Atsb transport Safety Report



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Organisation


Queensland Rail provides suburban commuter rail services on the City network, covering Brisbane, Ipswich and the Sunshine and Gold Coasts. Queensland Rail also provides long distance passenger services to other major centres in Queensland. The Cleveland rail line is part of the Queensland Rail city network with passenger services at about 30 minute intervals during week days shortening to about 15 minute intervals during the peak period.

Infrastructure

Track


The track structure between Ormiston and Cleveland stations consisted of 50 kg/m rail fastened to concrete sleepers laid on a bed of hard rock ballast. The track approaching Cleveland station had a falling grade8 of 1:130 from about the Wellington Street overbridge to just before the turnout, where the track grade transitioned to level into the station platform.

Inspections following the collision showed no evidence of obvious track defects or misalignments. The track geometry measurement car run carried out in September 2012 found the track to be within tolerances and of sound alignment.

The rail along this section was in good condition with some side wear on the high leg of the curve on the approach into Cleveland station. Rail lubricant residue was obvious on the bottom of the gauge face of this rail indicating the rail lubrication of this length of track9 was being maintained. There was no evidence of rail lubricant on the head (top) of the rail. The rail wear was within limits.

The rail on curves is generally ground every two years and this track section was last ground in June 2012. The rail on the tangent (or straight) track had not been included in the rail grinding cycles. This track carries around 8 million tonnes of traffic per year consisting of light axle load vehicles and there was no evidence of distress or damage on the rail head. The rail wheel contact patch was narrow and centred, indicating that rail grinding was not necessary.

There were two turnouts on the approach to Cleveland station, 650A and 650B. Turnout 650A divided the single track approaching the station into the two platforms and was a 1 in 12, 60 kg, fixed heel switch, with a rail bound manganese (RBM) crossing. This turnout was fixed to concrete bearers and had resilient clips fastening the rail to the sleepers. The turnout was observed to be in very good condition. Turnout 650B was on the approach to Cleveland station platform 2 and provided access to a storage road. Turnout 650B was identical to 650A and was found to be in a similar condition.

Overhead traction system


The overhead traction power equipment is the structures and overhead equipment necessary for the supply of traction power to electric trains. Queensland Rail trains operate on a 25 kV AC traction system. Trains collect power through a pantograph when in contact with the single overhead contact wire that is supported by catenary wires cantilevered from trackside masts.

During the collision, car 5173 rode up and over the buffer stop and then collided with the end of line overhead power catenary pole located behind the buffer stop. The force of the impact collapsed the pole, dislodging the catenary wires and tensioning equipment as the train continued to travel towards the platform end and station buildings.


Buffer stop


A buffer stop is a structure located at the end of a railway track section and is designed to prevent a train travelling beyond defined limits, such as railway station terminals. The buffer stop should include features to limit injuries to train drivers, passengers and the public and to minimise damage to rolling stock, buildings and other infrastructure. Energy absorbing and rigid buffer stops are the two most common types used by railways in Australia.

The purpose of an energy absorbing buffer stop is to progressively transform a train’s residual kinetic energy into heat through friction elements that move together with the buffer stop frame along the track or through the displacement of hydraulic rams or springs.

The rigid buffer stop was the first type to be used on railway systems and generally consists of a frame or block rigidly fixed to the rails or in the ground. A rigid buffer stop has a limited ability to dissipate a train’s kinetic energy and is generally only effective in low speed collisions, nominally 5 km/h or less. Rigid buffer stops were installed at the Cleveland station.

Buffer stop design


A buffer stop’s capacity to stop a train is determined according to the train’s maximum weight and speed. When designing buffer stops a standard method is to base calculations on a passenger train travelling between 10 km/h and 15 km/h. For example, for the design of buffer stops on terminal tracks, German passenger train operator Deutsche Bahn uses a collision speed of 10 km/h in their calculations.

The Queensland Rail’s South East Queensland Network (SEQN) has a total of seven buffer stops located on running lines at Cleveland, Domestic Airport, Varsity Lakes and Nambour railway stations.

The buffer stops located at the end of the island platform tracks at Cleveland station are rigid reinforced concrete structures with rubber fenders (Figure ). The buffer stop was constructed of a 2.9 m high concrete block protruding vertically 1.7 m from the ground and attached to a pair of horizontally reinforced concrete beams extending about 5.5 m under each rail.

Figure : Design of buffer stops installed at Cleveland station



figure 5: design of buffer stops installed at cleveland stationSource: Queensland Rail Limited – Chief Civil Engineers Branch

A rubber fender is attached to the concrete block that also has a contact plate matching the profile of the City Train coupler. Design drawing notes showed the buffer stops at Cleveland station were calculated to arrest a train with a maximum mass of 200 t at a maximum impact speed of 5 km/h. The leading edge of each buffer stop was located about 15 m beyond the train stopping point and the end of the station platform. There was no track laid behind the buffer stop and there was a further 5 m between the buffer stop and the Cleveland station building foundation and pavement that arose about 800 mm above ground level (Figure ).

Train T842 weighed about 256 t and was travelling at about 31 km/h when it collided with the buffer stop. The impact force significantly exceeded the design capability of the concrete buffer stop which was unable to dissipate the train’s energy and so failed. This allowed the train to continue into the Cleveland station building.



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