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Publication Number: FHWA-RD-03-092
Date: May 2006

Verification of LTPP Virtual Weather Stations Phase I Report: Accuracy and Reliability of Virtual Weather Stations

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FOREWORD

Within the Long-Term Pavement Performance (LTPP) program, two sources of data are used to characterize the climatic conditions for each test section. For the majority of the test sections, data for nearby national weather stations are obtained from the National Climatic Data Center (NCDC) and are used to compute estimated data for a virtual test section located at the test section. In addition, onsite instrumentation is used to obtain site-specific climatic data for the test sections included in the Seasonal Monitoring Program and for the Specific Pavement Studies (SPS)–1, –2, and –8 project sites.

This report documents a study undertaken to examine the reliability and accuracy of the LTPP climatic data. The study confirmed that accurate daily, monthly, and yearly estimates of climatic data for a project location can be derived by using the NCDC weather data for several nearby weather stations. The variation in the climatic data also was characterized.

Gary L. Henderson
Director, Office of Infrastructure Research and Development

 

NOTICE

This document is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The U.S. Government assumes no liability for its contents or use thereof. This report does not constitute a standard, specification, or regulation.

The U.S. Government does not endorse products or manufacturers. Trade or manufacturers’ names appear herein only because they are considered essential to the objective of this document.

QUALITY ASSURANCE STATEMENT

The Federal Highway Administration (FHWA) provides high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement.

 

Technical Report Documentation Page

1. Report No
FHWA-RD-03-092
2. Government Accession No.
N/A
3. Recipient's Catalog No.
N/A
4. Title and Subtitle
Verification of Long-Term Pavement Performance Virtual Weather Stations: Phase I Report—Accuracy and Reliability of Virtual Weather Stations
5. Report Date
May 2006
6. Performing Organization Code
N/A
7. Authors(s)
Alaeddin Mohseni, Ph.D., P.E.
8. Performing Organization Report No.
N/A
9. Performing Organization Name and Address
Alaeddin Mohseni, Ph.D., P.E.
6105 Maiden Lane
Bethesda, MD 20817
10. Work Unit No. (TRAIS)
N/A
11. Contract or Grant No.
DTFH61-95-Z-00086
13. Type of Report and Period Covered
Final Report
March 2001–January 2002
12. Sponsoring Agency Name and Address
Office of Research and Technology Services
Federal Highway Administration
6300 Georgetown Pike
McLean, VA 22101
14. Sponsoring Agency Code
15. Supplementary Notes
Contracting Officer’s Technical Representative (COTR): Monte Symons, HRDI-13
16. Abstract
Within the Long-Term Pavement Performance (LTPP) program, two sources of data are used to characterize the climatic conditions for each test section. For the majority of the test sections, data for nearby national weather stations are obtained from the National Climatic Data Center (NCDC) and are used to compute estimated data for a virtual test section located at the test section. In addition, onsite instrumentation is used to obtain site-specific climatic data for the test sections included in the Seasonal Monitoring Program and for the Specific Pavement Studies (SPS) –1, –2, and –8 project sites.

This report documents a study undertaken to examine the reliability and accuracy of the LTPP climatic data. The study confirmed that accurate daily, monthly, and yearly estimates of climatic data for a project location can be derived by using the NCDC weather data for several nearby weather stations. The variation in the climatic data was also characterized.
17. Key Words
Pavements, weather stations, LTPP, climatic data, temperature, precipitation.
18. Distribution Statement
No restrictions. This document is available to the public through the National Technical Information Service, Springfield, VA 22161.
19. Security Classif. (of this report)
Unclassified
20. Security Classif. (of this page)
Unclassified
21. No. of Pages
91
22. Price
N/A

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized (art. 5/94)

SI* (Modern Metric) Conversion Factors


TABLE OF CONTENTS

LIST OF FIGURES

  1. Diagram. Schema of VWS concept
  2. Equation. Estimating climatic data
  3. Graph. Estimated versus measured maximum temperature for section 331001
  4. Graph. Estimated versus measured maximum temperature for site 010100
  5. Graph. Estimated versus measured maximum temperature for site 040100
  6. Bar chart. Error distribution of maximum temperature estimates for AWS sites
  7. Bar chart. Error distribution of minimum temperature estimates for AWS sites
  8. Bar chart. Error distribution of maximum temperature estimates for SMP sites
  9. Bar Chart. Error distribution of minimum temperature estimates for SMP sites
  10. Graph. AWS versus SMP measured maximum temperature for site 010100
  11. Graph. AWS versus SMP measured maximum temperature for site 040100
  12. Graph. Temperature difference between site 460800 and nearby weather stations versus distance
  13. Graph. Mean maximum temperature difference versus distance for AWS and SMP sites
  14. Graph. Mean minimum temperature difference versus distance for AWS and SMP sites
  15. Graph. Standard deviation of maximum temperature difference versus distance for AWS and SMP sites
  16. Graph. Standard deviation of minimum temperature difference versus distance for AWS and SMP sites
  17. Graph. Mean maximum temperature difference versus distance for NCDC sites
  18. Graph. Mean minimum temperature difference versus distance for NCDC sites
  19. Graph. Standard deviation of maximum temperature difference versus distance for NCDC sites
  20. Graph. Standard deviation of minimum temperature difference versus distance for NCDC sites
  21. Graph. Average maximum temperature difference versus elevation difference for AWS and SMP sites
  22. Graph. Average minimum temperature difference versus elevation difference for AWS and SMP sites
  23. Graph. Standard deviation of maximum temperature difference versus elevation difference for AWS and SMP sites
  24. Graph. Standard deviation of minimum temperature difference versus elevation difference for AWS and SMP sites
  25. Graph. Mean maximum temperature difference versus elevation difference for NCDC sites
  26. Graph. Mean minimum temperature difference versus elevation difference for NCDC sites
  27. Graph. Mean maximum temperature difference versus north-south distance for AWS and SMP sites
  28. Graph. Mean minimum temperature difference versus north-south distance for AWS and SMP sites
  29. Graph. Standard deviation of maximum temperature difference versus north-south distance for AWS and SMP sites
  30. Graph. Standard deviation of minimum temperature difference versus north-south distance for AWS and SMP sites
  31. Equation. Average temperature calculation
  32. Bar chart. Percent contribution of closest weather stations to VWS using the 1/R2 rule
  33. Bar chart. Percent contribution of closest weather stations to VWS using the 1/R rule
  34. Bar chart. Distribution of mean error for maximum temperature (NCDC data)
  35. Bar chart. Distribution of mean error for minimum temperature (NCDC data)
  36. Bar chart. Distribution of standard deviation of error for maximum temperature (NCDC data)
  37. Bar chart. Distribution of standard deviation of error for minimum temperature (NCDC data)
  38. Graph. Maximum air temperature for SMP sections 010101 versus 010102
  39. Graph. Minimum air temperature for SMP sections 010101 versus 010102

