Tram and trolleybus overhead power

[swt_passenger]

I saw a video a few days ago of trams and trolleybuses operating together in Newcastle upon Tyne city centre. It made me wonder if they generally shared the same overhead wires? So in the busiest streets the queues of trams and trolleybuses would be affecting each other‘s progress, even though they seemed to use different parts of the roads, with the trams often in the middle?

I forgot the link…

 

[Roger1973]

I don't know Newcastle at all, but the answer is 'it depends'. Yes, it was technically possible for trams to use the positive wire of the trolleybus overhead, although the wiring would have had to be in a position to suit both the track layout and the line taken by trolleybuses.

Having said that, I'm not sure how many places ran trams and trolleybuses together for any length of time - in most places, trolleybuses replaced trams after maybe a short temporary period of joint running, although in some cases, the conversion programme was stalled in the 1939-45 war and what had been meant as temporary carried on for a while.

Glasgow ran both for quite some time, although again I don't know the patch well enough to know how often they shared the same roads, or how they dealt with the overhead. As Glasgow trams (in post war years at least) had bow collectors rather than trolley poles, the risk of a bow collector short circuiting the trolleybus overhead would have had to be considered.

The only section of London where trams (on overhead wire *) and trolleybuses shared the road for any length of time was between Woolwich and Abbey Wood, some of which had two wires, some (like this bit at Abbey Wood - photograph and Flickr account not mine) - I have read that there were occasional incidents when a driver forgot which bit of road they were on and a tram tried to overtake a trolleybus (or vice versa) at the wrong place.

* - the trams on the Kingsway Subway routes north of the Thames that survived the north London trolleybus conversions were on conduit as far as Archway and Manor House, where they terminated just south of former change pits. Although I have read that tram drivers would occasionally put a pole up on the trolleybus overhead if they got stuck on a conduit dead section - although they weren't supposed to. Likewise the small bits of trolleybus route round Battersea and Tooting that overlapped with trams, the trams were on conduit there.

 

[Beebman]

My copy of 'The Tramways of Reading' by H.E. Jordan has a photo taken in 1939 of a tram in the Oxford Road using trolleybus overhead just prior to the route's conversion.

 

[Vespa]

They can share the same live wire as both operate on 600v DC, the issues are overhead junctions, types of currency collector such a fixed or swivel trolleywheel or bow collectors as you need to prevent arching causing the power breakers to pop out.

If you have a common live wire shared with both types of transport, it can work.


*I seemed to remember reading that during the wiring conversion of St Helens to Prescot loop from tram to trolleybus, the trollybus used an earthing skate while one pole is up on the live wire.

It's certainly doable.

 

[AndrewE]

See https://www.eurogunzel.com/2015/05/when-tram-and-trolleybus-wires-cross/ and lots of other Google hits... including several from this very Forum!

 

[PeterC]

*I seemed to remember reading that during the wiring conversion of St Helens to Prescot loop from tram to trolleybus, the trollybus used an earthing skate while one pole is up on the live wire.

It's certainly doable.

I remember reading about that being done somewhere but couldn't recall any details.

 

[norbitonflyer]

Were trolleybus wires usually + and - like London Transports 4-rail system, or full voltage and earth, as is done on sections LU shares with NR stock?

 

[Vespa]

Were trolleybus wires usually + and - like London Transports 4-rail system, or full voltage and earth, as is done on sections LU shares with NR stock?

Live + and earth - wire

Live wire is usually offside to the pavement, power taken from live wire run through the motors and returned to the earth wire to complete the circuit.

 

[etr221]

*I seemed to remember reading that during the wiring conversion of St Helens to Prescot loop from tram to trolleybus, the trollybus used an earthing skate while one pole is up on the live wire.

I remember reading about that being done somewhere but couldn't recall any details.

The place I recall reading about this (trolleybus running with one pole on tram overhead, with skate/trolley trailer for current return to tramtrack) being done was in Birmingham, to enable trolleybuses on one of their routes to access the depot, which was down a tram route from the trolleybus route.

