The content of this help page provides the basis for the calculation of the default model activity-specific life cycles. Users considering overriding life cycles calculated by the model may find it helpful to first review this framework.

The overarching equations used to calculate the activity-specific life cycles are summarized in the table below.

 

Individual life cycle factors referenced in the table are calculated as shown in the following tables, with the specific calculated factors shown being for default model inputs.

Speed Factor

Grade Factor

Wheel Load Factor

Curve Factor

Rail Factor Rail

Wood Fastener Factor Rail

Rail Factor Surface

Rail Factor Tie

 

Undercutting Factor

Ballast Depth Factor

Wood Tie MGT Factor

Wood Tie Climate Factor

Wood Fastener Factor Tires

Wood Fastener Factor Surface

Concrete Tie Factor

Grinding Factor

Alternate Tie Life Factor

 

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