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Tx dot use of pfc Tx dot use of pfc Presentation Transcript

  • TxDOT’s Use of Permeable Friction Courses (PFC) Arkansas Asphalt Pavement Association January 6, 2006 Dale Rand, P.E. TxDOT Construction Division Flexible Pavements Branch
  • TxDOT’s Mission Statement The mission of the Texas Department of Transportation is to provide safe, effective and efficient movement of people and goods. TxDOT’s Vision Statement The vision of the Texas Department ofTransportation is to provide transportation systemsand alternatives that are comfortable, safe, durable, cost-effective, accessible, environmentally sensitive and aesthetically appealing.
  • TxDOT HMA Classifications, 2004 Standard Specifications• Item 340 Dense Graded Hot Mix Asphalt (Method)• Item 341 Dense Graded Hot Mix Asphalt (QC/QA)• Item 342 Permeable Friction Course (PFC)• Item 344 Performance Design Mixtures• Item 346 Stone Matrix Asphalt (SMA) View slide
  • Type “D” Hot MixPFC View slide
  • Why does TxDOT’s like SMA & PFC Stone Matrix Asphalt (SMA)…..Durability High binder content and stone matrix offer the best combination of cracking and rutting resistance relative to other known mixes Permeable Friction Course (PFC)….Safety Reduces risk of hydroplaning Significantly reduces splash and spray Improves visibility of traffic markings Quieter than most other options Improved ride quality
  • BackgroundTxDOT used OGFC (plant mix seal) up until the early1990sTxDOT ceased using OGFC in the early 90s due todurability issuesTxDOT started using PFC in 2000The use of PFC is growing at a steady rateThere are approximately 100 PFC projects completedor currently under construction in Texas
  • Comparison of Plant Mix Seal and Permeable Friction Course Characteristic Plant Mix Seal Permeable Friction Course Binder Grade AC-10 PG 76-22 AC-10 (+ 3% latex) Asphalt Rubber (A-R) Binder % 5 – 7% 6 – 7 % (PG 76) 8 – 10% (A-R) Fiber N/A 0.3 % Cellulose or Mineral Cantabro Loss N/A, > 30 % < 20% Permeability Moderate High Air Voids 12% – 15% 18% - 22% Production 212F – 220F 300F – 350F Temperature Not all moisture removed Removes all moisture Drain down 0.5 – 1.5% 0.0 Typical 0.3% MaximumTypical thickness 1.0 inch or less 1.25 to 1.5 inches Typical life 5 – 8 years 10 – 14 years
  • OGFC – Gradation Comparison (% Passing) Sieve Texas Texas Georgia Georgia ODOT Texas Size Grade 1 Grade 2 1/2 inch 1/2 inch OGFC 1/2 inch Plant Mix Plant Mix Modified PEM PFC Seal Seal OGFC PG761/2 inch 95-100 95-100 85-100 90-100 100 80-1003/8 inch 50-80 50-80 55-75 35-60 90-100 35-60 #4 0-8 5-20 15-25 10-25 25-40 1-20 #8 N/A N/A 5-10 5-10 N/A 1-10 #10 0-4 5-15 N/A N/A 0-10 N/A #200 N/A N/A 2-4 1-4 0-5 1-4
  • Master Gradation Band (% Passing by Weight or Volume) and Binder Content Sieve Size PG 76 Mixtures A-R Mixtures 3/4" 100.0 100.0 1/2" 80.0 – 100.0 95.0 – 100.0 3/8" 35.0 – 60.0 50.0 – 80.0 #4 1.0 – 20.0 0.0 – 8.0 #8 1.0 – 10.0 0.0 – 4.0 #200 1.0 – 4.0 0.0 – 4.0 Binder Content, % 5.5 – 7.0 8.0 – 10.0
  • @ 9 years - AsphaltRubber - PFCLufkin District
  • ComfortRide quality Noise
  • US 287 (Wichita Falls District) International Roughness Index (IRI) Comparison of 2 Projects Completed in the Fall of 2001 140 120 Avg. IRI = 90 100IRI (In./mi.) 80 60 US 70/ US 287 Avg. IRI = 43 0472 +01.2 to 0478 +00.2 40 US 287 0300 +00.5 to 0312 +00.0 20 0 Reference Markers Flexible (PFC + Superpave) Rigid (11" CRCP)
  • % Energy Loss -Vs- dBA Reduction 98 98.4 98.75 99 97.5 100 94 95 96 97 92 90 90 85% 85 88 80 80 75% Sound Energy Loss 70 70 60 60 50 50 40 37 30 20 20 10 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Noise Reduction (dBA)
  • Highway SafetyFor most people, driving is the most dangerousactivity that we are ever involved withBy 1950, more Americans were killed in autoaccidents then were killed in both world warsA high percentage of accidents happen inintersections and in horizontal or vertical curvesWet weather accidents account for a highpercentage of highway fatalities
  • How Can PFC Mixes Improve Safety? Reduces the risk of hydroplaning Drains the water off the roadway quicker Reduces spray Reduces glare Improves visibility of traffic markings Coarse macro-texture improves frictional characteristicsQuestion: Can we prove that these things actually reduce the occurrence of wet weather accidents?
