1. 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

2. 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 of
Transportation is to provide transportation systems
and alternatives that are comfortable, safe, durable,
cost-effective, accessible, environmentally
sensitive and aesthetically appealing.

3. 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)

4. Type “D” Hot Mix
PFC

5. 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

6. Background
TxDOT used OGFC (plant mix seal) up until the early
1990s
TxDOT ceased using OGFC in the early 90s due to
durability issues
TxDOT started using PFC in 2000
The use of PFC is growing at a steady rate
There are approximately 100 PFC projects completed
or currently under construction in Texas

7. 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% Maximum
Typical thickness 1.0 inch or less 1.25 to 1.5 inches
Typical life 5 – 8 years 10 – 14 years

8. 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 PG76
1/2 inch 95-100 95-100 85-100 90-100 100 80-100
3/8 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

9. 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

10. @ 9 years - Asphalt
Rubber - PFC
Lufkin District

11. Comfort
Ride quality Noise

12. US 287 (Wichita Falls District)
International Roughness Index (IRI)
Comparison of 2 Projects Completed in the Fall of 2001
140
120
Avg. IRI = 90
100
IRI (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)

13. % 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)

14. Highway Safety
For most people, driving is the most dangerous
activity that we are ever involved with
By 1950, more Americans were killed in auto
accidents then were killed in both world wars
A high percentage of accidents happen in
intersections and in horizontal or vertical curves
Wet weather accidents account for a high
percentage of highway fatalities

15. 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
characteristics
Question: Can we prove that these things actually reduce
the occurrence of wet weather accidents?

16. IH 35 – San Antonio
PFC Overlay on Existing CRCP

17. A-R PFC on CRCP
IH 35 San Antonio, Fall 2002

18. IH 35 – San Antonio
A-R PFC Overlay on Existing CRCP
Existing 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?)

19. A-R PFC Overlay on CRCP
IH 35 San Antonio
1.5 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

20. Climatic & Accident Data
IH 35 San Antonio: Before and After A-R PFC Overlay
July 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

21. PFC Mix US 183 – Williamson Co.
South Bound near San Gabriel River
Click on image below to show video
Dense Grade
(Type C)

22. Dense Grade Click on image below to show video
PFC Mix
RM 1431 – Travis County
WBL – Between Cedar Park and
Jonestown

23. RM 1431 – Travis County – Pictures from Feb 14, 2004
2001 – 2003: 124 Total Accidents
2001 – 2003: 68 Wet Weather Accidents
2001 – 2003: 6 Fatalities, 62 Injuries (13 incapacitating)
Note: Project length is only 2 miles long

24. Accident Data: FM 1431 - Travis County - Near Jonestown
(PFC mixture was placed in February 2004)
Averages % Change
Year 2001 2002 2003 2004 2001-2003 in 2004
Total # of accidents 29 51 44 17 41.3 -58.9
Dry weather accidents 10 23 13 15 15.3 -2.2
Wet weather accidents 19 28 21 2 22.7 -91.2
Fatalities 0 1 5 0 2.0 -100.0
Total injuries 25 16 21 0 20.7 -100.0
Incapacitating injuries* 6 4 3 0 4.3 -100.0
Non-incapacitating injuries 19 12 18 0 16.3 -100.0
Annual rainfall (inches) 42.9 36.0 21.4 52.0 33.4 55.5
Total rain days (>0.1 in.) 57 56 37 70 50.0 40.0
* Some of these injuries later became fatalities
Source: Cedar Park Police Department

25. Safety is a Major Quality of Life Issue

26. Conclusions
TxDOT uses a variety of 4 different HMA
mixtures
Goal: Select the most appropriate mixture type
for each given application
The use of PFC and SMA is increasing in
Texas due to the unique properties of these
mixes
PFC is considered to be the quietest and safest
option currently available for paving

27. Thank You
Texas
Department
of Transportation