Bi-modes: can they switch while on the move?

[nw1]

Just a quick question and just curious: can bi-modes switch from electric to diesel and v.v when on the move?

Just wondering whether, if the switch point is somewhere they don't stop (such as Newbury for the faster services to the southwest), they could switch there or whether they would have to switch at the last scheduled stop (Reading in this case).

Thanks.

 

[tiptoptaff]

800s can and do, yes.

 

[LNW-GW Joint]

Change to/from electric mode has to be done at designated places, which for 80x can be on the move at speed (eg east of Didcot towards the Oxford line).
Northern's 769s switch mode while stopped at Bolton station (BR dual-system EMUs were never very good at switching mode on the move).
The Stadler 755 is the other current bi-mode type - I assume they can do dynamic switching.

 

[Shwam3]

755s can changeover on the move, but all current changeovers are done statically at stations.

 

[Wilts Wanderer]

With the GWML the changeover from electric to diesel can occur anywhere, at any speed. The changeover from diesel to electric can occur on the move at specially designated locations (such as Moreton Cutting for services from Oxford) at linespeed, or anywhere under the wires at 20mph max. The issue being the impact stress on the catenary of the pantograph lifting, only certain locations have the appropriate reinforced design to cope with it.

 

[Bigman]

Changeover on the Chieftain takes place North of Stirling.

 

[matchmaker]

Changeover on the Chieftain takes place North of Stirling.

The changeover takes place between Cornton level crossing and Kippenross tunnel in both directions. It should happen automatically.

 

[swt_passenger]

With the GWML the changeover from electric to diesel can occur anywhere, at any speed. The changeover from diesel to electric can occur on the move at specially designated locations (such as Moreton Cutting for services from Oxford) at linespeed, or anywhere under the wires at 20mph max. The issue being the impact stress on the catenary of the pantograph lifting, only certain locations have the appropriate reinforced design to cope with it.

It’s been reported by GWR insiders in earlier threads that the OHLE is not specially reinforced, it’s just that NR want to limit the areas they need to additionally inspect

 

[dk1]

Only where specially authorised.

 

[Bill57p9]

IIRC the TPE 802s also changed over automatically when first in service between Edinburgh & Newcastle as there was a significant length of overhead electrification with insufficient supply for them and the LNER traffic.

 

[nw1]

OK, many thanks for the replies, looks like they can but in specific locations only.

I haven't travelled much within the UK in the past two or three years (barely been out of Hampshire - though I have been abroad!) so I still haven't sampled a bi-mode. Last time I was at Reading, somewhere I had previously passed through regularly, it was still all HSTs and Turbos!

 

[swt_passenger]

IIRC the TPE 802s also changed over automatically when first in service between Edinburgh & Newcastle as there was a significant length of overhead electrification with insufficient supply for them and the LNER traffic.

But in that case it was later explained that TPE don’t actually let their drivers rely on the automatic changeover equipment that NR provided at Chathill and Longniddry, so their 802s stay on diesel between station calls.

However I believe NR still think that “automatic power changeover” (APCO) at pan up/down locations is worthwhile, I noticed a while back there’s another example at Werrington junction where the Lincoln trains leave/join the ECML.

 

[tiptoptaff]

But in that case it was later explained that TPE don’t actually let their drivers rely on the automatic changeover equipment that NR provided at Chathill and Longniddry, so their 802s stay on diesel between station calls.

However I believe NR still think that “automatic power changeover” (APCO) at pan up/down locations is worthwhile, I noticed a while back there’s another example at Werrington junction where the Lincoln trains leave/join the ECML.

I'm sure GWR changeover is done manually - I don't sign IETs and have only had a handful of trips up front with DIs on sections where it matters.

But I'm also sure there are APCO bailaises installed in places. Filton Bank is one that I can think of, adjacent to Stoke Gifford depot

 

[MotCO]

Going the other way (i.e. from electric to diesel), the diesel engine (I understand) has to be warmed up before full revs can be applied, and this obviously needs to be done before the wires run out.

 

[tiptoptaff]

Going the other way (i.e. from electric to diesel), the diesel engine (I understand) has to be warmed up before full revs can be applied, and this obviously needs to be done before the wires run out.

It's best practice, yes. But if you had to pan down and fire up the engines immediately, such as after an ADD activation, you can start them

Edit
On 800/802s, that is

 

[LNW-GW Joint]

Going the other way (i.e. from electric to diesel), the diesel engine (I understand) has to be warmed up before full revs can be applied, and this obviously needs to be done before the wires run out.

