this position. Unless some sort of in cab OPO/DOO CCTV system is to be fitted, I really don't see how this aspect of the new trains will work. The cynic in me saw the sliding panel that closes off entry into the driving position and wondered what the staff representative's opinion might be.
|
|
|
Post by 100andthirty on Jul 15, 2021 14:21:00 GMT
With such deep corner pillars compared with the existing trains I wonder how that impacts sighting of the PTI in what on LUL would be called OPO Mirrors? This is already an issue with the existing trains as a ride in the "driver's seat" as a passenger will testify. Quite how they will manage with a narrower windscreen and sitting further back is a mystery to me. Perhaps the PSA is supposed to look out of the side window.
|
|
|
Post by 100andthirty on Jul 5, 2021 18:44:37 GMT
FOBA thats the one .... for some reason I did remember it began FO.... as one wit translated that as flipping off brake application or similar terminology I didn't want to confuse with other FO... XLAs where FO mean fibre optic. What would we do without these acronymns. Or making up alternatives. This is true for the Sub surface lines where the Seltrac and the traction equipment have some sort of communication. On Jubilee and Northern another means had to be found and although the aim was for the friction only applications to be made in the open, it doesn't always work out that way.
|
|