Concrete Tie Insulator Performance

Transcription

1 Concrete Tie Insulator Performance Eric Gehringer Director of Track Maintenance AREMA

2 Agenda Concrete tie strategy Objectives of research Histogram of insulator design Terminology Failure mechanisms & implications Laboratory tests In-track testing Tiered insulator standards Concrete Tie Strategy Challenging topography Steep grades Tight curvature Heavy axle load territory Red-X Risk Mitigation Major metropolitan areas Protected Habitats Economics Tandem replacement of ties & rail assets New Construction / High Speed Rail Red X Concrete Ties 8.2 million 3,24 miles Indianapolis, 8/2/1 IN Objectives Concrete Tie Insulators Establish systematic insulator sampling and inspection protocol to facilitate effective annual capital allocation renewal programs Quantify insulator post wear rate as a function of accumulated tonnage and track geometry Quantify field versus gage side insulator post wear rates Quantify insulator post wear rate for specific general model types Establish product specific in-track life cycles Validate laboratory testing with active in-track testing AREMA Chp. 3, Section Insulators Insulation shall be used where necessary to prevent interference with signal systems and deterioration of the fastening system through electrical leakage. Insulation may be provided by insulators placed at appropriate locations in the fastening assembly or by other acceptable means. AREMA Chp. 3, Section Concrete Ties Insulators are typically used for setting and maintaining gage on concrete tie tracks. AREMA Chp, 3, Section Comments Insulators: Insulator post wear has a direct influence on the rate of rail seat abrasion and premature pad failure. Insulator design should consider environmental and loading factors. Histogram of Insulator Usage Concrete tie insulators first introduced on the Union Pacific Railroad in Continuous lab research and field testing has resulted in major insulator design revisions over the past 25 years that include: Material types (plastic, bronze, etc.) Moisture content (varied from 1.2%-3%) Material hardness Post width (4.5 mm 11.5 mm) Material inserts (cast iron, abraded surface, etc.) In total, 29 insulator designs have been utilized in the past 25 years with varying intrack performance that until recently had not been quantified. Terminology Insulator post width - (4.5 mm 11.5 mm) Seated insulator post Insulator Post Improperly Seated Post 984 AREMA 213

3 Terminology Insulator fastener load bearing designs standard, light duty and heavy duty Insulator Failure Mode Repeated wheel loadings force material to compress and expand causing abrasion to the post that is further exacerbated by longitudinal rail movement caused by thermal expansion of the rail. In extreme instances the base of the rail contacts the shoulder due to the insulator being displaced or the post being worn through. Light Duty - Steel Heavy Duty Cast Iron Bronze Objective: Establish systematic insulator sampling and inspection protocol to facilitate effective annual capital allocation renewal programs Since 211, Union Pacific Railroad has collected, inspected and measured 2,8 insulators. 1 9 Objective: Establish systematic insulator sampling and inspection protocol to facilitate effective annual capital allocation renewal programs Insulator Sample Data Accumulated Tonnage & Degree of Curvature Tangent 1-3 deg. 4-6 deg. 7-9 deg. > 1 deg. Accumulated Tonnage < 25 MGT 25 MGT - 5 MGT 5 MGT-1 BGT > 1 BGT Objective: Quantify insulator post wear rate as a function of accumulated tonnage and track geometry Insulator post wear versus degree of curvature is relatively linear (R 2 value of.7) Slight variations in wear rate/1 MGT accumulated versus degree of curvature attributed to small sample size (<2 units) for 3, 7 and 9 degree curves. Objective: Quantify field versus gage side insulator post wear rates Average of 3:1 ratio of field insulator post wear rate vs. gage insulator post wear rate. Wear rate ratio permits the reuse of gage side insulators during rail renewal or maintenance operations..2 Gage R² = Tangent 1-3 deg. 4-6 deg. 7-9 deg. > 1 deg..2. Tangent 1-3 deg. 4-6 deg. 7-9 deg. > 1 deg. AREMA

