Speed of LU lines

[simple simon]

BR should have kicked up a fuss when the Met Main Line had its speed limit reduced from 70mph to 60mph in circa 1990.

When Chiltern trains start going to Milton Keynes via Bletchley and the Cambridge Oxford line is fully reopened Met Main Line speeds should not so much be restored as raised, at a minimum to 80mph, if not 90mph. There is too much desire for slowness with respect of travel speeds.

In addition, AWS ramps should be fitted so that mainline trains don't need trainstops. (This should be funded from DfT or Chiltern Trains, not TfL). Then Chiltern could even route their push pull trains with Mk3 carriages via this line.

 

[philthetube]

S Stock are electronically locked at:
62mph maximum in weak-field areas on MET; 47mph maximum in weak-field areas on District/H&C.
42mph maximum in other areas.

They are unable to motor past these speeds however they will go faster downhill, 70 would probably be achievable through Neasden, though probably a little bumpy.

BR should have kicked up a fuss when the Met Main Line had its speed limit reduced from 70mph to 60mph in circa 1990.
BR didn't really have the right to kick up a fuss about what lul did with their own property

When Chiltern trains start going to Milton Keynes via Bletchley and the Cambridge Oxford line is fully reopened Met Main Line speeds should not so much be restored as raised, at a minimum to 80mph, if not 90mph. There is too much desire for slowness with respect of travel speeds.


In addition, AWS ramps should be fitted so that mainline trains don't need trainstops. (This should be funded from DfT or Chiltern Trains, not TfL). Then Chiltern could even route their push pull trains with Mk3 carriages via this line.

The line is not suitable for 90mph running, Chiltern do not have stock capable of doing those speeds uphill or stopping downhill, linespeed is currently reduced to 40mph during leafall .
Chiltern have more than enough trains with trip cocks fitted and unless they were going to pay for platform lengthening as well, and additional staff for dispatch on curved platforms this would be pointless.
Having extra systems in place creates extra chances for failures.

 

[Mojo]

In addition, AWS ramps should be fitted so that mainline trains don't need trainstops. (This should be funded from DfT or Chiltern Trains, not TfL). Then Chiltern could even route their push pull trains with Mk3 carriages via this line.

Do you mean TPWS rather than AWS? As AWS isn't a protection system and won't stop a train if it were to pass a red signal.

 

[edwin_m]

When Chiltern trains start going to Milton Keynes via Bletchley and the Cambridge Oxford line is fully reopened Met Main Line speeds should not so much be restored as raised, at a minimum to 80mph, if not 90mph. There is too much desire for slowness with respect of travel speeds.

In addition, AWS ramps should be fitted so that mainline trains don't need trainstops. (This should be funded from DfT or Chiltern Trains, not TfL). Then Chiltern could even route their push pull trains with Mk3 carriages via this line.

Chiltern's MK trains will run via High Wycombe not via Amersham, so will only use the former Met main line between Aylesbury and Quainton Road, where LU has had no involvement for many decades.

The re-signalling of the Metropolitan will eventually eliminate trainstops and is planned to include NR-style signals where Chiltern also uses the route (with a Met train fitted with the TBTC signalling seeing a blue aspect). I assume, but I don't recall seeing it definitely stated, that this scheme will also provide TPWS so the trainstops on the shared section don't need to be retained just for Chiltern. This would allow Chiltern to dispense with the on-train tripcocks and probably remove restrictions on the types of unit that could run via Amersham.

 

[bramling]

For the best part of the last 20 years A stock were limited to 50mph; Met linespeed is 60 and S8s also hit this daily.

Ha Ha
I had quite a few of SatNav timed runs in the last years before they went on A stock between Finchley Rd and HOTH running at 65.
I have also been on an S8 just once that I seem to remember maxed out at about 65 as well
Does anyone know if the 100KPH max is rigidly fixed or is it like the HSTs when they first came out whereby there were many drivers who were members of the unoffical "140 mph club"
Regards Jumble

.

[/QUOTE]

It will certainly be rigidly fixed when CBTC comes in. The ATO works to a target speed, which is what is displayed to the train operator, and above that there is a small margin of a few mph up the ultimate ceiling which is known as Maximum Safe Speed. If that is exceeded than the emergency brake will be applied and the train will be brought to a stand. On the Northern the most which can be reached is about 53 mph between Kennington and Waterloo, but that is right on the cusp of the train EBing.

