XPT Derailment

 
  Valvegear Dr Beeching

Location: Norda Fittazroy
How many years is it since railways were invented?

Apparently not enough for our hick systems to have learnt anything.  For months, we have been unable to run a comparitively small train into the second-biggest city in Australia. The level of incompetence is mind boggling.

Sponsored advertisement

  JimYarin Chief Commissioner

Location: Adelaide, South Australia
confused.  is the report saying the track was wrong or was it the wheel profile on the xpt?
  richter170 Locomotive Driver

I believe that the turnout was made up of incorrect parts which didn't accept all wheel profiles. Both of them have been replaced by new turnouts with longer blades from what I understand.

The train wheels were not a contributing factor in the derailment.

The only advice was to regularly check flanges are within tolerance.

Al.
  kuldalai Chief Commissioner

Even as a preliminaryvreport these things are written in a convoluted language after comments from all parties involved. , so as to keep everyone happy. The report clearly says that the wheel profiles and treads of both Vlp and XPT stock were within tolerances for operation over sg and dual gauge trackage. generally and meets Australian Standards.
The report clearly says the dg turnouts were tested with sg rollingstock, but not XPT stock prior to commissioning .
Coming to the specific dual gauge turnout design used on the flyover :

A photograph within the report shows clearly that where a sg narrow profile XPT wheel transfers from a sg rail to bg rail that a sg xpt wheelset is out of gauge and the wheel will fall into the four foot.

So by inference the turnout design is the problem in that a wide profile sg wheel as on vlp and gsr carriages will negotiate the specific turnout design as intended. However the thinner profile XPT wheel and this type of turnout present an issue with transfer of the sg wheel through the turnout.

Thus the current focus to 1.  to alert all rail operators to the potential of derailment with thin profile sg wheels through specific design types of dg turnouts. and 2. the modification of the track componentry within the offending dg turnout type to allow for the passage of sg wheelsets of all types.

One should be very careful of being critical here of any party as dual gauge trackage especially turnouts and crossovers, gauge splitters are very complex engineering designs.  The report indicates clearly that all parties including VLP have been pro active in identifying the issue, correcting it and learning from it .
  Valvegear Dr Beeching

Location: Norda Fittazroy
One should be very careful of being critical here of any party as dual gauge trackage especially turnouts and crossovers, gauge splitters are very complex engineering designs.
kuldalai

Codswallop - absolute codswallop; obviously written by someone who knows very little about engineering - "complex" my foot!
  YM-Mundrabilla Minister for Railways

Location: Mundrabilla but I'd rather be in Narvik
Seems pretty clear that someone has boobed. The XPT wheels were within the standard for wheels so the track should have been designed to cater for them.
  K-Class Chief Train Controller

Location: Melbourne
Seems pretty clear that someone has boobed. The XPT wheels were within the standard for wheels so the track should have been designed to cater for them.
YM-Mundrabilla

Agreed. Definitely looks like the engineer/s designing the turnout either forgot or did not know that the XPT uses a different wheel standard.

Is there any other rolling stock using the same wheel profile as the XPT?

Matt
  YM-Mundrabilla Minister for Railways

Location: Mundrabilla but I'd rather be in Narvik
Does anyone know why the XPT uses a narrower wheel tread dimension, please? I assume that there is a reason even if it is only because of its Pommie origin
  Heihachi_73 Chief Commissioner

Location: Terminating at Ringwood
It's OO gauge instead of HO. Stupid poms. Laughing
  nscaler69 Deputy Commissioner

Location: There are no stupid questions, but there are a lot of inquisitive idiots.
Nah, sounds more like NEM instead of NMRA standard. Laughing
  historian Deputy Commissioner

Has no one actually read the preliminary report?

The preliminary report clearly fingers a lack of stiffness in the broad gauge point blade. This *is* a design problem, but not one directly related to the XPT rim width. I quote from page 7:

Examination of the lead wheelset/lead bogie of carriage XAM2176 (wheelset with narrowest field edge to flange face distance) confirmed that there was limited rim contact on the rail head through the transfer area. With the left wheel of XAM2176 running on the right edge of the broad gauge switch rail (in the direction of train travel), this would likely have applied high outward torsional loading on the switch blade. In circumstances where the broad gauge switch blade is insufficiently restrained through the transfer area, the switch blade can both roll and flex outward, increasing the likelihood of one or more wheels dropping in between the track and causing the train to derail.


The report states that the design gauge at this point was 1480 mm (the actual gauge was 1486, but the reports suggest that this was caused by the switch blade being permanently bent by the derailment). The maximum gap that could be spanned by the worst XPT wheelset should have been 1503 mm (= 127 mm rim width + 1357 mm back to back wheel + 19 mm minimum flange width). This means that there should have been 23 mm of tread still on the left hand rail.

The narrow width of the XPT treads made it more likely to derail (a 140 mm wheel rim would have 36 mm still on the rail), and increases the eccentricity of the loading on the switch rail. And the risk would be increased with flanges near the condemning width, and narrow back to back measurements.

And, yes, a dual gauge turnout is a complex engineering design. Particularly where you are trying to build a dual gauge turnout with relatively little difference in the two gauges out of relatively heavy rail.
  t_woodroffe Assistant Commissioner

140mm wide wheel treads are a relatively recent adoption, at least as far as diesel electric locomotives and rolling stock are concerned. From introduction to service until the late 1980s 127mm wheel treads were most common. I suspect that the XPT retained 127 mm wide wheel treads to minimise unsprung mass which can become, via P2 force, an issue at higher speed.