LIST OF TABLES

  1. Climatic data elements included in owsdaily.txt data file
  2. List of SMP sections used in this study
  3. List of AWS sites used in the analysis
  4. Counts of available SMP climatic data in DataPave 2.0
  5. Counts of AWS collected data for selected climatic parameters
  6. List of selected VWS climatic parameters reviewed for data completeness
  7. Record count of selected parameters for 788 GPS sections
  8. GPS sections and SPS sites without VWS estimates
  9. Sections with VWS data but not in the Experiment_Section table
  10. Record count for selected parameters for 74 SPS sites
  11. Distribution of years of climatic data for GPS and SPS sections
  12. Distribution of data coverage for different climatic parameters
  13. Total record counts and number of contributing weather stations for AWS estimates
  14. Summary statistics for error of daily temperature estimates
  15. Summary statistics for error of monthly temperature estimates
  16. Summary statistics for error of monthly precipitation and FI estimates
  17. Summary statistics for error of yearly precipitation and FI estimates
  18. Summary statistics for error of daily maximum and minimum humidity estimates
  19. Summary statistics for error of monthly maximum and minimum humidity estimates
  20. Summary statistics for error of daily average and maximum windspeed estimates
  21. Summary statistics for error of monthly average and maximum windspeed estimates
  22. Summary statistics for error of various LTPP VWS estimates for AWS and SMP sites
  23. Summary statistics for daily differences between SMP and AWS data
  24. Summary statistics for monthly difference between SMP and AWS data
  25. Year-to-year variation of virtual weather data
  26. Mean and standard deviation of temperature difference between NCDC site and the five nearby weather stations
  27. Summary statistics for error of daily and monthly estimates of AWS and SMP maximum temperature using five different calculation methods
  28. Summary statistics for error of daily estimates of AWS maximum temperature using three different calculation methods
  29. Summary statistics for error of daily estimates of SMP maximum temperature using three different calculation methods
  30. Summary statistics for error of daily estimates of SMP minimum temperature using three different calculation methods
  31. Summary statistics of mean error for maximum and minimum temperatures versus weather station elevation
  32. Summary statistics of error for AWS sections (corrected for elevation)
  33. Summary statistics of error for SMP sections (corrected for elevation)
  34. Overall mean and standard deviation of error of daily, monthly, and yearly estimates for NCDC sites
  35. VWS, AWS, and OWS maximum temperatures for AWS site 200100
  36. Sections with anomalies in daily SMP time data
  37. Sections with anomalies in daily SMP temperature change data
  38. Sections with anomalies in daily SMP temperature data
  39. Temperature data for two SMP installations within the same site

List of Acronyms and Abbreviations

AASHTO American Association of State Highway and Transportation Officials
AC asphalt concrete
ACI American Concrete Institute
ASTM American Society for Testing and Materials
CN construction numbers
CPR concrete pavement restoration
CRCP continuously reinforced concrete pavement
ESAL equivalent single axle load
FHWA Federal Highway Administration
FWD falling weight deflectometer
GPS General Pavement Studies
HMAC Hot-mix asphalt concrete
IMS Information Management System
JCP jointed concrete pavement
JPCP jointed plain concrete pavement
JRCP jointed reinforced concrete pavement
LTE load transfer efficiency
LTPP Long-Term Pavement Performance
PCC portland cement concrete
RSC Regional Support Contractor
SAMI stress-absorbing membrane interlayers
SHA State highway agency
SHRP Strategic Highway Research Program
SMP Seasonal Monitoring Program
SPS Specific Pavement Studies
TSSC Technical Support Services Contractor
VMA voids in mineral aggregate

FHWA-RD-03-092

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The Federal Highway Administration (FHWA) is a part of the U.S. Department of Transportation and is headquartered in Washington, D.C., with field offices across the United States. is a major agency of the U.S. Department of Transportation (DOT).
The Federal Highway Administration (FHWA) is a part of the U.S. Department of Transportation and is headquartered in Washington, D.C., with field offices across the United States. is a major agency of the U.S. Department of Transportation (DOT). Provide leadership and technology for the delivery of long life pavements that meet our customers needs and are safe, cost effective, and can be effectively maintained. Federal Highway Administration's (FHWA) R&T Web site portal, which provides access to or information about the Agency’s R&T program, projects, partnerships, publications, and results.
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