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What can happen at a tram/rail crossing

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What can happen at a tram/rail crossing

Unread postby Andrew Waugh » Wed Apr 1, 2015 3:11 am

What you don't need at the tail end of peak hour... Fortunately, it doesn't appear anyone was hurt.

http://pic.twitter.com/aQqOScpLk3

Locally, catch points are being removed from tram/rail level crossings - this might be the last set left - and you can see why. The catch points certainly derailed the tram. But this made the magnetic track brakes useless. Despite its disc brakes, the tram ran up a slight incline, completely cleared two rail tracks and stopped over a third. The catch points also aimed the tram at the footpath and buildings. It was fortunate that the righthand wheel appears to have turned the leading bogie when going over the crossing so that the tram ended up parallel to the track.

My son and I spent an enjoyable half hour or so watching how they rerailed the tram. The recovery team were very professional.
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Re: What can happen at a tram/rail crossing

Unread postby JG Morgan » Wed Apr 1, 2015 5:24 am

Andrew Waugh wrote:My son and I spent an enjoyable half hour or so watching how they rerailed the tram. The recovery team were very professional.


Where is this? obviously not in this country:
(a) impossible in half an hour
(b) you would not have been allowed anywhere near to watch
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Re: What can happen at a tram/rail crossing

Unread postby AN106 » Wed Apr 1, 2015 6:35 am

Blowing up the image, and with a bit of Googling, I think it's Glenhuntly Station on the Melbourne Tram network, Australia. This is the end of the line, which makes me wonder if these are genuine trap points, or redundant points for a former (or future) loop.
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Re: What can happen at a tram/rail crossing

Unread postby John Hinson » Wed Apr 1, 2015 7:38 am

I would be surprised if you are wrong about the location.

However, I doubt a loop would be planned there because the trackwork would be unnecessarily complex crossing two three railway lines. That being said, a few more moves like that and the trams would create a track of their own!

I don't question Andrew's words, re-railment would be hasty given that tram, railway and road are all blocked. Nor is there much that can be done to prevent people watching, it is a busy public road.

As to the question of the need for traps, that is a grand example of traps provided as a matter of principle and not practicality. The same could be said (and has been before) of British traps in sidings (etc) protecting running lines which may well stop an escapee but do not necessarily prevent the line from being blocked. Here the tram has managed to cross two of the railways lines and stop (it appears) across the third. We do not know the circumstances that caused this, of course.

So should one let a tram such as this risk collision with trains if it fails to stop or should more drastic measures be provided? Food for thought, and probably something the Australian Authorities are already considering.

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Re: What can happen at a tram/rail crossing

Unread postby Andrew Waugh » Wed Apr 1, 2015 10:33 am

Sorry. Yes, indeed, it is Glenhuntly in Melbourne, Australia.

This is one of four remaining tram/train crossings in the Melbourne system. The others are Kooyong, Gardiner, and Riversdale. All have local gate boxes supervising the crossing. Glenhuntly is a panel, the other three have mechanical frames. A photo of the Glenhuntly panel by Chris Gordon can be found here: http://vicsig.net/index.php?page=infrastructure&box=Glenhuntly

The catch points are indeed intended to protect the train lines from wayward trams. Until recently the provision of catch points in the tram lines at these crossings was standard practice. However, in the couple of years the catch points at Gardiner and Kooyong have been removed, and I think those at Riversdale have also gone. I was told the reason for this was that the modern trams depend heavily on magnetic track brakes (i.e. a shoe that is forced down on the rail by a big electromagnet), and when derailed these brakes, of course, become useless. As you can see from the photo, in this case the catch points spectacularly failed to stop the derailed tram before fouling the train line - the tram rolled over a double track crossing, about 20 feet of road, and finally stopped straddling the third track. It may well have stopped sooner had it remained on the track.

As John says, I expect to eventually see an official report from the (Victorian) Office of the Chief Inspector of Transport Safety. I will note a couple of things: the flange marks suggest that the catch points were open when the tram went through them. The boom barriers were intact which indicates that they were up.

