Safety Issues Investigation Report SII R05-01

3.0 Findings

1. The statistical analysis demonstrates that annual bulk tonnage traffic is strongly correlated with the rail defect rate at a statistically significant level, while overall tonnage is not.

2. Where rail weight is less than 130 pounds, increased bulk unit train tonnage significantly increases rail defects, resulting in a higher risk of broken rail derailments.

3. Although railways recognize the accelerated rate of track degradation associated with bulk unit train tonnage on secondary main lines, the occurrence record indicates that an appropriate balance between increased track degradation and timely infrastructure maintenance and/or renewal has not been achieved.

4. Although railways are responsible for putting measures in place to keep the track safe and in compliance with the Railway Track Safety Rules (TSR), the TSR may be insufficient to ensure safety because they do not consider the adverse effects of overall increased traffic and specifically bulk unit train tonnage on secondary or feeder track systems over the long term.

5. Inadequately inspected and maintained rail joints represent a critical point of vulnerability since they are prone to defect development and failure. Inspections of rail joints using current rail defect detection equipment or geometry cars are unable to identify joint bar defects.

6. There is a continuing risk of fatigue cracking around rail bolt holes because chamfering of field drilled holes is not carried out.

7. While rail defect testing reduces the risk of broken rail derailments, the detection of all internal rail defects is not within the capacity of the defect testing methods currently in use.

This report concludes the Transportation Safety Board's investigation into this occurrence. Consequently, the Board authorized the release of this report on 25 May 2006.