Concrete Tie Degradation Study Tie Condition and Crack Growth Rate - - PowerPoint PPT Presentation

▶
concrete tie degradation study
SMART_READER_LITE
LIVE PREVIEW

Concrete Tie Degradation Study Tie Condition and Crack Growth Rate - - PowerPoint PPT Presentation

Aug 28, 2022 224 likes •451 views

Concrete Tie Degradation Study Tie Condition and Crack Growth Rate Assessment Final Results Funded By Federal Railroad Administration Office of Research and Development Under Broad Agency Announcement BAA-2010-1 June 5, 2014 Presented by:

slide-1
SLIDE 1

Federal Railroad Administration Office of Research and Development

Concrete Tie Degradation Study

Tie Condition and Crack Growth Rate Assessment Final Results Funded By Federal Railroad Administration Office of Research and Development Under Broad Agency Announcement BAA-2010-1

June 5, 2014 Presented by: Jeff Henderson ENSCO, Inc.

slide-2
SLIDE 2

Federal Railroad Administration Office of Research and Development

Study Overview

  • Main Objective

Using machine vision technology, develop a better understanding of concrete tie degradation

  • Project Team

– FRA Office of Research and Development – AMTRAK – ENSCO

Sponsored by the Federal Railroad Administration under BAA-2010-1

slide-3
SLIDE 3

Federal Railroad Administration Office of Research and Development

Technical Approach Overview

1) Image 100 miles of track 3 times over ~1-year 2) Use software to manually align track bed images 3) Grade ties and determine crack growth rates 4) Assess concrete tie degradation over time

slide-4
SLIDE 4

Federal Railroad Administration Office of Research and Development

Technology Used

Hi-rail-based Machine Vision Imaging System

  • High Data Rate Line Scan Machine Vision Cameras
  • High Data Rate Solid State Hard Drives
  • High-intensity LED Lighting
slide-5
SLIDE 5

Federal Railroad Administration Office of Research and Development

Track Number Mile Post Start Mile Post End Total Miles 1 187 158 29 1 218 189 29 2 143 158 15 2 187 159 28 2 189 218 29 Total Number of Miles 130

Test Zone Location

(Amtrak’s AB Line, Northeast Corridor)

slide-6
SLIDE 6

Federal Railroad Administration Office of Research and Development

Summary of Test Schedule

  • Survey 1 – August 16 to 19, 2012
  • Survey 2 – April 15 to 19, 2013
  • Survey 3 –September 23 to 25, 2013
slide-7
SLIDE 7

Federal Railroad Administration Office of Research and Development

Concrete Tie Degradation Study

Summary of Analysis Approaches

Subjective Analysis

  • Assess general tie conditions
  • Evaluate tie degradation based on tie grades
  • Grading scale: 1-good to 5-ineffective
  • Assess a large population of ties ~26,000

Objective Analysis

  • Use machine vision images to measure crack area
  • Derive growth rate from measured crack area
  • Conduct parametric analysis of crack growth rates
  • From track charts: Speed, Grade, Curvature,
  • From other sources: Manufacturer, Crack Size, and

Crack Location

slide-8
SLIDE 8

Federal Railroad Administration Office of Research and Development

Tie Condition Analysis

Types of Conditions Observed

Cracking Crumbling Erosion Missing Fastener Chipping

slide-9
SLIDE 9

Federal Railroad Administration Office of Research and Development

Tie Grading Approach

Use software to visually review and grade tie images

Grade 1 – Good Tie Grade 3 Grade 2 Grade 4 Grade 5 – Ineffective Tie

slide-10
SLIDE 10

Federal Railroad Administration Office of Research and Development

Crack Growth Rate Determination

Use Software to Measure Crack Growth Rate

Unannotated Crack Survey 1 Annotation Survey 3 Annotation

Δ Area = 7 mm2 Area 1 = 928 mm2 Area 2 = 935 mm2 Growth Rate = 6.5 mm2 /yr Annualize the result:

slide-11
SLIDE 11

Federal Railroad Administration Office of Research and Development

Parametric Analysis Approach

Use Statistics to Assess Growth Rates Across Multiple Crack Populations

0% 20% 40% 60% 80% 100% 120%

0.00 0.03 0.05 0.08 0.10 0.13 0.15 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51 54 57 60 63 66 69 72 75 78 81 84 87 90 93 96 99 More

Cumulative Frequency Normalized Frequency

Annualized Growth Rate (mm^2/yr)

Frequency distributioin Cumulative percent curve

  • Cumulative percentage is the integral (running total) of normalized frequency
  • Combines crack growth rate within a population of cracks into a single curve
  • Provides a means of quantifying crack growth rate over a population of cracks
slide-12
SLIDE 12