It took about half an hour to actually rerail the tram, but this might give a misleading impression. Before that there was a period of an hour or so while the crews were notified, the investigation presumably occurred, and they set up. There was also an hour or so afterwards before services recommenced while the overhead and track was checked. Digressing from strict signalling, the rerailing was very interesting. Motive power was by a massive recovery truck which was coupled to the front of the tram. It was used to pull the tram forward. Steering the bogies was by a big dished plate. Think of half a wok, but in much thicker metal. This was carefully (and precisely) placed in front of the leading wheel with the dish upwards. The tram was then pulled forward, and the bogie turned slightly as the wheel ran over the plate. A second set of plates was used on the other side to allow the flanged wheel to run across the rail without dropping into the flangeway. As I said, it didn't take very long at all.
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Re: What can happen at a tram/rail crossing

Unread postby AN106 » Wed Apr 1, 2015 10:52 am

John Hinson wrote:However, I doubt a loop would be planned there because the trackwork would be unnecessarily complex crossing two three railway lines.


Oops - I was so busy studying the station name, I didn't spot the transverse tracks! :oops:
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Re: What can happen at a tram/rail crossing

Unread postby Andrew Waugh » Wed Apr 1, 2015 11:04 am

Oh, and I meant to comment on John's comment on more drastic measures.

The original tram/train crossings in Melbourne were with cable trams. Melbourne had one of the largest cable tram networks in the world - I think it was the largest operated by a single organisation, and it lasted intact until the '20s. There were a couple of locations where cable tram lines crossed train lines. By the end, there was none of this namby pamby catch points. Protection was by a massive bolt that physically obstructed the cable slot. If a tram grip hit the bolt it would bring the tram to a sudden stop, break the grip, and do the same to the cable.

There was a reason for this brutal approach. As the cable wore, the outer strands would break. This was normal and processes were in place to manage this. However, it was possible for the broken wire to become entangled in a grip. Then there was a problem. This would mean the cable tram could not stop - in those days there was no quick way for the tram crew to notify the power house to stop winding. Telephones were placed every quarter or half mile or so - but by the time the tram passed one, the conductor got off, made contact, and the message was acted on, the tram could have run for a mile or so. Hence the physical barrier at a railway crossing.

Victoria also had locations where horse trams crossed train lines. (Curiously, Glenhuntly was one of these.) Nothing special was done at these locations beyond the usual interlocked or hand gates. No catch, or signal. Presumably horses were considered unlikely to run through the heavy wooden gates.

When electric trams began to be installed, the first instance of a train crossing was in Ballarat. Again, no catch or signal was provided (or, indeed, ever provided). A little later on, when electric trams began to be provided in Melbourne, the standard provision became catch points in track, disc signal, and interlocked gates. This seems to have been quite effective. However, there was one crossing (over a minor steam operated passenger carrying branch) which had no protection what-so-ever. No gates, no signals, and no catch points. At this location the electric trams were supposed to stop and be hand signalled across the crossing by the conductor. There was at least one collision at this crossing.
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Re: What can happen at a tram/rail crossing

Unread postby Stuart Johnson » Wed Apr 1, 2015 11:18 am

JG Morgan wrote:
Andrew Waugh wrote:My son and I spent an enjoyable half hour or so watching how they rerailed the tram. The recovery team were very professional.


Where is this? obviously not in this country:
(a) impossible in half an hour
(b) you would not have been allowed anywhere near to watch


In the UK we haven't got the wondrous device that Andrew mentions to rerail trams, but TfL's Emergency Response Unit have certainly carried out their work under the close scrutiny of the general public. In this incident the tram was outside East Croydon station, and the public who were leaning on the waist-high barriers around the site gave the recovery crew a round of applause when they dropped the last wheels back on! Needless to say, the crew took a bow...
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Re: What can happen at a tram/rail crossing

Unread postby Mike Hodgson » Wed Apr 1, 2015 11:56 am

Better it happens at the tail of the peak hour than at the start!