TW
  Valvegear Dr Beeching

Location: Norda Fittazroy
I suspect that the XPT retained 127 mm wide wheel treads to minimise unsprung mass which can become, via P2 force, an issue at higher speed.
t_woodroffe

I would certainly agree with this opinion. To put it mildly, unsprung mass is a nuisance at speed. As an example, the use of alloy wheels on competiton cars is a way of keeping unsprung mass as low as possible.
  Campaspe 2 Locomotive Driver

Hello,

I have been told that one of the reasons the XPT has retained 127 mm wide wheels is due to the disc brake rotors being attached to the wheels, rather than being in-board, like the VLocity railcars.

Apparently, it would be a major modification (possibly even impossible) to fit wider wheels with the braking system fitted to the XPT's.

Any feedback on whether I am right or wrong on this would be greatly appreciated.

Also, V/Line adopted the 140 mm wide wheel in the mid-1990's after the Werribee derailment.  I have been told (but again would like any confirmation) that moving from 130 mm to 140 mm wheels essentially fixed any wheel cracking and other wheel failure related issues that V/Line used to previously experience with its locomotive hauled stock.

Regards

Campaspe
  t_woodroffe Assistant Commissioner

The restriction provided by the brake calipers on the XPT may well prevent wider wheel treads. On reflection the XPT has bogie hung traction motors so unsprung mass may not be such an issue. Some recent locomotive deliveries have been restricted to 127 mm wide wheels because of borderline P2 issues but these locomotives have had axle hung traction motors and thus higher unsprung mass.

The issue of wider treads on VLP loco hauled stock was somewhat pre-empted by utilising wider (140mm) treads on locomotives. This was progressed as it mitigated brake blocks running off the edge of the wheel as a consequence of slop in brake hangers. Blocks running off the edge of the wheel is not good with cast iron blocks and is to be avoided at all costs with composition blocks. Cast iron blocks are excellent heat sinks but composition blocks are insulators and can lead to cracking of wheel treads.

TW
  L1150 Assistant Commissioner

Location: Pakenham Vic.
Are we any closer to a resolution to this problem?

A bit over a week and a half ago (on the Friday before the AFL grand final) the +1 and I came back from a brief break in Sydney on the (very well patronised) XPT. When I purchased the tickets a couple of weeks before, I was assured that the problem would be resolved before we traveled. But not very far south of Sydney, the conductor told us of the need to transfer to buses at Broadmeadows, with more frequent announcements once in Victoria. To their credit, the transfer of the passengers to the fleet of buses at Broady went fairly smoothly.Very Happy

Since then I've traveled over the North Melb. flyover on several occasions on the RRL and have seen no evidence of works at the BG/SG divergence.
  MickAdoe Beginner

Location: Bentleigh, Victoria, Australia
Hey all,
          travelling with the family by xpt to Sydney then to Brisbane this friday, Countrylink call centre already rung to advise will be bus from southern cross to broadmeadows. Really!! One turnout can cause so much disruption between two major cities for 3 months in this day and age?? We wanted to take the kids on something they have never experienced before and probably wont again, in Australia at least.
          I know it's only a minor hiccup but would have been nice to leave southern cross by train to start our trip, and even less to say about the Queensland railways and their 4 am arrival into Roma st so the xpt doesn't tie up their precious tracks.
         It doesn't do much to promote interstate rail travel. Any way will post anything interesting we might see.


                                                        Cheers
  The Vinelander Minister for Railways

Location: Ballan, Victoria on the Ballarat RFR Line
Hey all,
travelling with the family by xpt to Sydney then to Brisbane this friday, Countrylink call centre already rung to advise will be bus from southern cross to broadmeadows. Really!! One turnout can cause so much disruption between two major cities for 3 months in this day and age?? We wanted to take the kids on something they have never experienced before and probably wont again, in Australia at least.
I know it's only a minor hiccup but would have been nice to leave southern cross by train to start our trip, and even less to say about the Queensland railways and their 4 am arrival into Roma st so the xpt doesn't tie up their precious tracks.
It doesn't do much to promote interstate rail travel. Any way will post anything interesting we might see.


Cheers
MickAdoe


You can still depart Southern Cross by train as I did with some friends a few weeks ago when we travelled to Wangaratta on the XPT. Travel METRO to Broadmeadows and walk down the subway at the station and the XPT will be waiting on the SG platform.

There's no proper ticket check undertaken until the train has departed Broadmeadows.

Mike.
  ab123 Chief Train Controller

Noted yesterday that the speed restriction appears to have been lifted. Obviously the new set of point installed must have been an improvement.
  L1150 Assistant Commissioner

Location: Pakenham Vic.
Saw a news item on TV last night about a big rally in Sydney for the new Indian PM. The item mentioned that a contingent of Indians traveled to Sydney from Melbourne by train with the train being briefly shown. It looked to me very much like an XPT at Southern Cross. So, does this mean that the issue on the Nth. Melb. flyover has been resolved, and does anyone know how the solution was achieved?Very Happy
  freightgate Minister for Railways

Location: Albury, New South Wales
XPT has been using scs again for approximately a week. Buncam can confirm.
  kuldalai Chief Commissioner

XPT has been using scs again for approximately a week. Buncam can confirm.
freightgate

The turnouts were modified on site with parts of the componentry replaced to ensure that  sg wise  conventional wheel width cars as on VLP and Overland stock, and narrower width profile wheels as used on XPT can both proceed through the transition process within the turnout without risk of derailment .  Read the interim report  (link posted earlier) to understand what was the likely cause of the original XPT derailment .  Final report still to be published.
  donttellmywife Chief Commissioner

Sponsored advertisement

Display from:   

Quick Reply

We've disabled Quick Reply for this thread as it was last updated more than six months ago.