The Central Line has a nice feature that if the train overspeeds the emergency brake will apply, but only until the train is back within maximum safe speed. I believe current LU standards require the train be brought to a complete stand, although I've yet to hear a really good reason for why this is deemed necessary. It causes needless delay as well as risking needless wheel flats, etc.

 

[bramling]

Certain drivers would go parallel then back to inch/shunt to slow the acceleration where there was poor adhesion - though was not advisable for too long before throwing it back to full parallel..
Can't agree on the smooth stopping - it was far easier to do with an EP than with the Westcode and would imagine even more difficult on modern stock.

I don't see the difference. On stock with notches (72 & 73 stock) the driver simply aims to stop with the handle in off & release and then move it back into rheo 1 & hold or service 1 once the train has actually stopped. On stock with a fore/aft traction/brake controller (92,95 & 96) again simply throw the handle forwards into off & release as the train is coming to a stand, then once the train is stopped throw it back into a braking position. The only nuisance on these trains is that sometimes the notch between full service and emergency is weak and the handle may put itself in the emergency position, but that's more nuisance than problem. Alternatively, on these trains as there are infinite braking positions, just arrange to push the handle towards minimum brake as the train comes to a stand, which will normally result in the same effect as long as the encoder is functioning correctly.

I can't comment on S stock, although I can imagine it might be more tricky on these as to me the handle looks a little awkward and too much like a joystick - and experiencing as a passenger how many drivers motor and brake on S stock appears to confirm my thoughts on this.

The only exception is where the platform is on a steep gradient (e.g. West Finchley) in which case it may be more preferable to stop with some brake on, but even then it's quite possible to stop in off & release if one is sufficient confident.

 

[Mutant Lemming]

I don't see the difference. On stock with notches (72 & 73 stock) the driver simply aims to stop with the handle in off & release and then move it back into rheo 1 & hold or service 1 once the train has actually stopped. On stock with a fore/aft traction/brake controller (92,95 & 96) again simply throw the handle forwards into off & release as the train is coming to a stand, then once the train is stopped throw it back into a braking position. The only nuisance on these trains is that sometimes the notch between full service and emergency is weak and the handle may put itself in the emergency position, but that's more nuisance than problem. Alternatively, on these trains as there are infinite braking positions, just arrange to push the handle towards minimum brake as the train comes to a stand, which will normally result in the same effect as long as the encoder is functioning correctly.

I can't comment on S stock, although I can imagine it might be more tricky on these as to me the handle looks a little awkward and too much like a joystick - and experiencing as a passenger how many drivers motor and brake on S stock appears to confirm my thoughts on this.

The only exception is where the platform is on a steep gradient (e.g. West Finchley) in which case it may be more preferable to stop with some brake on, but even then it's quite possible to stop in off & release if one is sufficient confident.

Just seemed more awkward on 73s - you could ease just little back on with EP on 38/59/A60s but with service one on a 73 you bang in 7lbs so a slight misjudgement not so noticeable on conventional stock becomes far more so on 'modern' stock. The 72s was more an issue with the appalling rheos of the time - certain of the poorer drivers had developed a bad habit of dropping the handle as part of 'normal' braking due to their mistrust of the rheo. They were much maltreated and poorly maintained by crews and depots alike am surprised they have lasted so long.

 

[bramling]

Just seemed more awkward on 73s - you could ease just little back on with EP on 38/59/A60s but with service one on a 73 you bang in 7lbs so a slight misjudgement not so noticeable on conventional stock becomes far more so on 'modern' stock. The 72s was more an issue with the appalling rheos of the time - certain of the poorer drivers had developed a bad habit of dropping the handle as part of 'normal' braking due to their mistrust of the rheo. They were much maltreated and poorly maintained by crews and depots alike am surprised they have lasted so long.

Depends how good the driver is - it's still quite possible to do it. Naturally a rogue train is possible with any fleet - although agreed it's rather more likely on a 72 stock than a 95 stock. Still get rogue 95 stocks though - can have a train which is perfectly good for many stations then suddenly at one station the brakes die at the last minute. However, this is all more to do with the train not putting enough brake on when required - to get a smooth stop we're talking about taking the brake off, which is generally less of an issue.

 

[rebmcr]

AWS ramps should be fitted so that mainline trains don't need trainstops.

Have a good think and let us know when you've spotted the flaw here.

 

[philthetube]

Have a good think and let us know when you've spotted the flaw here.

Underground trains don't need trainstops either, (I wonder why not)