This incident doesn't in itself invalidate the case for traps though. It merely reinforces the point that they should be so placed as to divert offending trams away from the hazard you are trying to protect. This one looks far to close to the railway lines to be effective, even the basic design looks like it goes back to the days of horse trams.

Plenty here for the investigating authorities to consider. As the barriers were apparently up, they will need to ascertain whether the trap blades were incorrectly open whilst the crossing was open for trams or whether the tram had managed to cross during the brief interval between initiation of the crossing sequence but before the barriers moved.

If the former is the case, the obvious question is what safeguards exist to ensure the railway does not clear signals following the incident ; if the latter, the reason for the trap being open needs explanation - do they have some form of FPL? Either way, the suitability of this trap design is questionable - perhaps such traps also need a steel plate in the roadway beyond the trap if reliance is placed on electromagnetic brakes?

Fortunately the tram has gone so far that it has not completely blocked the railway, there is certainly a case for the policy of letting a tram run unimpeded in the hope that it will clear the crossing before the arrival of a train. This could obviously have been a nasty incident, not just for people on train or tram, but it also looks like a high risk of taking pedestrians unaware too.
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Re: What can happen at a tram/rail crossing

Unread postby John Hinson » Wed Apr 1, 2015 12:33 pm

Mike Hodgson wrote:Plenty here for the investigating authorities to consider. As the barriers were apparently up, they will need to ascertain whether the trap blades were incorrectly open whilst the crossing was open for trams or whether the tram had managed to cross during the brief interval between initiation of the crossing sequence but before the barriers moved.

Yes there is, but we are too un-informed to know the circumstances and cause.

Mike Hodgson wrote:Fortunately the tram has gone so far that it has not completely blocked the railway, there is certainly a case for the policy of letting a tram run unimpeded in the hope that it will clear the crossing before the arrival of a train. This could obviously have been a nasty incident, not just for people on train or tram, but it also looks like a high risk of taking pedestrians unaware too.

To my eyes, it actually stopped across the third of the three railway lines.

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Re: What can happen at a tram/rail crossing

Unread postby Andrew Waugh » Thu Apr 2, 2015 12:30 am

Couple of comments...

John is correct - the derailed tram stopped squarely on the third track.

The comment about catch points and derailing to a safe location is, of course, the key. The question is where would that be? The tram rolled for such a long way, that any direction would appear to be unsafe. Parallel to the tram track means the level crossing is fouled. Away from the tram track means that the tram will enter the footpaths (possible running over pedestrians) and hitting buildings.

For those that are interested, here is a precise of the operating instructions from 1997 (I don't believe they have changed since). Note that the levers (9 & 10) operating the tramway catch points also operate the tramway signals (this matches the former mechanical practice). There is approach locking on the catch points, with a manual override.

Upon the approach of an Up or Down train, the Signaller must check that Tramway Signals 9 and 10 are at Stop. The Signaller must then restore Boom/Overhead lever 7 to normal and operate Pedestrian Gate levers 11/12 as required. Operation of lever 7 will cause the boom barriers to lower and the overhead power to be switched to the rail. The Signaller must check that the booms are down (indicated by a green light on lever 7) and the ‘Rail’ indicator is shown before clearing the Home signal.

When the last vehicle of the train has cleared the section insulator, electric locking on lever 7 will be free and allow the lever to be reversed. This will switch the tramway power supply to the square and cause the booms to rise. The Signaller must ensure that the ‘Tram’ indicator is showing before clearing the tramway signals.

The tramway catch points (9 and 10) are motor operated. Skates are attached to the tramway overhead to detect the approach of a tram. If a tram is on the approach to either Tramway Signal 9 or 10 and the lever is restored to normal, the signal will return to Stop but power is removed from the catch points. In this case the Signaller must first check that the tram has not passed the tramway signal. If the tram has stopped behind the tramway signal, the Signaller must operate either 9 or 10 emergency 5P keyswitch for one second. This will restore power to the catch points and they will run to the derail position.

