overview of the fhwa pavement friction management … david de león izeppi.pdf · objectives (with...

Overview of the FHWA Pavement Friction Management Program

Virginia Polytechnic Institute and State UniversityCharles E. Via Jr. Department of Civil Engineering

Edgar de León Izeppi

Outline

Development and Demonstration of Pavement Friction Mgt. Programs:

(FHWA DTFH61-09-R-00035) Objectives Background Research Team Research Plan Phase I & II Approaches for friction threshold level

Center for Sustainable Transportation Infrastructure

Objectives (with four states)

Determine criteria and methods, for investigatory (desirable) level and intervention (minimum) levels for friction and macro-texture for different demand/classes of highways.

Assist in developing PFM Programs. Demonstrate state-of-the-art friction

(and macro-texture) measurement equipment.


FHWA T 5040.38

Background

Goal: Reduce crashes (& fatalities) Evaluate recommendations of the

2008 AASHTO Guide for Pavement Friction.

Major strategy is to determine investigatory/intervention threshold values, based on analysis of crash data & determine friction and/or macrotexture requirements



FHWA COTR

Gerardo Flintsch (VTTI)Principal Investigator

Kelly Smith (APTech)Research Team Leader

Edgar de Leon (VTTI)Equipment Team Leader

Gerardo FlintschPFM Program Team Leader

Todd Hoerner (APTech)Database Developer/ Data Analyst

Feng Guo (VTTI)Statistician/ Safety Analyst

Roger Larson (APTech)Technical Advisor

William Hobbs (VTTI)Equipment Operator

Kurt Smith (APTech)Technical Advisor/ Project QA/QC

James Krstulovich (APTech)Data Collector/Data Analyst

Alejandra Medina (VTTI)Safety Analyst

Kevin McGhee (VTRC)Implementation Leader

James Wambold (CDRM)Technical Advisor

Kelly Smith (APTech)Co-Principal Investigator

Helen Viner (TRL)Program Developer

Peter Roe (TRL)Program Developer

James Krstulovich (APTech)Equipment Operator (as needed)

Tony Parry (TRL/UoN)Technical Expert

Center for Sustainable Transportation InfrastructureSource: International Road Traffic and Accident Database (IRTAD)

Phase I Research Plan


Demonstrate state-of-the-art friction (and macro-texture) measurement equipment


Source: Delane (2005)

Friction measurement equipment


1 Effectiveness in the prediction of (fatal) crash potential 2 Continuous friction measurement capability and operating

principle 3 Macrotexture measurement 4 Stage of development of the device (experimental or

commercially available) 5 Robustness and readiness for deployment 6 Data collection productivity 7 Measurement speed 8 Precision (Repeatability and Reproducibility) 9 Global Positioning System (GPS) 10 Software

Evaluation Criteria1) Effectiveness predicting fatal crashes2) Continuous measurement principle

a) % Slip ratio (or equivalent)b) Type of tirec) Tire pressure (psi)d) Left-wheel path tiree) Right-wheel path tire possible

3) Macrotexture measurementa) Speed (kHz) b) Sampling distance

4) Commercially available5) Robustness and readiness for deploy

a) One operator capableb) Left side steering wheel availablec) Complete package from supplierd) Vertical load (lbs.)e) Dynamic vertical load sensor


Evaluation Criteria (cont.)6) Data collection productivity

a) Typical water tank capacity (gallons)b) Range per tank (miles)

7) Measurement speed (recommended)a) Minimum/Maximum (mph/mph)

8) Precisiona) Repeatabilityb) Reproducibilityc) Length for the mean value (feet)

9) GPS-capable10) Highway Software available11) Other

a) Highway track record (number of devices in use)b) Delivery time (months)c) Cost of the 2 year technical support and maintenance agreement


Phase II Research Plan


Different Approaches for setting investigatory (desirable) level and intervention (minimum)

levels for friction and macro-texture


AASHTO Guide Pavement Friction threshold method


Pavement Age, years

F(60

),Sp

or

FN Investigatory Level

Intervention Level

Friction

Pavement Age, years

F(60

),Sp

or


Intervention Level

Friction

Pavement Age, years

F(60

),Sp

or


Intervention Level Cra

sh R

ates

Friction

Crash Rates

Pavement Age, years

F(60

),Sp

or


Intervention Level Cra

sh R

ates

Friction

Crash Rates

F(60) ,Sp or FN

Num

ber o

f Site

s

Wet

to D

ry C

rash

es, %

InterventionLevel

InvestigatoryLevel

Wet to DryCrashes

Mean – X*(Std Dev)

Mean – Y*(Std Dev)

F(60) ,Sp or FN

Num

ber o

f Site

s

Wet

to D

ry C

rash

es, %

InterventionLevel

InvestigatoryLevel

Wet to DryCrashes

Mean – X*(Std Dev)

Mean – Y*(Std Dev)

Alternative Approaches E.g., Model the probability of wet crash

as a function of friction number using logistic regression


10 20 30 40 50 60 70 800

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16Estimated Probabilty of Accident with Confidence Interval

FN

Pred

icted

Pro

babil

ty


0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65

A Motorway

B Dual carriageway non-event

C Single carriageway non-event

Q Approaches to and across minor and major junctions, approaches to roundabouts

K Approaches to pedestrian crossings and other high risk situations

R Roundabout

G1 Gradient 5-10% longer than 50m

G2 Gradient >10% longer than 50m

S1 Bend radius < 500m - dual carriageway

S2 Bend radius < 500m - single carriageway

Investigatory level (50 or 80 km/h)Site category and definition

Investigatory Levels (UK-English)


0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65

A Interstate highways

B Divided highways w/o intersections, grade, etc.

C Two lane road w/o intersections, grade, etc.

Q Intersection (& roundabouts)

K Pedestrian crossings and other high risk areas

R Roundabout

G1 Slope 5-10%, longer than 160 feet

G2 Slope >10% longer than 160 feet

S1 Curve radius < 1600 feet - divided roads

S2 Curve radius < 1600 feet - two lane roads

Road classification definitionsInvestigatory level (31 or 50 mph)

Investigatory Levels (US-English)

edeleoni@vt. edu

Questions?

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