4 Objective: Quantify insulator post wear rate for specific general model types. Superior wear rates for cast bronze and heavy duty cast insert designs Inferior wear rates for insulator with no insert and light duty steel insert designs Cast Bronze Post, Heavy Duty Cast Post, Light Duty Steel Post, No Cast Objective (cont.): Quantify insulator post wear rate for specific general model types. Insulator wear rate/1 MGT for wide post designs is exponentially higher than average of standard post designs Disparity between standard versus wide post insulators stems from concrete tie shoulder wear. Results in non-uniform force distribution exerted on the load bearing area of insulator post increasing the propensity for vertical and longitudinal movement Cast Bronze Post, Post, Post, No Wide Post, Heavy Heavy Duty Cast Light Duty Steel Cast Duty Cast Wide Post, Light Duty Steel Objective: Quantify product specific replacement cycles Significant in-track performance variations between insulator designs. Designs with superior performance incorporate heavy duty cast inserts or cast bronze material. 6 Objective: Quantify insulator post wear rate as a function of accumulated tonnage and track geometry Insulator life cycles versus degree of curvature is moderately linear (R 2 value of.6) Moderate variation in insulator life cycle trend stems from varying supplier and design specific in-track performance Wide Post, Light Duty Steel Post, No Cast Wide Post, Post, Light Post, Heavy Heavy Duty Cast Bronze Duty Steel Duty Cast Cast Product Life Cycle (tonnage) R² =.5857 Total Tangent 1-3 deg. 4-6 deg. 7-9 deg. > 1 deg. Objective: Establish product specific in-track life cycles Significant variations in in-track performance between model groups and suppliers Objective (cont.): Establish product specific in-track life cycles Significant variations in in-track performance between model groups and suppliers X X X X X X X HD-1 Product Life Cycle (tonnage) X X X X X X X X HD P38165 Post, No Cast Post, Light Post, Duty Steel Heavy Duty Cast Wide Post, Light Duty Steel Wide Post, Heavy Duty Cast Post, No Cast Post, Light Duty Steel Post, Heavy Duty Cast Wide Post, Light Duty Steel Wide Post, Heavy Duty Cast Cast Bronze 986 AREMA 213

5 In-Track Test Locations In-Track Test Locations - Mojave Sub MP MP Deg. Of Total Ties Fastener Side Insulator Gage Side Insulator Mojave Safelok I Heavy Duty Std Post Bronze Tie Armor Heavy Duty Std Post Safelok III & V Post Post In-Track Test Locations - Canyon Sub MP MP Deg. Of Total Ties Canyon Fastener Safelok I Safelok III & V ) Side Insulator Heavy Duty Std Post SF I Bronze (Bronze) SF III Bronze Heavy Duty Std Post Heavy Duty Std Post SF I Bronze (Bronze) Gage Side Insulator Post Post In-Track Testing Results of research: Baseline geometry vehicle base gage data recorded for Mojave, Canyon, Evanston and Little Rock subs in late 212. Run over run geometry vehicle base gage data to be collected and analyzed in DEC 213-MAR 214. Final in-track testing results to validate laboratory testing and further improve insulator wear rates as a function of track geometry, elevation and location in curves (i.e. spiral or body). Base Gage (in.) Moffat Tunnel Base Gauge MP to MP Product X Base Gage Delta After 73 MGT Base Gauge 21 Base Gauge 212 Delta Base Gauge 5 per. Mov. Avg. (Delta Base Gauge) Tiered s Improving life cycles requires the establishment of operating environment specific life cycles of existing and future standards: Sampling In-track testing Laboratory testing (MTS) Theoretical testing (FEA) Data based maintenance and capital renewal intervals improves safety by managing corridor/sub risk profiles Results Insulator performance has gradually improved over past twenty years Design revisions focused on increasing insulator foot print on rail base and increased material thickness Insulator post wear versus degree of curvature is relatively linear (R 2 value of.7) Insulator life cycles versus degree of curvature is moderately linear (R 2 value of.6) Average of 3:1 ratio of field insulator post wear rate vs. gage insulator post wear rate. Wear rate ratio permits the reuse of gage side insulators during rail renewal or maintenance operations Inferior wear rates for insulator with no insert and light duty steel insert designs Designs with superior performance incorporate heavy duty cast inserts or cast bronze material Insulator wear rate/1 MGT for wide post designs is exponentially higher than average of standard post designs Significant variations in in-track performance between similar model groups from different suppliers AREMA

6 Results Establishing tiered standards requires railroad specific analysis based on product unit costs, annual insulator replacement demand, curve density, etc. Design specific insulator product life cycles presented can be utilized in basic financial analysis to determine optimum tiered standard for a specific operating conditions. QUESTIONS? Tiered Option #1 Tangent: standard insulator with no cast insert 1-6 degree curves: heavy duty insulator with cast insert >6 degree curves: bronze insulator Tiered Option #2 Tangent: standard insulator with no cast insert s: bronze insulators 988 AREMA 213