LCC did have a section in the Greenwich area where there were two wires for trams, using the second wire for current return, to avoid potential issues with earth return that worried the Royal Observatory - don't know if anywhere else had this. (But two wires on a single track tramway - one for each direction - was quite common, to simplify the overhead by reducing the need for frogs)

 

[Roger1973]

LCC did have a section in the Greenwich area where there were two wires for trams, using the second wire for current return, to avoid potential issues with earth return that worried the Royal Observatory - don't know if anywhere else had this. (But two wires on a single track tramway - one for each direction - was quite common, to simplify the overhead by reducing the need for frogs)

Yes - the Eltham to Woolwich line. Photo on Flickr here (not my Flickr account, and obviously not my photo - dates from pre 1914!)

I've also read that the depot at Brixton Hill (this one - Google Street View) was opened with twin wires - it had been designed and constructed as a depot for unpowered trailer cars (presumably with the intention of using a tractor or something to get them in and out), so the running rails weren't earthed, but the use of trailer cars had been ended before it opened, and it was needed as an outstation for the Streatham Hill / Telford Avenue depot. It was modified later.

I can't think of anywhere else that had the same arrangement, but can't be sure that it didn't exist.

As well as two wires on a single track section, there were a few sections of single track in London that had separate conduit slots to avoid pointwork, example was Stockwell Road (photo here - again not my photo or Flickr account.)

 

[Taunton]

I can't think of anywhere else that had the same arrangement, but can't be sure that it didn't exist.

We discussed a while ago that Cincinnati in the USA long had this dual wire arrangement for streetcars, due to concerns about earthing issues, and a photo showed that at changeover to trolleybuses these used the same wires. Photo here:

San Francisco Trams etc

The trolleybus system lasts there because of some extreme gradients in the city, which are beyond the abilities of diesel buses, especially when loaded. It was the same for the cablecars, which initially lasted, until they became a feature in their own right, because of some of the steep hills...

www.railforums.co.uk

 

[Roger1973]

We discussed a while ago that Cincinnati in the USA long had this dual wire arrangement for streetcars, due to concerns about earthing issues, and a photo showed that at changeover to trolleybuses these used the same wires. Photo here:

Thanks - don't think I saw that thread. And didn't know that.

A bit of further research came up with Havana, Cuba (website 'Tramway of Cuba' has photos) and Merrill, Wisconsin (photo as part of this page on Trainweb) as places that also used twin wires for trams.

 

[Beebman]

Tokyo used to have twin wires, this page has some photos from the 1910s:

https://www.oldtokyo.com/tokyo-streetcars-tokyo-toden-c-1910-1920/

 

[Vespa]

Tokyo used to have twin wires, this page has some photos from the 1910s:

https://www.oldtokyo.com/tokyo-streetcars-tokyo-toden-c-1910-1920/

I suspect Tokyo did that because of the frequent earthquake split tracks will cause earthing issues, wires flex more and won't snap, fixing tracks is hard enough without the need to make sure tracks are bonded to earth.

 

[341o2]

The place I recall reading about this (trolleybus running with one pole on tram overhead, with skate/trolley trailer for current return to tramtrack) being done was in Birmingham, to enable trolleybuses on one of their routes to access the depot, which was down a tram route from the trolleybus route.

That would have been the isolated Nechells route, which was withdrawn when WW2 was declared, as it was feared that sparks from the skate bouncing along tram tracks would provide a target for German bombers

 

[Whisky Papa]

Apologies if this is deemed O/T as it is something new rather than historical, but the two new trolleybus routes in Prague share road space with existing tram routes at some points, but don't share wiring. The 58 at Palmovka runs in a one-way loop inside the footprint of the tram lines (which cross at 90 degrees here) so doesn't need to cross their wiring. It does run parallel to it for a short distance heading northbound, sharing stops with the tram.

However, at the Nádraží Veleslavín terminus of bus 119 to the airport, the as-yet unused new trolleybus wiring crosses the tram overhead at 90 degrees in the central reservation of Evropská as it leaves the terminus. Further west at the rebuilt Divoká Šárka stop, the trolleybus wiring moves into the central reservation so as to share the tram stop, but again is simply parallel to the tram wiring. I'm not sure when this is due to start operation, or whether it will keep the same number.

