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Influence of Seasonal Temperature on Pavement Reliability Performance: A Case Study

Influence of Seasonal Temperature on Pavement Reliability Performance: A Case Study. Roya Amjadi Federal Highway Administration, Turner-Fairbank Highway Research Center (FHWA, TFHRC), United States of America Jim Sherwood

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Influence of Seasonal Temperature on Pavement Reliability Performance: A Case Study

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  1. Influence of Seasonal Temperature on Pavement Reliability Performance: A Case Study Roya Amjadi Federal Highway Administration, Turner-Fairbank Highway Research Center (FHWA, TFHRC), United States of America Jim Sherwood Federal Highway Administration, Turner-Fairbank Highway Research Center (FHWA, TFHRC), United States of America Gerardo Flintsch Virginia Tech, United States of America The 3rd International Road Surface Friction, Australia, May 15-18, 2011

  2. OBJECTIVE This exploratory study analyzed crash and pavement data to examine pavement reliability performance (PRP) for seasonal temperature changes in a U.S. State. PRP was examined for three pavement types: • pave1– asphalt overlay on flexible pavement • pave2 – asphalt overlay on rigid pavement • pave3 – Portland cement concrete.

  3. INTRODUCTION Anyone who has walked barefoot across a parking lot on a hot summer day knows that asphalt concrete (AC) or “blacktop” is exceptionally good at absorbing the sun's warmth. AC surface friction increases in early spring and decreases in early fall. The variation of skid number between early spring and early fall depends on the type of pavement, pavement design, materials, and geographical location.

  4. INTRODUCTION (cont.) A 1993,FHWA study produced Climatic-Materials-Structural (CMS) model that determines the changes in asphalt stiffness, resilient modulus, and poison’s ratio of the base, subbase, and subgrade with time. Material properties, pavement geometry, and other required data for input were provided by CMS Model. This study developed a model to study the temperature profile on asphalt pavements. However, there is no model to study the influence of temperature and type of surface on tire-surface friction.

  5. TECHNICAL RESOURCES NCHRP Report 500 Guidance for Implementation of the AASHTO Strategic Highway Safety Plan: • Volume 6: A Guide for Addressing Run-off-Road Collision, and • Volume 7: A Guide for Reducing Collision on Horizontal Curves Were used as guidance to isolate crash variables in warm and cold seasons for analysis from data files.

  6. METHODOLOGY Pave1 through pave3were compared for crash trends and how the seasons influence their PRP for: • SVROR/Fail to Control Vehicle? • Multivehicle crashes on Road (MVOR) versus SVROR? • SVROR/Overturn? • SVROR/Curve? • SVROR/Exceeding Speed Limit? • SVROR/Alcohol? • SVROR/Killed? • Does PRP vary according to pavement type and its AADT for each season?

  7. METHODOLOGY (cont.) • NCHRP Report 500, Volume 6: “ROR crashes involve vehicles that leave the travel lane and encroach onto shoulder and beyond and hit one or more on any number of natural or artificial objects such as bridge wall, poles, embankments, guardrails, parked vehicles, and trees.” • The proportions of SVROR are typically much lower than MVOR crashes on “safe” roadways. • A roadway or system is considered to have higher risk factors for SVROR when its SVROR crash proportion gets closer to, or greater than its MVROR crash proportion.

  8. METHODOLOGY Pavement sections have characteristics, such as Federal HWY Classification, number of lanes, lane and shoulder widths, pavement thicknesses, ages, conditions, AADTs, pavement designs, geometric designs, etc. For comparing pavement types in this type of analysis, crash data needs to be adjusted for all (or most of) the above variables.

  9. METHODOLOGY NCHRP Report 500, V6, states that overturn crashes are more likely for SVROR → Providing skid- resistant surfaces may help reduce SVROR NCHRP Report 500, V7, identifies that: • Providing skid-resistance pavement surfaces as a possible effective countermeasure for reducing likelihood of SVROR crashes. • Overturn is often an adverse consequence of SVROR on curves. • Fixed objects on roadside create hazardous roadway conditions on curves.