Federal Railroad Administration Office of Research and Development

Tie Condition Results

Distribution of Tie Grades

Grade 1 Grade 2 Grade 3 Grade 4 Grade 5

Grade 1 – 97% Grade 2 – 2% Grade 3 – 0.8% Grade 4 – 0.2% Grade 5 – 0.2%

  • Distribution based on ~26,000 ties
  • Typical tie age 33 years

12

slide-13
SLIDE 13

Federal Railroad Administration Office of Research and Development 13

Tie Condition Results

Distribution of Condition Types

46% 44% 4% 6%

Crack Chip Missing Fastener Crumbling

slide-14
SLIDE 14

Federal Railroad Administration Office of Research and Development

Tie Condition Results

Percent Change in Number of Tie Grades Over One Year

  • Most ties did not

advance in grade

  • Most ties that did

advance in grade did so by 1 grade level

  • Relatively few ties

advanced by 2 grade levels

  • No ties advanced by

more than 2 grade levels

  • 0.23%

0.22% 0.01% 0.00% 0.00% 0.0%

  • 6.5%

6.2% 0.3% 0.0% 0.0% 0.0%

  • 3.8%

3.0% 0.8% 0.0% 0.0% 0.0%

  • 5.8%

5.8% Grade 1 Grade 2 Grade 3 Grade 4 Grade 5 Grade 1 Grade 2 Grade 3 Grade 4 55 Ties 3 Ties 32 Ties 2 Ties 6 Ties 2 Ties 3 Ties 58 Ties 34 Ties 8 Ties

slide-15
SLIDE 15

Federal Railroad Administration Office of Research and Development

Crack Growth Rates for Total Assessed Crack Population

50% 60% 70% 80% 90% 100% 10 20 30 40 50 60 70 80 90 100 110 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 More Cumulative Percentage

Frequency Annualized Crack Growth Rate ( mm^2/year)

1386 Measured Growth Rate Half Normal Distribution Cauchy Distribution Cumulative Percentage

  • Number of cracks assessed: 2139
  • Number that did not grow: 1386
  • Number that grew: 748
  • Median growth rate: 6.5 mm2/year
slide-16
SLIDE 16

Federal Railroad Administration Office of Research and Development

Parametric Analysis Results

Parameters that Influenced Crack Growth Rate

Parameter Growth Rate of a Typical Crack (mm2/Yr) Growth Rate Spread (mm2/Yr) 2-Sigma Uncertainty (mm2/Yr) Residual (mm2/Yr) Combined Factors Worst case Best case 13 3.8 9.2 2.4 6.8 Crack Size Small crack Medium crack Large crack 4 8.3 7.9 4.3 2.0 2.3 Field VS Gauge Gauge side Field side 8.9 5 3.9 2.1 1.8 Curvature Non-tangent track Tangent track 8.9 5.3 3.6 2.1 1.5 Tie Manufacturer Manufacturer “B” Manufacturer “A” 8.1 5.9 2.2 2.1 0.1

slide-17
SLIDE 17

Federal Railroad Administration Office of Research and Development

Parametric Analysis Results

Parameters that did not Influence Crack Growth Rate

Parameter Growth Rate of a Typical Crack (mm2/Yr) Growth Rate Spread (mm2/Yr) 2-Sigma Uncertainty (mm2/Yr) Residual (mm2/Yr) Posted Speed High range (130 - 150 mph) Low range (30 - 125 mph) 6.5 6 0.5 2.0

  • 1.5

Grade Neutral Grade (|Grade|≤ .116) Non-neutral Grade (|Grade|> .116) 6.4 6.2 0.2 1.9

  • 1.7
slide-18
SLIDE 18

Federal Railroad Administration Office of Research and Development

Impact of Measurement Uncertainty

0.00 0.20 0.40 0.60 0.80 1.00 1.20 1 2 3 4 5 6

Standard Deviation of Median RSS Measurement Uncertainty

slide-19
SLIDE 19

Federal Railroad Administration Office of Research and Development

Tie Manufacturer Comparison

0.0% 0.2% 0.4% 0.6% 0.8% 1.0% 1.2% 1.4% 1.6% 1.8% 2.0% 2.2%

  • 52
  • 48
  • 44
  • 40
  • 36
  • 32
  • 28
  • 24
  • 20
  • 16
  • 12
  • 8
  • 4

4 8 12 16 20 24 28 32 36 40 44 48 52

Percentage of Cracked Ties Approximate Distance from Tie Ceter (inches) Manufacturer "A" Manufacturer "B"

slide-20
SLIDE 20

Federal Railroad Administration Office of Research and Development

Conclusions

  • The observed crack growth rates were not alarming (median

growth rate = 6.5 mm2/year

  • Tie grades progressed at a non-alarming rate
  • Curvature, crack size, crack location (field or gauge side of the

tie), and tie manufacturer had a statistically significant impact

  • n crack growth rates
  • Posted speed (track class) and track grade (the degree of

incline) did not have a statistically significant impact on crack growth rates

  • Tie manufacturer and/or manufacturing lot appears to play an

important role in crack prevalence

slide-21
SLIDE 21

Federal Railroad Administration Office of Research and Development

Remaining Unknowns

  • The progression rate of failure modes other than cracks (e.g.,

crumbling and chipping)

  • The impact of tonnage on crack growth rates
  • The impact of seasonal variations on crack growth rates
  • The impact of different geographical regions on tie

degradation

  • Potential variations among additional tie manufacturers
slide-22
SLIDE 22

Federal Railroad Administration Office of Research and Development

Acknowledgements

Federal Railroad Administration Office of Research and Development

  • Mr. Hugh Thompson – FRA Project Manager
  • Mr. Cameron Stuart – BAA Program Manager

National Railroad Passenger Corporation (Amtrak)

  • Mr. Mike Trosino
  • Mr. Steven Sawadasavi
  • Mr. Joe Mascara

Computer Vision Laboratory at the University of Maryland, College Park

  • Professor Rama Chellapa
  • Mr. Xavier Gibert-Serra