​

 

[Taunton]

Running both trolleys and trams along the same street, separate wires, is more straightforward if the trams have trolley poles, the insulators needed where the wires cross are short. If the trams have pantographs however the wires have to be kept much further apart, and insulators and complexity where they cross are more of an issue, to avoid the tram pantograph short-circuiting the trolleybus wires.

This one in St Petersburg, Russia, with a tram Grand Union (all-ways junction) and trolleybus wires through the middle of it, is an absolute cat's cradle. Photo here:

https://www.google.com/maps/@60.003...e0!5s20170801T000000!7i13312!8i6656?entry=ttu

I believe when Helsinki, Finland had trolleybuses the trams had to pull down their pantographs when crossing the wires. They also had simplistic automatic point controls on the tram wires where the driver had to identify which way the points lay, and pull the pantograph down if they didn't want them changed.

 

[Ken H]

Running both trolleys and trams along the same street, separate wires, is more straightforward if the trams have trolley poles, the insulators needed where the wires cross are short. If the trams have pantographs however the wires have to be kept much further apart, and insulators and complexity where they cross are more of an issue, to avoid the tram pantograph short-circuiting the trolleybus wires.

This one in St Petersburg, Russia, with a tram Grand Union (all-ways junction) and trolleybus wires through the middle of it, is an absolute cat's cradle. Photo here:

https://www.google.com/maps/@60.003...e0!5s20170801T000000!7i13312!8i6656?entry=ttu

I believe when Helsinki, Finland had trolleybuses the trams had to pull down their pantographs when crossing the wires. They also had simplistic automatic point controls on the tram wires where the driver had to identify which way the points lay, and pull the pantograph down if they didn't want them changed.

UK trams set the points by taking power of going on the main route and shutting off power to take a turnout. This system was also used to set the 'points' in the overhead for trolleybuses. (I think UK trolleybus men call the 'points' 'frogs')

 

[Whisky Papa]

Running both trolleys and trams along the same street, separate wires, is more straightforward if the trams have trolley poles, the insulators needed where the wires cross are short. If the trams have pantographs however the wires have to be kept much further apart, and insulators and complexity where they cross are more of an issue, to avoid the tram pantograph short-circuiting the trolleybus wires.

This one in St Petersburg, Russia, with a tram Grand Union (all-ways junction) and trolleybus wires through the middle of it, is an absolute cat's cradle. Photo here:

https://www.google.com/maps/@60.003...e0!5s20170801T000000!7i13312!8i6656?entry=ttu

I believe when Helsinki, Finland had trolleybuses the trams had to pull down their pantographs when crossing the wires. They also had simplistic automatic point controls on the tram wires where the driver had to identify which way the points lay, and pull the pantograph down if they didn't want them changed.

Yes, the trolley wires are well offset to clear the pantographs. I did manage to take a photo of a tram going under the 90 degree crossing of the new trolleybus wires at Nádraží Veleslavín but would have to check how to post it on here. There is a quite substantial piece of metalwork at the crossing point. It seems slightly odd to go to this complexity, as both trolleybus routes will use battery power over quite significant parts of their length anyway.

 

[Richard Scott]

Geneva has trolleybuses and trams along same route and they all use separate wires; makes for some interesting arrangements at junctions!

 

[jp4712]

Manchester made a point of separating tram and trolleybus overhead, as you can see on this archive photo.
Manchester tram 960 at London Road station by Museum of Transport Greater Manchester, on Flickr

 

[Buzby]

Glasgow Corporation Transport (GCT) operated both a tram and Trolleybus services in the city, but from memory (they ceased when I was in my early teens). they never ‘shared’ routes - the trams had single wire bow collectors, whilst the buses made use of twin swivel trolley wheels - when they crossed you could see the arcing at night!

 

[Vespa]

UK trams set the points by taking power of going on the main route and shutting off power to take a turnout. This system was also used to set the 'points' in the overhead for trolleybuses. (I think UK trolleybus men call the 'points' 'frogs')

I've driven trolleybuses at Sandtoft there is a trigger frog with a light, to operate it you had pedal down 3 notches and pull the handbrake on, the surge will fire the frog and a yellow light will tell you that the frog has been set, it's an art to release the handbrake and pedal at the same time without shooting forward.

