140mph

[stanley T]

Don't the SNCF run at 140mph (225 km/h) with flashing greens with TGVs on some conventional lines - on parts of the Tours-Bordeaux line, I think. Amazed that they get up to that speed on 1500V DC power. I don't think TVM is installed, conventional signalling?

 

[swt_passenger]

When ERTMS eventually gets installed on the SWML (I'd assume not within the next decade), would west of Southampton Central benefit much if trains could tilt?

No. The stopping patterns west of Southampton would mean the overall benefits would be marginal. It has been said before that the WCML is really the only line in the country that benefits much from a tilt system, on something like the ECML the majority of the route is straight enough that tilt doesn't give a useful end to end benefit. I'd expect that would apply to the SWML when considered over it's full length.

 

[TheKnightWho]

No. The stopping patterns west of Southampton would mean the overall benefits would be marginal. It has been said before that the WCML is really the only line in the country that benefits much from a tilt system, on something like the ECML the majority of the route is straight enough that tilt doesn't give a useful end to end benefit. I'd expect that would apply to the SWML when considered over it's full length.

Not even the MML?

 

[superkev]

Not even the MML?

Ecml gets fairly curvy north of Darlington. Wasn't someone proposing tilting paddedcellinos on this route.
K

 

[swt_passenger]

Not even the MML?

Apparently not, according to previous discussions it is easier to carry on doing incremental changes to give 125 mph with ordinary stock.

--- old post above --- --- new post below ---

Ecml gets fairly curvy north of Darlington. Wasn't someone proposing tilting paddedcellinos on this route.
K

Grand Central. One of the reasons it didn't happen was because their proposals were not considered financially sound. Or put another way NR and ORR disagreed.

 

[gsnedders]

Don't the SNCF run at 140mph (225 km/h) with flashing greens with TGVs on some conventional lines - on parts of the Tours-Bordeaux line, I think. Amazed that they get up to that speed on 1500V DC power. I don't think TVM is installed, conventional signalling?

They have KVB installed on it, so there's active speed control along the whole line. France requires in-cab signalling over 160km/h. I believe in principle the primary movement authority comes from KVB displaying a non-zero speed until you are at 160km/h or below, but I expect someone else knows better!

 

[AM9]

Don't the SNCF run at 140mph (225 km/h) .... Amazed that they get up to that speed on 1500V DC power. ...

The world record for an electric traction train of 331km/h was made by BB9004 on 1500VDC in 1955. That record held until 1981 when an ac powered TGV clocked 380km/h.

 

[QueensCurve]

The world record for an electric traction train of 331km/h was made by BB9004 on 1500VDC in 1955. That record held until 1981 when an ac powered TGV clocked 380km/h.

Yes.

In order to achieve this, they had to increase the voltage on the OHLE and increase the voltage of the feeder lines to prevent voltage drops on the test run. Additional physical tension was put in the wires. There were changes to the gear ratio and other modifications. The loco pulled a 3 car train with rubber fairings between the cars (as originally fitted on APT-P?) to reduce drag.

See: https://translate.google.co.uk/translate?hl=en&sl=fr&u=http://bpcv.free.fr/page0.html&prev=search

 

[craigybagel]

Whatever might happen could equally happen today if a fault was detected in the tilt mechanism and it reverted to non-tilt mode.

Indeed. I'm pretty sure the speeds the trains run through curves with Tilt working would be perfectly safe without tilt (in terms of it wouldn't cause the train to derail) but uncomfortable for passengers. Having had the tilt fail at 125mph on a voyager whilst pushing a cart down the aisle I can certainly vouch for that.....

 

[QueensCurve]

Indeed. I'm pretty sure the speeds the trains run through curves with Tilt working would be perfectly safe without tilt (in terms of it wouldn't cause the train to derail) but uncomfortable for passengers. Having had the tilt fail at 125mph on a voyager whilst pushing a cart down the aisle I can certainly vouch for that.....

Riding in the front car of a Pendolino is pretty uncomfortable anyway.

 

[edwin_m]

Indeed. I'm pretty sure the speeds the trains run through curves with Tilt working would be perfectly safe without tilt (in terms of it wouldn't cause the train to derail) but uncomfortable for passengers. Having had the tilt fail at 125mph on a voyager whilst pushing a cart down the aisle I can certainly vouch for that.....

I agree it would be uncomfortable but nowhere near overturning (the overturning speed is pretty much identical whether tilt is active or not). However I believe a worst case tilt system failure could take the train out of gauge, so if anything fails all the bodies are locked central and TASS enforces the non-tilt speed restrictions. Enforcing these immediately would trigger an emergency brake so I assume there is some kind of soft enforcement to allow for an orderly deceleration.

 

[TheKnightWho]

I agree it would be uncomfortable but nowhere near overturning (the overturning speed is pretty much identical whether tilt is active or not). However I believe a worst case tilt system failure could take the train out of gauge, so if anything fails all the bodies are locked central and TASS enforces the non-tilt speed restrictions. Enforcing these immediately would trigger an emergency brake so I assume there is some kind of soft enforcement to allow for an orderly deceleration.

That just gave me quite an interesting idea - how about steep banking around severe corners, but with tilting activated to go against the curve when the train is going too slow or is stopped. That could increase the overturn speed considerably without causing problems for when the train isn't moving (or would you be at risk of causing overturn when stopped instead?).

 

[craigybagel]

I agree it would be uncomfortable but nowhere near overturning (the overturning speed is pretty much identical whether tilt is active or not). However I believe a worst case tilt system failure could take the train out of gauge, so if anything fails all the bodies are locked central and TASS enforces the non-tilt speed restrictions. Enforcing these immediately would trigger an emergency brake so I assume there is some kind of soft enforcement to allow for an orderly deceleration.

If I remember correctly from an article when TASS was being developed, part of the design is that in areas where TASS is active if the tilt system fails the train will still stay in guage?

 

[SpacePhoenix]

If the tilt fails, will the TASS move the tilt to the central position straight away or in a controlled way (slowly) to avoid a rough ride for passengers?

 

[edwin_m]

That just gave me quite an interesting idea - how about steep banking around severe corners, but with tilting activated to go against the curve when the train is going too slow or is stopped. That could increase the overturn speed considerably without causing problems for when the train isn't moving (or would you be at risk of causing overturn when stopped instead?).

That might be possible if all trains on a route tilted, but I don't think that is so anywhere in the world. The amount of cant is limited by passenger discomfort and wear on the lower rail if trains stop or pass at much lower speeds than the "equilibrium speed" that the cant is designed for.

Incidentally I believe the APT would tilt the "wrong" way if it went round a curve at lower than the equilibrium speed, as its logic was simply to adjust the tilt until the sensors detected zero lateral acceleration. Not sure if the Pendolino, which doesn't attempt to get to zero lateral acceleration, would also tilt the wrong way.

 

[Taunton]

I think that for speeds over 125mph you need cab signalling which isn't fitted to lines other than HS1.

Joe Duddington managed it nearly 80 years ago by leaning over the side

 

[LNW-GW Joint]

Don't the SNCF run at 140mph (225 km/h) with flashing greens with TGVs on some conventional lines - on parts of the Tours-Bordeaux line, I think. Amazed that they get up to that speed on 1500V DC power. I don't think TVM is installed, conventional signalling?

They will stop doing that from next year when the Bordeaux LGV opens, bypassing the classic line from Tours.

 

[SpacePhoenix]

Does 140mph running result in much extra vertical oscillation of the catenary compared with 125mph running?

 

[najaB]

Does 140mph running result in much extra vertical oscillation of the catenary compared with 125mph running?

Not if the tension is increased.