The Power/Manual switch for the Tramway Catch points is only to be placed in the Manual position when the Catch points do not obey the lever, the 5P emergency release has failed to operate, and only in the presence of an authorised tramway official. The official will operate the points and must remain until the fault is rectified.

If the overhead power fails to switch, the Signaller must operate the emergency 5P keyswitch for one second. This will operate the motor driven overhead switch. The Signaller must observe the Rail/Tram indicator to ensure the correct indication is displayed. Emergency manual operation of the overhead power switch is also provided. The overhead power switch (Rail Tram Activator Switch) is located in a cabinet adjacent to the Down Main Line. An operating crank attached to an 11P key is kept in a keyswitch in the cabinet. To manually operate the overhead power, the key is turned to the reverse (2 o’clock) position and removed. The crank may then be used to manually wind the operating switch to the desired position. ‘Rail’ and ‘Tram’ indicators are provided in the cabinet to indicate when the switch has been fully operated.

If the boom barriers fail down, the Signaller must manually raise the barriers, check that the overhead is switched to tram power, and check that the catch points are closed before verbally authorising the tram to pass the tram signals. If the overhead cannot be switched to tram power, the tram driver must coast over the crossing with trolley pole or pantograph lowered.

If the boom barriers fail to operate, the Signaller must check that the tramway signals are at Stop and that the overhead power is set for Rail operation. A Signallers Caution order must then be completed and handed to the Driver. The Driver must be cautioned to proceed cautiously as the boom barriers will not operate until the leading wheels of the train have passed the Home signal.
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Re: What can happen at a tram/rail crossing

Unread postby John Webb » Thu Apr 2, 2015 8:27 am

Thanks to Andrew for the detailed explanation above. The provision of catch-points at this location seems to introduce a lot of complexity, as does the need for switching the overhead from one traction supply to another.

I have done some studying of UK trams - the last London trams ran from my part of SE London and I recall being taken for a last ride on the trams during their final week of service - and I don't remember any mention of catch points at all. There were a number of places where trams crossed the railway - but in the London area I don't think there were any crossings of two overhead line equipment systems, although there may have been elsewhere in the country. I assume recent tram installations specifically try and avoid such complexity, particularly in view of the considerable differences in voltage of the two systems.
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Re: What can happen at a tram/rail crossing

Unread postby JRB » Thu Apr 2, 2015 2:45 pm

Do they switch overheads there? A common arrangement is a dead section over the crossing.
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Re: What can happen at a tram/rail crossing

Unread postby edwin_m » Thu Apr 2, 2015 7:36 pm

Certainly there are no tram-rail crossings of any type in the UK at present and given the rarity of railway electrification in the heyday of the tram I very much doubt there would ever have been tram crossings of British electrified railways. However there may well be some on the Continent although I haven't seen any myself.

If a reliable arresting of the tram was required then one possibility might be to direct the trap point into an area of frangible thin concrete covering a shallow pit filled with loose material. If the tram overran the end of the trap the wheel flanges would break this concrete and it would sink in, being brought to a halt by the drag and possibly also the friction if the underside of the tram grounded on the edge of the pit - effectively the tram equivalent of a sand drag. This is used on the dead end tracks of Manchester Metrolink. It might be necessary to locate it out of the traffic lanes, since the covering would probably not survive long if run over by heavy road vehicles.
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Re: What can happen at a tram/rail crossing

Unread postby JRB » Thu Apr 2, 2015 7:50 pm

There are several tram/train crossings on mainland Europe with 2 voltages. Most of the Dutch ones have gone, but there were some in Delft which used the dead section procedure.

GB tram train crossings usually (a requirement?) had trap points. I remember them being still visible on Gloucester Barton St. drawings and the levers re-used for traffic light interlocks.
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