Buckled track at Ararat sent PN wagons off the rails: ATSB

<p>The Australian Transport Safety Bureau (ATSB) has found that the failure to stress-test a section of curved track after tamping work was a significant factor in the derailment of a Pacific National train at Ararat.</p> <p>Two wagons on the freight train derailed on November 28, 2003 after travelling over buckled rail on a curved section of Australian Rail Track Corporation-managed (ARTC) line at Ararat.</p> <p>Investigators found that on November 20 the track where the derailment occurred was tamped &#8211 a process of lifting and relining and ballasting track using dedicated machines &#8211 to remove a slight kink in the line.</p> <p>ATSB concluded that the tamping probably reduced the resistance of the ballast on the track and had "broken the seal" between the track and the ballast holding it in place.</p> <p>This process had also probably lowered the stress-free temperature of the track, meaning track expansion and then buckling could occur at lower temperatures. </p> <p>When a rail buckles, the outside rail (elevated above the inside rail) in a curve is no longer able to compensate for the lateral and vertical forces placed on it.</p> <p>ATSB found that the passage of the Pacific National train progressively worsened the condition of the buckle.</p> <p>The bureau has recommended that ARTC review its track maintenance procedures to ensure that track geometry and stress-free temperatures remain within standards.</p> <p>It also recommended that ARTC review its monitoring of rail-creep &#8211 longitudinal rail movement due to heat and &#47or train movement. </p> <br />