 

[Taunton]

UK trams set the points by taking power of going on the main route and shutting off power to take a turnout. This system was also used to set the 'points' in the overhead for trolleybuses. (I think UK trolleybus men call the 'points' 'frogs')

Other way round actually, power for the turnout and coast for straight ahead. This might sound counter-intuitive but is appropriate when you think about it, the vehicle turning will slow right down and then give some power through the overhead switch. A timing relay will only set for the turnout if power is drawn through the switch for say two seconds or more, say not more than 5mph, so if a straight ahead vehicle inadvertently goes through at speed with the power on the points will not be set to divert it. A further relay on the branch, immediately beyond the turnout, sets it back to the straight again.

The difficult situation is if a straight ahead vehicle is in a traffic jam and crawling along, it must not take any power through the relay switch. Marks for the driver in the roadway normally assist with this, otherwise it's stop and out with the point iron ...

 

[Buzby]

I never knew points could be automated in such a way for trams, I had only ever seen the driver leave the cab with a metal bar to flip the frog in the desired direction of travel. There was a small signal on a nearby lamppost at the junction which consisted on 6 small white bulbs in a ‘V’ formation (3 on each). It remained lit 24x7 showing which leg of the divergence was set, giving advance notice of whether there would be a need to change it.

 

[Taunton]

I never knew points could be automates in such a way for trams, I had only ever seen the driver leave the cab with a metal bar to flip the frog in the desired direction of travel.

Such was available more than 100 years ago. Two manufacturers were Charles Hadfield and Collins, both I think from Sheffield. When I was in Hong Hong, the old traditional tramway still there from the British era had automated points with Hadfield stamped on the cover plates, although the business is long gone.

Edinburgh on their old system apparently had an even more sophisticated approach at the key complex junction at the East End of Princes Street, with a control box on the pavement, actually just a cabinet with switches, electric points, and a "signalman" there all day to switch vehicles as required. I think there were once a couple of these elsewhere around the country.

Last ditch is indeed for the driver to have to stop, get out with the point iron, and move the points from being set the wrong way, sometimes accompanied by some un-Parliamentary expression that might be audible from the front seats ...

 

[Beebman]

I was in Melbourne, Australia a year ago when a route had to be diverted due to an accident and a member of staff was braving the traffic to manually move a rarely-used point with a metal rod.

 

[Strathclyder]

Glasgow Corporation Transport (GCT) operated both a tram and Trolleybus services in the city, but from memory (they ceased when I was in my early teens). they never ‘shared’ routes - the trams had single wire bow collectors, whilst the buses made use of twin swivel trolley wheels - when they crossed you could see the arcing at night!

This is something I've never been 100% sure on myself.

Most of Glasgow's trolleybus routes directly replaced tram routes, but sections of route did overlap, mostly in the city centre and of course at major junctions (George Square, Gorbals Cross, Bridgeton Cross, Cowcaddens etc). In photographs of the Glasgow trollies with tram tracks visible, it's often quite hard, if not impossible, to tell if there's collector wires for the trams above it, but this image is perhaps the best I've yet found, from the excellent page on the trollies on the Glasgow History blog.

 

[Buzby]

The tram routes were extensive, but it would be stretching it to say the Trolleybus replaced them like-for-like. I have a very old GCT map showing this area A there was only 1 east-west route and ran Shielhall to Rutherglen 101, 106, 108 the rest were mainly cross river using Stockwell. Saltmarket and Kings Drive bridges. As I recall the major junctions were along Norfolk Street as the buses heading to/from the north side crossed it at right angles.

The 107 had a loop at Maitland Street (Cowcaddens) where it joined the main drag up Garscube Road, this area had much tram activity too but I cannot recall the layout!

 

[Busaholic]

Geneva has trolleybuses and trams along same route and they all use separate wires; makes for some interesting arrangements at junctions!

Was watching a 'touristy' video on YouTube last night set in Zurich and noticed articulated trams and trolleybuses using the same street but wasn't looking closely enough to ascertain how they managed it.