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What happened

At about 1404 on 14 May 2014, the fourth wagon from the end of train 3WB3 derailed whilst exiting the Nambucca Heads crossing loop. The train travelled a further 1,397 m before the derailed wagon tipped on its side causing the train to separate and subsequently stop.

What the ATSB found

The ATSB found that the rod-in-coil load had likely shifted, mostly to the left in the direction of travel. The effect of a load shift to the left would have been to transfer vertical forces from the wagon’s right side-bearer to the left side-bearer, causing the right-hand wheels to unload.

At the point of derailment, the track geometry was transitioning out of a left-hand curve which had a relatively high superelevation with respect to the actual speed of train 3WB3 (about 21 km/h). The relatively high superelevation and subsequent twist as the superelevation ramped down through the transition, likely resulted in additional transfer of vertical force from the wagon’s right side-bearer to the left side-bearer, resulting in a further unloading of the right-hand wheels.

The combination of superelevation, twist and (more importantly) uneven lateral loading, combined to unload the right-hand wheels which, when steering through a left-hand curve, resulted in flange climb and derailment of wagon RCOF20375S.

What's been done as a result

Following the occurrence, Pacific National Assets and Infrastructure Services engaged a consultant to conduct an audit of procedures and operational processes relating to the development and implementation of the Freight Loading Manual (FLM). The audit was scoped specifically to include a gap analysis in relation to current steel loading processes.

In addition, PN have advised that they will be arranging an external engineering group to undertake a twist test and/or computer simulation modelling of an RCOF wagon to record its wheel loading performance characteristics during scenarios based on operational data. It is expected that the outcomes of this work will be used to further refine the FLM and associated procedures and loading practices.

Safety message

The ability for a load to shift during transit is an undesirable condition that can affect the dynamic behaviour of the rail vehicle. All rail freight operators should consider the safety implications of shifting/moving loads and should ensure that all loads are restrained and/or enclosed in such a way that prevents movement in any direction relative to the wagon.

 

 

 

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The occurrence

Context

Safety analysis

Findings

Safety issues and actions

Sources and submissions

 
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Preliminary report released 12 September 2014

The occurrence

At 1355[1] on 14 May 2014, freight train 3WB3 entered the Nambucca Heads crossing loop. The route was set for a through movement via the loop because of trackside work being performed adjacent to the main line.

At 1404:20, the trailing wheel set of the leading bogie on wagon RCOF20375S derailed to the right-hand-side in the direction of travel while the train was travelling through the crossing loop at a speed of 21 km/h. The derailed wagon was located fourth from last in the 44 wagon consist.

The train continued to travel with a derailed wagon for about 1,397 m. It passed over two bridges and reached a speed of 44 km/h before wagon RCOF20375S tipped on its side (Figure 1). The train then parted between the fourth and fifth last wagons. As the wagons parted, the train brake pipe separated, allowing air to vent to atmosphere and the train brakes to apply, bringing the train to a stop in about 320 m.

The train crew notified the network controller and arrangements were made to begin investigative and restoration work. The main line was subsequently reopened at 1816 on 16 May. The crossing loop line remained closed until further repairs could be conducted.

Figure 1: Derailed wagon RCOF20375S

 RO2014007_Fig1
Source: ATSB

Context

The location

Nambucca Heads is located on the main north rail corridor between Sydney and Brisbane, about 565 track kilometres from Sydney Central Station. Nambucca Heads is a crossing location with a 1,615 m crossing loop.

Track information

The ARTC manages the railway corridor where the derailment occurred. Authorised movement of rail traffic is controlled from the ARTC’s Network Control Centre located at Broadmeadow, New South Wales.

The standard gauge[2] track at the derailment location consisted of 53 kg/m rail fastened by resilient clips to timber sleepers, spaced at about 667 mm centres. The sleepers were supported on a bed of ballast to a nominal design depth of 250 mm.

Approaching from the southern end, the track through the derailment site consisted of a series of curves between 480 m and 360 m radii on reasonably level track. The posted maximum track speed was 75 km/h although this speed would rarely be reached, due to the restriction of speed through the points.

On-site examination and preliminary analysis of track condition found no indication of any serious anomalies in the track geometry leading up to the point of derailment in the crossing loop.

Train information

Train 3WB3 was a steel products freight service operated by Pacific National between Wollongong and Brisbane. At the time of the derailment, the train consisted of two locomotives (NR94 leading and AN9 trailing) hauling 44 freight wagons. It was 817 m in length and had a trailing mass of 3,363 t.

The train was operated by two qualified drivers. They had both been assessed as fit for duty in accordance with the requirements of the National Standard for Health Assessment of Rail Safety Workers.

RCOF wagons are 15.1 m long and capable of carrying up to 80 gross tonnes at speeds of up to 80 km/h (depending on track speed limits). On the day of the derailment, wagon RCOF20375S (the wagon which derailed) was carrying 40 coils of rod, each weighing on average 1.5 t. The coils were arranged, two wide by two high, in each of the 10 bays (Figure 2). The coils were contained within the wagon, but they were not individually restrained.

On-site inspection and preliminary examination of the derailed wagons found no indication of any serious anomalies in rolling stock condition. Similarly, preliminary analysis of train data indicated that there were no anomalies in the train speed, train handling or operational performance leading up to the derailment.

However, evidence of load shifting had been observed in wagons not affected by the derailment, but carrying the same rod-in-coil product.

Figure 2: Loaded RCOF wagon on train 3WB3 carrying rod-in-coil product

 RO2014007_Fig2
Source: ATSB.

Ongoing investigation activities

The ATSB’s investigation is continuing and will focus on:

  • the integrity of the rolling stock involved
  • the possibility of load shifting en route
  • the policies and procedures relating the securing of loads
  • the integrity of the track structure


[1]    The 24 hour clock is used in this report. Local time was Australian Eastern Standard Time (EST).

[2]     The name given to gauge of  track of 1435mm

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Safety issue

RO-2014-007-SI-01 -  

Loading rules and procedures

The Pacific National freight loading manual, and application of it, was ineffective at preventing load
shift with rod-in-coil product.

Safety issue details
Issue number:RO-2014-007-SI-01
Who it affects:All transporters of rod-in-coil product
Status:Safety action pending

 
General details
Date: 14 May 2014 Investigation status: Completed 
Time: 14054 EST Investigation type: Occurrence Investigation 
Location   (show map):Nambucca Heads  
State: New South Wales  
Release date: 23 September 2015 Occurrence category: Accident 
Report status: Final Highest injury level: None 
 
Train details
Line operator: ARTC 
Train operator: Pacific National 
Train registration: 3WB3 
Type of operation: Freight 
Sector: Freight 
Damage to train: Serious 
Departure point:Woollongong, NSW
Destination:Brisbane, Qld
 
 
 
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Last update 23 December 2016