Northern's 769s seem to change during a normal station call at Bolton.
The diesel engines fired up after we stopped and the pan dropped, and we were off again less than a minute later.
Granted the engines would have been used several times that day already, being switched off periodically for the best part of 2 hours while using the wires.

 

[norbitonflyer]

However I believe NR still think that “automatic power changeover” (APCO) at pan up/down locations is worthwhile, I noticed a while back there’s another example at Werrington junction where the Lincoln trains leave/join the ECML.

Eh? The only passenger services that leave the ECML at Werrington are run by EMR, which has no bimodes - and as far as I am aware is not planning to run those it has on order on their Peterborough - Lincoln services. LNER's London - Lincoln services do use bimodes, but they stay on the ECML as far as Newark.

 

[swt_passenger]

Eh? The only passenger services that leave the ECML at Werrington are run by EMR, which has no bimodes - and as far as I am aware is not planning to run those it has on order on their Peterborough - Lincoln services. LNER's London - Lincoln services do use bimodes, but they stay on the ECML as far as Newark.

My mistake about Lincoln, but it must be there for something, as shown in the SA. Might it be only for engineering work diversions?

I see there are also APCO sites shown about 2 miles from Newark approaching from the south, and in platform 3.

 

[Trackman]

755s can changeover on the move, but all current changeovers are done statically at stations.

I reckon this is done in case something goes wrong, like Northern's 769s.
At least you are at a station and not in the middle of nowhere.

 

[swt_passenger]

I reckon this is done in case something goes wrong, like Northern's 769s.
At least you are at a station and not in the middle of nowhere.

319s weren’t capable of changeover on the move, AIUI from previous threads they remain incapable of doing so as the diesel generators only emulate the previous DC system.

For completeness the GWR version can change from third rail DC to generator DC while moving, but still has to stop for AC changeover.

 

[AM9]

319s weren’t capable of changeover on the move, AIUI from previous threads they remain incapable of doing so as the diesel generators only emulate the previous DC system.

For completeness the GWR version can change from third rail DC to generator DC while moving, but still has to stop for AC changeover.

Didn't somebody here state that the GWR 769s could (and might in service) changeover on the move from Diesel to 3rd rail and vice versa?

 

[swt_passenger]

Didn't somebody here state that the GWR 769s could (and might in service) changeover on the move from Diesel to 3rd rail and vice versa?

That’s what I just wrote? Generator = Diesel - or were you just adding the opposite mode change? IIRC they would change in the platform southbound at Guildford, but on the move elsewhere. Presumably because Guildford station is so close to Shalford Junction it makes little difference.

 

[AM9]

That’s what I just wrote? Generator = Diesel - or were you just adding the opposite mode change? IIRC they would change in the platform southbound at Guildford, but on the move elsewhere. Presumably because Guildford station is so close to Shalford Junction it makes little difference.

I was referring to an earlier reference to that capability and that GWR were planning to use it. There was discussion then about whether Shalford junction would be the changeover point or whether it would still run on diesel through the Guildford tunnels. I think there was even a suggestion as to whether it might be viable to extend the 3rd rail to Shalford station (subject to clearance of more 3rd rail) so that they could clear the mainline junction more quickly on DC electric mode.

 

[norbitonflyer]

I would guess one of the issues is the potential consequences if a switch fails to happen - a pantograph fails to drop or an engine fails to start before the wires run out. In the other direction you can just carry on.

I recall that 313s used to switch dc/ac "on the fly" when negotiating the Graham Road curve, but I think only going towards Liverpool Street.

 

[Starmill]

Automatic power change over equipment is most definitely going to be a future area of focus because it supports the reduction of harmful diesel emissions in urban and enclosed-station areas. A number of the examples provided upthread are already helping to minimise air quality disbenefits such as the Cornton changeover. It was the case more than a year ago that when departing Doncaster, LNER services towards Hull would leave on AC power and then change over before leaving the wires at Temple Hirst, but Hull Trains services in the same direction would complete their changeover before departing. The same went for trains departing from York in the Leeds direction, where LNER would leave on AC then switch, while TransPennine Express would make the switch first. I imagine that the LNER approach in these examples will slowly become the norm over time.

 

[DownFast]

I'm sure GWR changeover is done manually - I don't sign IETs and have only had a handful of trips up front with DIs on sections where it matters.

But I'm also sure there are APCO bailaises installed in places. Filton Bank is one that I can think of, adjacent to Stoke Gifford depot

Yes, all changeovers on GWR are manual. APCO has been considered but there are so many parameters/complications that it wouldn't be possible to have all changeovers carried out automatically, and having a mix of manual and automatic changeovers is a recipe for operational incidents.

