October 17 , 2006
Home Valley, Washington
April 3, 2005
The animation is available in Flash format and was presented at the Board Meeting on 10/17/2006 in Washington, D.C.
This animation contains audio.
This three dimensional animation graphically demonstrates the railroad track features in the accident of Amtrak Train Number 27, which derailed on the BNSF Railway Company's Northwest Division on April 3, 2005. This animation is for representational purposes only. It is not to scale, and does not depict weather or visibility conditions at the time of the accident.
Script:
This animation graphically demonstrates track features in the accident derailment.
In 1990, the BNSF installed concrete crossties in this area.
The investigation found 19 crossties with varying degrees of rail seat abrasion in the immediate area of the derailment.
Many of the tie pads in the area had worn out or been displaced since their installation.
Let's look at the effects of crosstie abrasion in more detail.
When tie pads are no longer effective, the cement surface of the crosstie is repeatedly abraded by the flexing of the rail under load.
As the abrasion of the rail seat increases in depth, an angled void is created under the rail base.
The worst abrasion measured 1 1/4 inches in depth.
This allows the railhead to rotate outward and widen the gage, which is the distance between the rails.
It was at this location where the train derailed.
In this accident the rail seat abrasion became excessive and the gage widened so much that a wheel on the inside of the curve dropped within the gage of the track, which began the derailment sequence.