  10. METHODOLOGY (cont.) • Finding a statistical methodology that adjust each pavement type crash data for all involved variables is difficult and may not yield a reliable result. • Odds Ratio (OR) is an effective and efficient method that can be used to compare three pavement types’ PRP performance for areas of concern. • Proper samples were isolated for each pavement type, and they were analyzed independently, and pave1 OR was compared to the other ORs to determine which pavement has a higher effect compared to pave1.

  11. STATE Y AVERAGE MONTHLY TEMPERATURE (°F)

  12. Data Preparation

  13. Data Preparation (CONT.)

  14. Odds ratio for Various crash variables in warm vs. cold season

  15. RESULTS Effect of season on pave1: • SVROR/Fail to Control Vehicle OR corresponding to seasonal variations is 53 % higher thank for pave2, and 74 % higher than for pave3. • SVROR versus MVOR OR had a 19 % increase compared to pave2, and had a 27 % increase compared to pave3. • SVROR/Overturn OR had; a 17 % increase compared to pave2, and had a 36 % increase compared to pave3. • SVROR/Curve OR had a 100 % increase compared to pave2, and had a 72 % increase compared to pave3.

  16. RESULTS (CONT.) Effect of season on pave1: • SVROR/ Exceeding Speed Limit OR had a 29 % increase compared to pave2, and had a 30 % decrease compared to pave3. • SVROR/ Alcohol OR had a 33 % increase compared to pave2, and had a 15 % decrease compared to pave3. • SVROR/Killed OR had an 8 % decrease compared to pave2, and had a 41 % increase compared to pave3. • had a significantly higher (p-value = 0.04) SVROR crashes for Log10 (AADT)=<7,900 veh/day.

  17. SUMMARY & CONCLUSION • Average 44°F temperature difference between warm and cold seasons may increase percentage of crash odds ratio for certain variables in warm seasons. Due to the scope of this study, we could not determine all contributing factors behind this increase. • Comparing Warm Season to Cold Season for pave1 • Overall SVROR OR increased, • SVROR crash trends for driver contribution/fail to control vehicle increased, • crash type/overturn, and • road horizontal characteristic/curve were increased. • These increases ranged from from 17 % up to 100 % compared to pave2 and pave3.

  18. SUMMARY & CONCLUSION (CONT.) • In warm season pave1 OR for SVROR/exceeding speed limit, and alcohol related crashes are not increased compared to pave3. Pave1 SVROR/killed OR increased 41 % compared to pave3 for warm seasons. • Pave1 histograms for crash rate vs. Log10 (AADT) showed clear differences in the warm and cold weather crash rate distributions for categories of Log10 (AADT). • pave1 had a significantly higher (p-value = 0.04) SVROR crashes for Log10 (AADT)=<7,900 veh/day.

  19. RECOMMENDATIONS • The findings of this study are not intended to represent the final ruling on the relationship between seasonal changes and the reliability of these pavement types. • In future studies, pave1 PRP requires a closer examination for major contributing factors beside warm season temperature influence. • Further research in areas of pavement heat transfer, and how temperature affects viscoelastic material properties for rubber tire and hot-mix asphalt to reduce ROR crashes. • To use crash data for PRP and pavement design in order to open new doors for future pavement research, technology, and resources that result in lives saved.

  20. Norfolk, VA, September, 19-21, 2012 7th Symposium on Pavement Surface Characteristics SURF 2012 Smooth, Safe, Quiet, and Sustainable Travel through Innovative Technologies Deadline for submission of abstracts: July 31, 2011 www.SURF2012.org

  21. THANK YOU Question? Roya Amjadi, FHWA,TFHRC, USA Roya.amjadi@dot.gov Jim Sherwood, FHWA,TFHRC, USA Jim.sherwood@dot.gov Gerardo Flintsch, Virginia Tech, USA flintsch@vt.edu

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