There are Eurobalises (ETCS balises) in places, yes, but these are what's known as 'zero balises' which tell the train to lower the pan automatically if the driver forgets to do so. There will also be balises appearing for BBASDO (Balise-Based ASDO which uses Eurobalises to determine platform number, and therefore enables correct side door enable (CSDE), which inhibits wrong-side door releases), and of course there are balises being installed on the route out of Paddington for ETCS Level 2.

It's best practice, yes. But if you had to pan down and fire up the engines immediately, such as after an ADD activation, you can start them

Edit
On 800/802s, that is

Strictly speaking, the engines on 80x should only be started if the coolant temp. is 45 degrees or more. The coolant can be pre-heated via the TMS, but GWR have told Hitachi that using the TMS to start the pre-heat and then monitoring the temperatures, all while running at up to 125mph is too much of a distraction risk, so drivers are instructed to just press the diesel button at the changeover location (although some drivers just begin the pre-heat at the start of the journey while on electric). If the engines are cold, then they will idle until the coolant warms up. If APCO were operational, the engine pre-heat would begin at a distance from the changeover location (4 miles IIRC) - the headcode data that includes the stopping pattern, times etc. can also - if included in the database - include changeover locations and GPS co-ordinates for the engine pre-heat to begin.

I was referring to an earlier reference to that capability and that GWR were planning to use it. There was discussion then about whether Shalford junction would be the changeover point or whether it would still run on diesel through the Guildford tunnels. I think there was even a suggestion as to whether it might be viable to extend the 3rd rail to Shalford station (subject to clearance of more 3rd rail) so that they could clear the mainline junction more quickly on DC electric mode.

Dynamic power changeover for GWR 769s is carried out at Shalford Jct when switching from diesel to DC when coming from Redhill/Gatwick, but statically at Guildford for trains heading towards Redhill/Gatwick. This is because the changeover from diesel to DC is much quicker and therefore has less of a distraction risk than changing from DC to diesel, and because changing from DC to diesel dynamically prior to Shalford Jct would basically mean doing so in a tunnel. So eastbound trains (heading to Redhill/Gatwick) will run on diesel in the tunnels, but trains in the opposite direction (towards Reading) won't.

Dynamic changeovers are also approved at Ash (DC to diesel) and Aldershot Sth Jct (diesel to DC) for trains not booked to call at Ash, and at Reading Spur Jct (DC to diesel and vice versa) for trains heading to/from the higher number platforms at Reading via the Low Level line.

 

[AM9]

Yes, all changeovers on GWR are manual. APCO has been considered but there are so many parameters/complications that it wouldn't be possible to have all changeovers carried out automatically, and having a mix of manual and automatic changeovers is a recipe for operational incidents.

There are Eurobalises (ETCS balises) in places, yes, but these are what's known as 'zero balises' which tell the train to lower the pan automatically if the driver forgets to do so. There will also be balises appearing for BBASDO (Balise-Based ASDO which uses Eurobalises to determine platform number, and therefore enables correct side door enable (CSDE), which inhibits wrong-side door releases), and of course there are balises being installed on the route out of Paddington for ETCS Level 2.

Strictly speaking, the engines on 80x should only be started if the coolant temp. is 45 degrees or more. The coolant can be pre-heated via the TMS, but GWR have told Hitachi that using the TMS to start the pre-heat and then monitoring the temperatures, all while running at up to 125mph is too much of a distraction risk, so drivers are instructed to just press the diesel button at the changeover location (although some drivers just begin the pre-heat at the start of the journey while on electric). If the engines are cold, then they will idle until the coolant warms up. If APCO were operational, the engine pre-heat would begin at a distance from the changeover location (4 miles IIRC) - the headcode data that includes the stopping pattern, times etc. can also - if included in the database - include changeover locations and GPS co-ordinates for the engine pre-heat to begin.

Dynamic power changeover for GWR 769s is carried out at Shalford Jct when switching from diesel to DC when coming from Redhill/Gatwick, but statically at Guildford for trains heading towards Redhill/Gatwick. This is because the changeover from diesel to DC is much quicker and therefore has less of a distraction risk than changing from DC to diesel, and because changing from DC to diesel dynamically prior to Shalford Jct would basically mean doing so in a tunnel. So eastbound trains (heading to Redhill/Gatwick) will run on diesel in the tunnels, but trains in the opposite direction (towards Reading) won't.

Dynamic changeovers are also approved at Ash (DC to diesel) and Aldershot Sth Jct (diesel to DC) for trains not booked to call at Ash, and at Reading Spur Jct (DC to diesel and vice versa) for trains heading to/from the higher number platforms at Reading via the Low Level line.

Thanks for the info. I'm looking forward to when they start running on the NDL, especially if they are changing mode on the move.