Safety Factors The raised tread on patented TARCA track is 1/8" thick (20% of the 5/8" rail thickness) and 1/4" on patented SUPER TARCA track (25% of the 1" rail thickness).  Although the raised tread adds some strength, patented TARCA track load carrying capacity calculations do not include the raised tread wear tread depth. Benefits: Assures substantially longer service life Capacity unaffected by tread wear Safety factor of 5 unaffected by tread wear Limitations of Competitive Track: Since most other patented track has virtually no raised tread, the intial load carrying capacity is in the total cross section.  The same is true for I-beam track.  As a result, as soon as any wear of the tread occurs for other patented track or I-beams, load carrying capacity is reduced.  The factor of safety falls below the recommended minimum of 5.