  • IH 35 – San AntonioPFC Overlay on Existing CRCP
  • A-R PFC on CRCPIH 35 San Antonio, Fall 2002
  • IH 35 – San AntonioA-R PFC Overlay on Existing CRCPExisting concrete pavement– Relatively sound structurally (Durable)– Approximately 20 years old (Durable)– History of numerous wet weather accidents (Safety?)– Ride Quality was poor (IRI = 200) (Comfort?)– Considered to be one of the loudest pavement surfaces around (Comfort?)
  • A-R PFC Overlay on CRCP IH 35 San Antonio1.5 inches of A-R PFC– Improved the ride quality of the existing CRCP by approximately 61%– Improved the skid resistance by over 200%– Reduced the noise level by an average of 8 to 14 decibels (measured by 3 different individuals)– Significant reduction in major accidents after the PFC overlay
  • Climatic & Accident Data IH 35 San Antonio: Before and After A-R PFC OverlayJuly 2001-June 2002 Nov 2003-Oct 2003• Total Precipitation: • Total Precipitation: – 31.78 inches – 32.63 inches• Total Days with… • Total Days with… – Measurable precipitation: 69 – Measurable precipitation: 99• Major Accidents: 85 • Major Accidents: 48• Major Accidents on Days • Major Accidents on Days with Precipitation: 39 with Precipitation: 19 Climate data obtained from National Oceanographic and Atmospheric Administration
  • PFC Mix US 183 – Williamson Co. South Bound near San Gabriel River Click on image below to show videoDense Grade (Type C)
  • Dense Grade Click on image below to show video PFC Mix RM 1431 – Travis County WBL – Between Cedar Park and Jonestown
  • RM 1431 – Travis County – Pictures from Feb 14, 20042001 – 2003: 124 Total Accidents2001 – 2003: 68 Wet Weather Accidents2001 – 2003: 6 Fatalities, 62 Injuries (13 incapacitating)Note: Project length is only 2 miles long
  • Accident Data: FM 1431 - Travis County - Near Jonestown (PFC mixture was placed in February 2004) Averages % ChangeYear 2001 2002 2003 2004 2001-2003 in 2004Total # of accidents 29 51 44 17 41.3 -58.9Dry weather accidents 10 23 13 15 15.3 -2.2Wet weather accidents 19 28 21 2 22.7 -91.2Fatalities 0 1 5 0 2.0 -100.0Total injuries 25 16 21 0 20.7 -100.0Incapacitating injuries* 6 4 3 0 4.3 -100.0Non-incapacitating injuries 19 12 18 0 16.3 -100.0Annual rainfall (inches) 42.9 36.0 21.4 52.0 33.4 55.5Total rain days (>0.1 in.) 57 56 37 70 50.0 40.0* Some of these injuries later became fatalitiesSource: Cedar Park Police Department
  • Safety is a Major Quality of Life Issue
  • ConclusionsTxDOT uses a variety of 4 different HMAmixturesGoal: Select the most appropriate mixture typefor each given applicationThe use of PFC and SMA is increasing inTexas due to the unique properties of thesemixesPFC is considered to be the quietest and safestoption currently available for paving
  • Thank You Texas Departmentof Transportation