Gauge Strength Measurement

    Holland's TrackSTAR® testing vehicles utilize a unique Split Load-Axle system which applies constant and consistent vertical and lateral loading to the rails during testing. The patented TrackSTAR® test vehicles measure track gauge twice; first unloaded gauge is measured at the front of the test vehicle, and second, loaded gauge is measured at the load axle near the middle of the vehicle. The on-board computers align the two gauge measurements in the data set and the difference between the two gauges, delta gauge, is used as a key input to determining the reserve gauge strength of the track to dynamic loadings. The on-board strip charts and exception reports provide immediate feedback showing where cross-ties or fasteners are weak.

    The split-axle loading applied to the rail heads is approximately 15,000 pounds vertical and 10,000 pounds lateral, delivering an L/V ratio of approximately 0.65. This non-destructive load is monitored by Holland's patented Axle Performance Evaluation System (APES), which assures consistent gauge strength testing to industry and FRA standards. APES also provides feedback to Holland's operators evaluating the performance and maintenance requirements of the load-axle, maintaining high-quality measurement of the track strength.

    Gauge Strength Testing is "performance-based" measurement of the condition of the cross-ties and fastening system. As such, it is not influenced by what cross-ties/fasteners look like--but rather provides objective and accurate information on how cross-ties/fasteners are performing under load. Gauge Strength Testing can be used to enhance the process of selecting the specific ties that need to be replaced, improving the effectiveness of maintenance work, improving safety, improving the overall performance of track, and potentially saving limited budget money.

Benefits of Gauge Strength Testing:

•  Performance-based, objective measurement of reserve gauge strength
•  Minimizes the need for walking inspection and visual tie-defect identification
•  Locates weak gauge strength conditions that can affect safe movement of trains
•  Pro-active management tool and tie planning process
•  Identifies clusters of weak ties or broken fasteners
  
•  Long term planning tool
•  Enables track maintenance supervisors to build a business case for tie programs
•  Enables track maintenance supervisors to establish annual tie budgets
  
•  Derailment prevention
•  Spot maintenance indication / prioritization

GRMS (Gauge Restraint Measurement System)

    Over the past 20 years the FRA, AAR, AREMA, and various other companies including Holland® have been developing GRMS standards and methods to provide improved tools for railway owners. In April of 2002, the FRA adopted minimum safety standards as it relates to the use of GRMS evaluation and inspection of track. Section 213.110 of the Track Safety Standards (TSS) provides for waiver of Sections 213.9 and 213.27 inspection requirements for cross-ties and fasteners. The addition of the GRMS alternative standard option to the TSS was one of the most significant changes to the standards in decades, and recognizes the importance and value of measuring reserve strength of track objectively. The 213.110 standards outline the requirements for GRMS testing, including the use of exception thresholds for Loaded Gauge, GWR (Gauge Widening Ratio), and PLG (Projected Loaded Gauge).

• Loaded Gauge - The measurement of gauge at the load axle under defined vertical and lateral loading.
• GWR (Gauge Widening Ratio) - The normalization of delta gauge to a 16,000 lb lateral load. (GWR is currently under review by the FRA Safety on the basis of recommendation by FRA Research to replace with GWP, Gauge Widening Projection.)
• GWP (Gauge Widening Projection) - A measurement of reserve gauge strength to defined vertical and lateral loading. A 1.00" GWP as measured by TrackSTAR® is confirmed in the field by a delta gauge of 0.625" with a PTLF (Portable Track Loading Fixture) of 4,000 lb. lateral.
• PLG (Projected Loaded Gauge) - A projection of what gauge would be under an extreme loading condition of 24,000L/32,000V.

Holland's TrackSTAR® system has been evaluated by FRA and found to be acceptable for use as a "GRMS standard" testing vehicle.

Additional GRMS and Gauge Strength Information

The performance-based objective gauge strength and GRMS data can be effectively used to support other analyses of track including:

• Cross-tie statistics and summary reports based on selectable thresholds
• Cross-tie replacement budget development
• Post-process visual tie planning, allowing tie budgets to be overlayed on the track geometry strip charts

(click to view larger version)

In October 2006, the magazine Railway Track and Structures wrote an article detailing the history of GRMS testing in the US and the evolution of FRA standards relating to GRMS.